Subsections


11. The LINUX unit.

linuxex This chapter describes the LINUX unit for Free Pascal. The unit was written by Michaël van Canneyt. It works only on the Linux operating system. This chapter is divided in 3 sections:

11.1 Type, Variable and Constant declarations


11.1.1 Types

PGlob and TGlob are 2 types used in the Glob function:
PGlob = ^TGlob;
TGlob = record
  Name : PChar;
  Next : PGlob;
  end;
The following types are used in the signal-processing procedures.
tfpreg = record
  significand: array[0..3] of word;
  exponent: word;
end;

pfpstate = ^tfpstate;
tfpstate = record
  cw, sw, tag, ipoff, cssel, dataoff, datasel: cardinal;
  st: array[0..7] of tfpreg;                            
  status: cardinal;
end;

PSigContextRec = ^SigContextRec;
SigContextRec = record
  gs, __gsh: word;
  fs, __fsh: word;
  es, __esh: word;
  ds, __dsh: word;
  edi: cardinal;   
  esi: cardinal;   
  ebp: cardinal;   
  esp: cardinal;   
  ebx: cardinal;   
  edx: cardinal;   
  ecx: cardinal;   
  eax: cardinal;   
  trapno: cardinal;
  err: cardinal;   
  eip: cardinal;   
  cs, __csh: word; 
  eflags: cardinal;
  esp_at_signal: cardinal;
  ss, __ssh: word;
  fpstate: pfpstate;
  oldmask: cardinal;
  cr2: cardinal;
  end;
The above records contain information about the processor state and process state at the moment a signal is sent to your program.

The records below are used in catching signals.

TSigAction = procedure(Sig: Longint; SigContext: SigContextRec);cdecl;
SignalHandler   = Procedure ( Sig : Integer);cdecl;

PSignalHandler  = SignalHandler;
SignalRestorer  = Procedure;cdecl;
PSignalrestorer = SignalRestorer;
SigActionRec = packed record
  Handler  : record
    case byte of   
      0: (Sh: SignalHandler);
      1: (Sa: TSigAction);   
    end;
  Sa_Mask     : SigSet;
  Sa_Flags    : Longint;
  Sa_restorer : SignalRestorer; { Obsolete - Don't use }
end;
  PSigActionRec = ^SigActionRec;
Stat is used to store information about a file. It is defined in the syscalls unit.
  stat = record
     dev    : word;
     pad1   : word;
     ino    : longint;
     mode   : word;
     nlink  : word;
     uid    : word;
     gid    : word;
     rdev   : word;
     pad2   : word;
     size   : longint;
     blksze : Longint;
     blocks : Longint;
     atime  : Longint;
     unused1 : longint;
     mtime   : Longint;
     unused2 : longint;
     ctime   : Longint;
     unused3 : longint;
     unused4 : longint;
     unused5 : longint;
     end;
Statfs is used to store information about a filesystem. It is defined in the syscalls unit.
   statfs = record
     fstype   : longint;
     bsize    : longint;
     blocks   : longint;
     bfree    : longint;
     bavail   : longint;
     files    : longint;
     ffree    : longint;
     fsid     : longint;
     namelen  : longint; 
     spare    : array [0..6] of longint;
     end
Dir and PDir are used in the OpenDir and ReadDir functions.
  TDir =record
    fd     : integer;
    loc    : longint;
    size   : integer;
    buf    : pdirent;
    nextoff: longint;
    dd_max : integer; 
    lock   : pointer;
  end;
  PDir =^TDir;
Dirent, PDirent are used in the ReadDir function to return files in a directory.
 PDirent = ^Dirent;
 Dirent = Record  
   ino,
   off    : longint;
   reclen : word;
   name   : string[255]
 end;
Termio and Termios are used with iotcl() calls for terminal handling.
Const  NCCS = 19;
       NCC = 8;
         
Type termio = record
	c_iflag,		{ input mode flags }
	c_oflag,		{ output mode flags }
	c_cflag,		{ control mode flags }
	c_lflag : Word;		{ local mode flags }
	c_line : Word;		{ line discipline - careful, only High byte in use}
	c_cc : array [0..NCC-1] of char;	{ control characters }
end;
termios = record
  c_iflag,              { input mode flags }
  c_oflag,              { output mode flags }
  c_cflag,              { control mode flags }
  c_lflag : Cardinal;	{ local mode flags }
  c_line : char;          { line discipline }
  c_cc : array [0..NCCS-1] of char;      { control characters }
end;
Utimbuf is used in the Utime call to set access and modificaton time of a file.
utimbuf = record
  actime,modtime : Longint;
  end;
For the Select call, the following 4 types are needed:
FDSet = Array [0..31] of longint;
PFDSet = ^FDSet;
TimeVal = Record
   sec,usec : Longint;
end;
PTimeVal = ^TimeVal;
The Uname function uses the utsname to return information about the current kernel :
utsname =record
  sysname,nodename,release,
  version,machine,domainname : Array[0..64] of char;
end;
Its elements are null-terminated C style strings, you cannot access them directly !

11.1.2 Variables

Linuxerror is the variable in which the procedures in the linux unit report errors.
LinuxError : Longint;
StdErr Is a Text variable, corresponding to Standard Error or diagnostic output. It is connected to file descriptor 2. It can be freely used, and will be closed on exit.
StdErr : Text;

11.1.3 Constants

Constants for setting/getting process priorities :
      Prio_Process = 0;
      Prio_PGrp    = 1;
      Prio_User    = 2;
For testing access rights:
      R_OK = 4; 
      W_OK = 2;
      X_OK = 1;
      F_OK = 0;
For signal handling functions :
      SA_NOCLDSTOP = 1;
      SA_SHIRQ	   = $04000000;
      SA_STACK	   = $08000000;      
      SA_RESTART   = $10000000;
      SA_INTERRUPT = $20000000;
      SA_NOMASK	   = $40000000;
      SA_ONESHOT   = $80000000;
      
      SIG_BLOCK	  = 0;
      SIG_UNBLOCK = 1;
      SIG_SETMASK = 2;
      SIG_DFL = 0 ;
      SIG_IGN = 1 ;
      SIG_ERR = -1;
      
      SIGHUP		= 1;
      SIGINT		= 2;
      SIGQUIT		= 3;
      SIGILL		= 4;
      SIGTRAP		= 5;
      SIGABRT		= 6;
      SIGIOT		= 6;
      SIGBUS		= 7;
      SIGFPE		= 8;
      SIGKILL		= 9;
      SIGUSR1		= 10;
      SIGSEGV		= 11;
      SIGUSR2		= 12;
      SIGPIPE		= 13;
      SIGALRM		= 14;
      SIGTERM		= 15;
      SIGSTKFLT		= 16;
      SIGCHLD		= 17;
      SIGCONT		= 18;
      SIGSTOP		= 19;
      SIGTSTP		= 20;
      SIGTTIN		= 21;
      SIGTTOU		= 22;
      SIGURG		= 23;
      SIGXCPU		= 24;
      SIGXFSZ		= 25;
      SIGVTALRM		= 26;
      SIGPROF		= 27;
      SIGWINCH		= 28;
      SIGIO		= 29;
      SIGPOLL		= SIGIO;
      SIGPWR		= 30;
      SIGUNUSED		= 31;
For file control mechanism :
      F_GetFd  = 1;
      F_SetFd  = 2;
      F_GetFl  = 3;
      F_SetFl  = 4;
      F_GetLk  = 5;
      F_SetLk  = 6;
      F_SetLkW = 7;
      F_GetOwn = 8;
      F_SetOwn = 9;
For Terminal handling :
   TCGETS	= $5401 ;
   TCSETS	= $5402 ;
   TCSETSW	= $5403 ;
   TCSETSF	= $5404 ;
   TCGETA	= $5405 ;
   TCSETA	= $5406 ;
   TCSETAW	= $5407 ;
   TCSETAF	= $5408 ;
   TCSBRK	= $5409 ;
   TCXONC	= $540A ;
   TCFLSH	= $540B ;
   TIOCEXCL	= $540C ;
   TIOCNXCL	= $540D ;
   TIOCSCTTY	= $540E ;
   TIOCGPGRP	= $540F ;
   TIOCSPGRP	= $5410 ;
   TIOCOUTQ	= $5411 ;
   TIOCSTI	= $5412 ;
   TIOCGWINSZ	= $5413 ;
   TIOCSWINSZ	= $5414 ;
   TIOCMGET	= $5415 ;
   TIOCMBIS	= $5416 ;
   TIOCMBIC	= $5417 ;
   TIOCMSET	= $5418 ;
   TIOCGSOFTCAR	= $5419 ;
   TIOCSSOFTCAR	= $541A ;
   FIONREAD	= $541B ;
   TIOCINQ	= FIONREAD;
   TIOCLINUX	= $541C ;
   TIOCCONS	= $541D ;
   TIOCGSERIAL	= $541E ;
   TIOCSSERIAL	= $541F ;
   TIOCPKT	= $5420 ;
   FIONBIO	= $5421 ;
   TIOCNOTTY	= $5422 ;
   TIOCSETD	= $5423 ;
   TIOCGETD	= $5424 ;
   TCSBRKP		= $5425	 ;
   TIOCTTYGSTRUCT	= $5426  ;
   FIONCLEX	= $5450  ;
   FIOCLEX		= $5451 ;
   FIOASYNC	= $5452 ;
   TIOCSERCONFIG	= $5453 ;
   TIOCSERGWILD	= $5454 ;
   TIOCSERSWILD	= $5455 ;
   TIOCGLCKTRMIOS	= $5456 ;
   TIOCSLCKTRMIOS	= $5457 ;
   TIOCSERGSTRUCT	= $5458  ;
   TIOCSERGETLSR   = $5459  ;
   TIOCSERGETMULTI = $545A  ;
   TIOCSERSETMULTI = $545B  ;
   TIOCMIWAIT	= $545C	;
   TIOCGICOUNT	= $545D	;
   TIOCPKT_DATA		= 0;
   TIOCPKT_FLUSHREAD	= 1;
   TIOCPKT_FLUSHWRITE	= 2;
   TIOCPKT_STOP		= 4;
   TIOCPKT_START	= 8;
   TIOCPKT_NOSTOP	= 16;
   TIOCPKT_DOSTOP	= 32;
Other than that, all constants for setting the speed and control flags of a terminal line, as described in the termios (2) man page, are defined in the linux unit. It would take too much place to list them here. To check the mode field of a stat record, you ca use the following constants :
  { Constants to check stat.mode }
  STAT_IFMT   = $f000; {00170000}
  STAT_IFSOCK = $c000; {0140000}
  STAT_IFLNK  = $a000; {0120000}
  STAT_IFREG  = $8000; {0100000}
  STAT_IFBLK  = $6000; {0060000}
  STAT_IFDIR  = $4000; {0040000}
  STAT_IFCHR  = $2000; {0020000}
  STAT_IFIFO  = $1000; {0010000}
  STAT_ISUID  = $0800; {0004000}
  STAT_ISGID  = $0400; {0002000}
  STAT_ISVTX  = $0200; {0001000}
  { Constants to check permissions }
  STAT_IRWXO = $7;
  STAT_IROTH = $4;
  STAT_IWOTH = $2;
  STAT_IXOTH = $1;
  STAT_IRWXG = STAT_IRWXO shl 3;
  STAT_IRGRP = STAT_IROTH shl 3;
  STAT_IWGRP = STAT_IWOTH shl 3;
  STAT_IXGRP = STAT_IXOTH shl 3;
  STAT_IRWXU = STAT_IRWXO shl 6;
  STAT_IRUSR = STAT_IROTH shl 6;
  STAT_IWUSR = STAT_IWOTH shl 6;
  STAT_IXUSR = STAT_IXOTH shl 6;
You can test the type of a filesystem returned by a FSStat call with the following constants:
  fs_old_ext2 = $ef51;
  fs_ext2     = $ef53;
  fs_ext      = $137d;
  fs_iso      = $9660;
  fs_minix    = $137f;
  fs_minix_30 = $138f;
  fs_minux_V2 = $2468;
  fs_msdos    = $4d44;
  fs_nfs      = $6969;
  fs_proc     = $9fa0;
  fs_xia      = $012FD16D;
the FLock call uses the following mode constants :
  LOCK_SH = 1;
  LOCK_EX = 2;
  LOCK_UN = 8;
  LOCK_NB = 4;
The MMap function uses the following constants to specify access to mapped memory:
  PROT_READ  = $1;   { page can be read }
  PROT_WRITE = $2;   { page can be written } 
  PROT_EXEC  = $4;   { page can be executed }
  PROT_NONE  = $0;   { page can not be accessed }
and the following constants to specify the type of mapping.
  MAP_SHARED    = $1;  { Share changes }
  MAP_PRIVATE   = $2;  { Changes are private }
  MAP_TYPE      = $f;  { Mask for type of mapping }
  MAP_FIXED     = $10; { Interpret addr exactly }
  MAP_ANONYMOUS = $20; { don't use a file }

11.2 Function list by category

What follows is a listing of the available functions, grouped by category. For each function there is a reference to the page where you can find the function.

11.2.1 File Input/Output routines

Functions for handling file input/output. Dup Duplicate a file handle]
Dup2 Copy one file handle to another
Fcntl General file control
fdClose Close file descriptor
fdFlush Flush file descriptor
fdOpen Open new file descriptor
fdRead Read from file descriptor
fdSeek Position in file
fdTruncate Truncate file
fdWrite Write to file descriptor
GetFS Get file descriptor of pascal file
Select Wait for input from file descriptor
SelectText Wait for input from pascal file

11.2.2 General File handling routines

Functions for handling files on disk. Access Check access rights on file]
BaseName Return name part of file
Chown Change owner of file
Chmod Change access rights on file
DirName Return directory part of file
LFsplit Split filename in parts
FExpand Return full-grown filename
FLock Set lock on a file
FNMatch Match filename to searchpattern
FSearch Search for a file in a path
FSStat Return filesystem information
FStat Return file information
FRename Rename file
LStat Return information on a link
Link Create a link
ReadLink Read contents of a symbolic link
SymLink Create a symbolic link
Umask Set the file creation mask
UnLink Remove a file
Utime Change file timestamps

11.2.3 Pipes, FIFOs and streams

Functions for creating and managing pipes. AssignPipe Create a pipe]
AssignStream Create pipes to program's input and output
MkFifo Make a fifo
PClose Close a pipe
POpen Open a pipe for to program's input or output

11.2.4 Directory handling routines

Functions for reading and searching directories. CloseDir Close directory handle]
Glob Return files matching a search expression
GlobFree Free result of Glob
OpenDir Open directory for reading
ReadDir Read directory entry
SeekDir Seek directory
TellDir Seek directory

11.2.5 Process handling

Functions for managing processes and programs. Clone Create a thread]
Execl Execute process with command-line list
Execle Execute process with command-line list and environment
Execlp Search in path and execute process with command list
Execv Execute process
Execve Execute process with environment
Execvp Search in path and execute process
Fork Spawn child process
GetEGid Get effective group id
GetEnv Get environment variable
GetEUid Get effective user id
GetGid Get group id
GetPid Get process id
GetPPid Get parent process id
GetPriority Get process priority
GetUid Get user id
Nice Change priority of process
SetPriority Change priority of process
Shell Execute shell command
WaitPid Wait for child process to terminate

11.2.6 Signals

Functions for managing and responding to signals. Alarm Send alarm signal to self]
Kill Send arbitrary signal to process
pause Wait for signal to arrive
SigAction Set signal action
Signal Set signal action
SigPending See if signals are waiting
SigProcMask Set signal processing mask
SigRaise Send signal to self
SigSuspend Sets signal mask and waits for signal

11.2.7 System information

Functions for retrieving system information such as date and time. GetDate Return system date]
GetDateTime Return system date and time
GetDomainName Return system domain name
GetEpochTime Return epoch time
GetHostName Return system host name
GetLocalTimezone Return system timezone
GetTime Return system time
GetTimeOfDay Return system time
GetTimezoneFile Return name of timezone file
ReadTimezoneFile Read timezone file contents
SysInfo Return general system information
Uname Return system information

11.2.8 Terminal functions

Functions for controlling the terminal to which the process is connected.

CFMakeRaw Set terminal to raw mode]

CFSetISpeed Set terminal reading speed
CFSetOSpeed Set terminal writing speed
IOCtl General IO control call
IsATTY See if filedescriptor is a terminal
TCDrain Wait till all output was written
TCFlow Suspend transmission or receipt of data
TCFlush Discard data written to terminal
TCGetAttr Get terminal attributes
TCGetPGrp Return PID of foreground process
TCSendBreak Send data for specific time
TCSetAttr Set terminal attributes
TCSetPGrp Set foreground process
TTYName Name of tty file

11.2.9 Port input/output

Functions for reading and writing to the hardware ports. IOperm Set permissions for port access]
ReadPort Read data from port
ReadPortB Read 1 byte from port
ReadPortL Read 4 bytes from port
ReadPortW Read 2 bytes from port
WritePort Write data to port
WritePortB Write 1 byte to port
WritePortL Write 4 bytes to port
WritePortW Write 2 bytes to port

11.2.10 Utility routines

Auxiliary functions that are useful in connection with the other functions. CreateShellArgV Create an array of pchars from string]
EpochToLocal Convert epoch time to local time
FDClr Clear item of select filedescriptors
FDIsSet Check item of select filedescriptors
FDSet Set item of select filedescriptors
FDZero Clear all items in select filedecriptors
LocalToEpoch Convert local time to epoch time
MMap Map a file into memory
MUnMap Unmap previously mapped memory file
Octal Convert octal to digital
ISBLK Check file mode for block device
ISCHR Check file mode for character device
ISDIR Check file mode for directory
ISFIFO Check file mode for FIFO
ISLNK Check file mode for symboloc link
ISREG Check file mode for regular file
ISSOCK Check file mode for socket
StringToPPchar Create an array of pchars from string

11.3 Functions and procedures


11.3.1 Access

Declaration
Function Access (Path : Pathstr; Mode : integer) : Boolean;
Description
Tests user's access rights on the specified file. Mode is a mask existing of one or more of
R_OK
User has read rights.
W_OK
User has write rights.
X_OK
User has execute rights.
F_OK
User has search rights in the directory where the file is.
The test is done with the real user ID, instead of the effective user ID. If access is denied, or an error occurred, false is returned.
Errors
LinuxError is used to report errors:
sys_eaccess
The requested access is denied, either to the file or one of the directories in its path.
sys_einval
Mode was incorrect.
sys_enoent
A directory component in Path doesn't exist or is a dangling symbolic link.
sys_enotdir
A directory component in Path is not a directory.
sys_enomem
Insufficient kernel memory.
sys_eloop
Path has a circular symbolic link.

See also
Chown, Chmod, Access (2)

Example
Program Example26;

{ Program to demonstrate the Access function. }

Uses linux;

begin
  if Access ('/etc/passwd',W_OK) then
    begin
    Writeln ('Better check your system.');
    Writeln ('I can write to the /etc/passwd file !');
    end;
end.


11.3.2 Alarm

Declaration
Function Alarm(Sec : longint) : Longint;
Description
Alarm schedules an alarm signal to be delivered to your process in Sec seconds. When Sec seconds have elapsed, Linux will send a SIGALRM signal to the current process. If Sec is zero, then no new alarm will be set. Whatever the value of Sec, any previous alarm is cancelled.

The function returns the number of seconds till the previously scheduled alarm was due to be delivered, or zero if there was none.

Errors
None

Example
Program Example59;

{ Program to demonstrate the Alarm function. }

Uses linux;

Procedure AlarmHandler(Sig : longint);cdecl;

begin
  Writeln ('Got to alarm handler');
end;

begin
  Writeln('Setting alarm handler');
  Signal(SIGALRM,@AlarmHandler);
  Writeln ('Scheduling Alarm in 10 seconds');
  Alarm(10);
  Writeln ('Pausing');
  Pause;
  Writeln ('Pause returned');
end.


11.3.3 AssignPipe

Declaration
Function AssignPipe(var pipe_in,pipe_out:longint):boolean; Function AssignPipe(var pipe_in,pipe_out:text):boolean; Function AssignPipe(var pipe_in,pipe_out:file):boolean;
Description
AssignePipe creates a pipe, i.e. two file objects, one for input, one for output. What is written to Pipe_out, can be read from Pipe_in.

This call is overloaded. The in and out pipe can take three forms: an typed or untyped file, a text file or a file descriptor.

If a text file is passed then reading and writing from/to the pipe can be done through the usual Readln(Pipe_in,...) and Writeln (Pipe_out,...) procedures.

The function returns True if everything went succesfully, False otherwise.

Errors
In case the function fails and returns False, LinuxError is used to report errors:
sys_emfile
Too many file descriptors for this process.
sys_enfile
The system file table is full.
See also
POpen, MkFifo, pipe (2)

Example
Program Example36;

{ Program to demonstrate the AssignPipe function. }

Uses linux;

Var pipi,pipo : Text;
    s : String;
    
begin
  Writeln ('Assigning Pipes.');
  If Not assignpipe(pipi,pipo) then
    Writeln('Error assigning pipes !',LinuxError);
  Writeln ('Writing to pipe, and flushing.');
  Writeln (pipo,'This is a textstring');close(pipo);
  Writeln ('Reading from pipe.');
  While not eof(pipi) do 
    begin
    Readln (pipi,s);
    Writeln ('Read from pipe : ',s);
    end;
  close (pipi);
  writeln ('Closed pipes.');
  writeln
end.


11.3.4 AssignStream

Declaration
Function AssignStream(Var StreamIn,Streamout:text; Const Prog:String) : longint; Function AssignStream(var StreamIn, StreamOut, StreamErr: Text; const prog: String): LongInt;
Description
AssignStream creates a 2 or 3 pipes, i.e. two (or three) file objects, one for input, one for output,(and one for standard error) the other ends of these pipes are connected to standard input and output (and standard error) of Prog. Prog is the name of a program (including path) with options, which will be executed.

What is written to StreamOut, will go to the standard input of Prog. Whatever is written by Prog to it's standard output can be read from StreamIn. Whatever is written by Prog to it's standard error read from StreamErr, if present.

Reading and writing happens through the usual Readln(StreamIn,...) and Writeln (StreamOut,...) procedures.

Remark: You should not use Reset or Rewrite on a file opened with POpen. This will close the file before re-opening it again, thereby closing the connection with the program.

The function returns the process ID of the spawned process, or -1 in case of error.

Errors
In case of error (return value -1) LinuxError is used to report errors:
sys_emfile
Too many file descriptors for this process.
sys_enfile
The system file table is full.
Other errors include the ones by the fork and exec programs
See also
AssignPipe, POpen,pipe (2)

Example
Program Example38;

{ Program to demonstrate the AssignStream function. }

Uses linux;

Var Si,So : Text;
    S : String;
    i : longint;
        
begin
  if not (paramstr(1)='-son') then
    begin
    Writeln ('Calling son');
    Assignstream (Si,So,'./ex38 -son');
    if linuxerror<>0 then 
      begin
      writeln ('AssignStream failed !');
      halt(1);
      end;
    Writeln ('Speaking to son');
    For i:=1 to 10 do 
      begin
      writeln (so,'Hello son !');
      if ioresult<>0 then writeln ('Can''t speak to son...');
      end;
    For i:=1 to 3 do writeln (so,'Hello chap !');
    close (so);
    while not eof(si) do
      begin
      readln (si,s);
      writeln ('Father: Son said : ',S);
      end;
    Writeln ('Stopped conversation');
    Close (Si);
    Writeln ('Put down phone');
    end
  Else
    begin
    Writeln ('This is the son ');
    While not eof (input) do 
      begin
      readln (s);
      if pos ('Hello son !',S)<>0 then
         Writeln ('Hello Dad !')
      else 
         writeln ('Who are you ?');
      end;
    close (output);
    end 
end.


11.3.5 BaseName

Declaration
Function BaseName (Const Path;Const Suf : Pathstr) : Pathstr;
Description
Returns the filename part of Path, stripping off Suf if it exists. The filename part is the whole name if Path contains no slash, or the part of Path after the last slash. The last character of the result is not a slash, unless the directory is the root directory.

Errors
None.
See also
DirName, FExpand, Basename (1)

Example
Program Example48;

{ Program to demonstrate the BaseName function. }

Uses linux;

Var S : String;

begin
  S:=FExpand(Paramstr(0));
  Writeln ('This program is called : ',Basename(S,''));
end.


11.3.6 CFMakeRaw

Declaration
Procedure CFMakeRaw (var Tios:TermIOS);
Description
CFMakeRaw Sets the flags in the Termios structure Tios to a state so that the terminal will function in Raw Mode.

Errors
None.
See also
CFSetOSpeed, CFSetISpeed, termios (2)
For an example, see TCGetAttr.


11.3.7 CFSetISpeed

Declaration
Procedure CFSetISpeed (var Tios:TermIOS;Speed:Longint);
Description
CFSetISpeed Sets the input baudrate in the TermIOS structure Tios to Speed.

Errors
None.
See also
CFSetOSpeed, CFMakeRaw, termios (2)


11.3.8 CFSetOSpeed

Declaration
Procedure CFSetOSpeed (var Tios:TermIOS;Speed:Longint);
Description
CFSetOSpeed Sets the output baudrate in the Termios structure Tios to Speed.

Errors
None.
See also
CFSetISpeed, CFMakeRaw, termios (2)


11.3.9 Chown

Declaration
Function Chown (Path : Pathstr;NewUid,NewGid : Longint) : Boolean;
Description
Chown sets the User ID and Group ID of the file in Path to NewUid, NewGid. The function returns True if the call was succesfull, False if the call failed.
Errors
Errors are returned in LinuxError.
sys_eperm
The effective UID doesn't match the ownership of the file, and is not zero. Owner or group were not specified correctly.
sys_eaccess
One of the directories in Path has no search (=execute) permission.
sys_enoent
A directory entry in Path does not exist or is a symbolic link pointing to a non-existent directory.
sys_enotdir
A directory entry in OldPath or NewPath is nor a directory.
sys_enomem
Insufficient kernel memory.
sys_erofs
The file is on a read-only filesystem.
sys_eloop
Path has a reference to a circular symbolic link, i.e. a symbolic link, whose expansion points to itself.
See also
Chmod, Access, Chown (() 2)

Example
Program Example24;

{ Program to demonstrate the Chown function. }

Uses linux;

Var UID,GID : Longint;
    F : Text;
    
begin
  
  Writeln ('This will only work if you are root.');
  Write ('Enter a UID : ');readln(UID);
  Write ('Enter a GID : ');readln(GID);
  Assign (f,'test.txt');
  Rewrite (f);
  Writeln (f,'The owner of this file should become : ');
  Writeln (f,'UID : ',UID);
  Writeln (f,'GID : ',GID);
  Close (F);
  if not Chown ('test.txt',UID,GID) then
    if LinuxError=Sys_EPERM then
      Writeln ('You are not root !')
    else
      Writeln ('Chmod failed with exit code : ',LinuxError)
  else
    Writeln ('Changed owner successfully !');
end.


11.3.10 Chmod

Declaration
Function Chmod (Path : Pathstr;NewMode : Longint) : Boolean;
Description
Chmod Sets the Mode bits of the file in Path to NewMode. Newmode can be specified by 'or'-ing the following:
S_ISUID
Set user ID on execution.
S_ISGID
Set Group ID on execution.
S_ISVTX
Set sticky bit.
S_IRUSR
Read by owner.
S_IWUSR
Write by owner.
S_IXUSR
Execute by owner.
S_IRGRP
Read by group.
S_IWGRP
Write by group.
S_IXGRP
Execute by group.
S_IROTH
Read by others.
S_IWOTH
Write by others.
S_IXOTH
Execute by others.
S_IRWXO
Read, write, execute by others.
S_IRWXG
Read, write, execute by groups.
S_IRWXU
Read, write, execute by user.

Errors
Errors are returned in LinuxError.
sys_eperm
The effective UID doesn't match the ownership of the file, and is not zero. Owner or group were not specified correctly.
sys_eaccess
One of the directories in Path has no search (=execute) permission.
sys_enoent
A directory entry in Path does not exist or is a symbolic link pointing to a non-existent directory.
sys_enotdir
A directory entry in OldPath or NewPath is nor a directory.
sys_enomem
Insufficient kernel memory.
sys_erofs
The file is on a read-only filesystem.
sys_eloop
Path has a reference to a circular symbolic link, i.e. a symbolic link, whose expansion points to itself.

See also
Chown, Access, Chmod (() 2), Octal

Example
Program Example23;

{ Program to demonstrate the Chmod function. }

Uses linux;

Var F : Text;

begin
  { Create a file }
  Assign (f,'testex21');
  Rewrite (F);
  Writeln (f,'#!/bin/sh');
  Writeln (f,'echo Some text for this file');
  Close (F);
  { Octal() makes the correct number from a
    number that LOOKS octal }
  Chmod ('testex21',octal (777)); 
  { File is now executable  }
  execl ('./testex21');    
end.


11.3.11 Clone

Declaration
TCloneFunc=function(args:pointer):longint;cdecl; Clone(func:TCloneFunc;sp:pointer;flags:longint;args:pointer):longint;
Description
Clone creates a child process which is a copy of the parent process, just like Fork does. In difference with Fork, however, the child process shares some parts of it's execution context with its parent, so it is suitable for the implementation of threads: many instances of a program that share the same memory.

When the child process is created, it starts executing the function Func, and passes it Args. The return value of Func is either the explicit return value of the function, or the exit code of the child process.

The sp pointer points to the memory reserved as stack space for the child process. This address should be the top of the memory block to be used as stack.

The Flags determine the behaviour of the Clone call. The low byte of the Flags contains the number of the signal that will be sent to the parent when the child dies. This may be bitwise OR'ed with the following constants:

CLONE_VM
Parent and child share the same memory space, including memory (un)mapped with subsequent mmap calls.
CLONE_FS
Parent and child have the same view of the filesystem; the chroot, chdir and umask calls affect both processes.
CLONE_FILES
the file descriptor table of parent and child is shared.
CLONE_SIGHAND
the parent and child share the same table of signal handlers. The signal masks are different, though.
CLONE_PID
PArent and child have the same process ID.

Clone returns the process ID in the parent process, and -1 if an error occurred.

Errors
On error, -1 is returned to the parent, and no child is created.
sys_eagain
Too many processes are running.
sys_enomem
Not enough memory to create child process.
See also
Fork, clone (2)

Example
program TestC{lone};

uses
  Linux, Errors, crt;

const
  Ready : Boolean = false;
  aChar : Char    = 'a';

function CloneProc( Arg: Pointer ): LongInt; Cdecl;
begin
  WriteLn('Hello from the clone ',PChar(Arg));
  repeat
    Write(aChar);
    Select(0,0,0,0,600);
  until Ready;
  WriteLn( 'Clone finished.');
  CloneProc := 1;
end;

var
  PID : LongInt;

procedure MainProc;
begin
  WriteLn('cloned process PID: ', PID );
  WriteLn('Press <ESC> to kill ... ' );
  repeat
    Write('.');
    Select(0,0,0,0,300);
    if KeyPressed then
      case ReadKey of
        #27: Ready := true;
	'a': aChar := 'A';
	'A': aChar := 'a';
	'b': aChar := 'b';
	'B': aChar := 'B';
      end;	
  until Ready;
  WriteLn('Ready.');
end;

const
  StackSze = 16384;
  theFlags = CLONE_VM+CLONE_FS+CLONE_FILES+CLONE_SIGHAND;
  aMsg     : PChar = 'Oops !';

var
  theStack : Pointer;
  ExitStat : LongInt;

begin
  GetMem(theStack,StackSze);
  PID := Clone(@CloneProc,
               Pointer( LongInt(theStack)+StackSze),
               theFlags,
               aMsg);
  if PID < 0 then
    WriteLn('Error : ', LinuxError, ' when cloning.')
  else 
    begin
    MainProc;
    case WaitPID(0,@ExitStat,Wait_Untraced or wait_clone) of
      -1: WriteLn('error:',LinuxError,'; ',StrError(LinuxError));
       0: WriteLn('error:',LinuxError,'; ',StrError(LinuxError));
    else 
      WriteLn('Clone exited with: ',ExitStat shr 8);
    end;
    end;
  FreeMem( theStack, StackSze );
end.


11.3.12 CloseDir

Declaration
Function CloseDir (p:pdir) : integer;
Description
CloseDir closes the directory pointed to by p. It returns zero if the directory was closed succesfully, -1 otherwise.
Errors
Errors are returned in LinuxError.
See also
OpenDir, ReadDir, SeekDir, TellDir, closedir (3)
For an example, see OpenDir.


11.3.13 CreateShellArgV

Declaration
function CreateShellArgV(const prog:string):ppchar; function CreateShellArgV(const prog:Ansistring):ppchar;
Description
CreateShellArgV creates an array of 3 PChar pointers that can be used as arguments to ExecVE the first elements in the array will contain /bin/sh, the second will contain -c, and the third will contain prog.

The function returns a pointer to this array, of type PPChar.

Errors
None.
See also
Shell

Example
Program ex61;

{ Example program to demonstrate the CreateShellArgV function }

uses linux;

Var
  S: String;
  PP : PPchar;
   I : longint;
    
begin
  S:='script -a -b -c -d -e fghijk';
  PP:=CreateShellArgV(S);
  I:=0;
  If PP<>Nil then
    While PP[i]<>Nil do
      begin
      Writeln ('Got : "',PP[i],'"');
      Inc(i);
      end;
end.


11.3.14 DirName

Declaration
Function DirName (Const Path : Pathstr) : Pathstr;
Description
Returns the directory part of Path. The directory is the part of Path before the last slash, or empty if there is no slash. The last character of the result is not a slash, unless the directory is the root directory.

Errors
None.
See also
BaseName, FExpand, Dirname (1)

Example
Program Example47;

{ Program to demonstrate the DirName function. }

Uses linux;

Var S : String;

begin
  S:=FExpand(Paramstr(0));
  Writeln ('This program is in directory : ',Dirname(S));
end.


11.3.15 Dup

Declaration
Function Dup(oldfile:longint;var newfile:longint):Boolean; Function Dup(var oldfile,newfile:text):Boolean; Function Dup(var oldfile,newfile:file):Boolean;
Description
Makes NewFile an exact copy of OldFile, after having flushed the buffer of OldFile in case it is a Text file or untyped file. Due to the buffering mechanism of Pascal, this has not the same functionality as the dup (2) call in C. The internal Pascal buffers are not the same after this call, but when the buffers are flushed (e.g. after output), the output is sent to the same file. Doing an lseek will, however, work as in C, i.e. doing a lseek will change the fileposition in both files.

The function returns False in case of an error, True if successful.

Errors
In case of errors, Linuxerror is used to report errors.
sys_ebadf
OldFile hasn't been assigned.
sys_emfile
Maximum number of open files for the process is reached.
See also
Dup2, Dup (2)

Example
program Example31;

{ Program to demonstrate the Dup function. }

uses linux;

var f : text;

begin
  if not dup (output,f) then 
    Writeln ('Dup Failed !');
  writeln ('This is written to stdout.');
  writeln (f,'This is written to the dup file, and flushed');flush(f);
  writeln
end.


11.3.16 Dup2

Declaration
Function Dup2(oldfile,newfile:longint):Boolean; Function Dup2(var oldfile,newfile:text):Boolean; Function Dup2(var oldfile,newfile:file):Boolean;
Description
Makes NewFile an exact copy of OldFile, after having flushed the buffer of OldFile in the case of text or untyped files.

NewFile can be an assigned file. If newfile was open, it is closed first. Due to the buffering mechanism of Pascal, this has not the same functionality as the dup2 (2) call in C. The internal Pascal buffers are not the same after this call, but when the buffers are flushed (e.g. after output), the output is sent to the same file. Doing an lseek will, however, work as in C, i.e. doing a lseek will change the fileposition in both files.

The function returns True if succesful, false otherwise.

Errors
In case of error, Linuxerror is used to report errors.
sys_ebadf
OldFile hasn't been assigned.
sys_emfile
Maximum number of open files for the process is reached.
See also
Dup, Dup2 (2)

Example
program Example31;

{ Program to demonstrate the Dup function. }

uses linux;

var f : text;
    i : longint;
    
begin
  Assign (f,'text.txt');
  Rewrite (F);
  For i:=1 to 10 do writeln (F,'Line : ',i);
  if not dup2 (output,f) then 
    Writeln ('Dup2 Failed !');
  writeln ('This is written to stdout.');
  writeln (f,'This is written to the dup file, and flushed');
  flush(f);
  writeln;
  { Remove file. Comment this if you want to check flushing.}
  Unlink ('text.txt');
end.


11.3.17 EpochToLocal

Declaration
Procedure EpochToLocal (Epoch : Longint; var Year,Month,Day,Hour,Minute,Second : Word);
Description
Converts the epoch time (=Number of seconds since 00:00:00 , January 1, 1970, corrected for your time zone ) to local date and time.

This function takes into account the timzeone settings of your system.

Errors
None
See also
GetEpochTime, LocalToEpoch, GetTime,GetDate

Example
Program Example3;

{ Program to demonstrate the EpochToLocal function. }

Uses linux;

Var Year,month,day,hour,minute,seconds : Word;

begin
  EpochToLocal (GetEpochTime,Year,month,day,hour,minute,seconds);
  Writeln ('Current date : ',Day:2,'/',Month:2,'/',Year:4);
  Writeln ('Current time : ',Hour:2,':',minute:2,':',seconds:2);
end.


11.3.18 Execl

Declaration
Procedure Execl (Path : pathstr);
Description
Replaces the currently running program with the program, specified in path. Path is split into a command and it's options. The executable in path is NOT searched in the path. The current environment is passed to the program. On success, execl does not return.

Errors
Errors are reported in LinuxError:
sys_eacces
File is not a regular file, or has no execute permission. A compononent of the path has no search permission.
sys_eperm
The file system is mounted noexec.
sys_e2big
Argument list too big.
sys_enoexec
The magic number in the file is incorrect.
sys_enoent
The file does not exist.
sys_enomem
Not enough memory for kernel, or to split command line.
sys_enotdir
A component of the path is not a directory.
sys_eloop
The path contains a circular reference (via symlinks).
See also
Execve, Execv, Execvp, Execle, Execlp, Fork, execvp (3)

Example
Program Example10;

{ Program to demonstrate the Execl function. }

Uses linux, strings;

begin
  { Execute 'ls -l', with current environment. }
  { 'ls' is NOT looked for in PATH environment variable.}
  Execl ('/bin/ls -l');
end.


11.3.19 Execle

Declaration
Procedure Execle (Path : pathstr, Ep : ppchar);
Description
Replaces the currently running program with the program, specified in path. Path is split into a command and it's options. The executable in path is searched in the path, if it isn't an absolute filename. The environment in ep is passed to the program. On success, execle does not return.

Errors
Errors are reported in LinuxError:
sys_eacces
File is not a regular file, or has no execute permission. A compononent of the path has no search permission.
sys_eperm
The file system is mounted noexec.
sys_e2big
Argument list too big.
sys_enoexec
The magic number in the file is incorrect.
sys_enoent
The file does not exist.
sys_enomem
Not enough memory for kernel, or to split command line.
sys_enotdir
A component of the path is not a directory.
sys_eloop
The path contains a circular reference (via symlinks).
See also
Execve, Execv, Execvp, Execl, Execlp, Fork, execvp (3)

Example
Program Example11;

{ Program to demonstrate the Execle function. }

Uses linux, strings;

begin
  { Execute 'ls -l', with current environment. }
  { 'ls' is NOT looked for in PATH environment variable.}
  { envp is defined in the system unit.}
  Execle ('/bin/ls -l',envp);
end.


11.3.20 Execlp

Declaration
Procedure Execlp (Path : pathstr);
Description
Replaces the currently running program with the program, specified in path. Path is split into a command and it's options. The executable in path is searched in the path, if it isn't an absolute filename. The current environment is passed to the program. On success, execlp does not return.

Errors
Errors are reported in LinuxError:
sys_eacces
File is not a regular file, or has no execute permission. A compononent of the path has no search permission.
sys_eperm
The file system is mounted noexec.
sys_e2big
Argument list too big.
sys_enoexec
The magic number in the file is incorrect.
sys_enoent
The file does not exist.
sys_enomem
Not enough memory for kernel, or to split command line.
sys_enotdir
A component of the path is not a directory.
sys_eloop
The path contains a circular reference (via symlinks).
See also
Execve, Execv, Execvp, Execle, Execl, Fork, execvp (3)

Example
Program Example12;

{ Program to demonstrate the Execlp function. }

Uses linux, strings;

begin
  { Execute 'ls -l', with current environment. }
  { 'ls' is looked for in PATH environment variable.}
  { envp is defined in the system unit.}
  Execlp ('ls -l',envp);
end.


11.3.21 Execv

Declaration
Procedure Execv (Path : pathstr; args : ppchar);
Description
Replaces the currently running program with the program, specified in path. It gives the program the options in args. This is a pointer to an array of pointers to null-terminated strings. The last pointer in this array should be nil. The current environment is passed to the program. On success, execv does not return.

Errors
Errors are reported in LinuxError:
sys_eacces
File is not a regular file, or has no execute permission. A compononent of the path has no search permission.
sys_eperm
The file system is mounted noexec.
sys_e2big
Argument list too big.
sys_enoexec
The magic number in the file is incorrect.
sys_enoent
The file does not exist.
sys_enomem
Not enough memory for kernel.
sys_enotdir
A component of the path is not a directory.
sys_eloop
The path contains a circular reference (via symlinks).
See also
Execve, Execvp, Execle, Execl, Execlp, Fork, execv (3)

Example
Program Example8;

{ Program to demonstrate the Execv function. }

Uses linux, strings;

Const Arg0 : PChar = '/bin/ls';
      Arg1 : Pchar = '-l';
      
Var PP : PPchar;


begin
  GetMem (PP,3*SizeOf(Pchar));
  PP[0]:=Arg0;
  PP[1]:=Arg1;
  PP[3]:=Nil;
  { Execute '/bin/ls -l', with current environment }
  Execv ('/bin/ls',pp);
end.


11.3.22 Execve

Declaration
Procedure Execve(Path:pchar;args:ppchar;ep:ppchar); Procedure Execve (Path : pathstr; args,ep : ppchar);
Description
Replaces the currently running program with the program, specified in path. It gives the program the options in args, and the environment in ep. They are pointers to an array of pointers to null-terminated strings. The last pointer in this array should be nil. On success, execve does not return.
Errors
Errors are reported in LinuxError:
eacces
File is not a regular file, or has no execute permission. A compononent of the path has no search permission.
sys_ eperm
The file system is mounted noexec.
sys_ e2big
Argument list too big.
sys_ enoexec
The magic number in the file is incorrect.
sys_ enoent
The file does not exist.
sys_ enomem
Not enough memory for kernel.
sys_ enotdir
A component of the path is not a directory.
sys_ eloop
The path contains a circular reference (via symlinks).
See also
Execve, Execv, Execvp Execle, Execl, Execlp, Fork, execve (2)

Example
Program Example7;

{ Program to demonstrate the Execve function. }

Uses linux, strings;

Const Arg0 : PChar = '/bin/ls';
      Arg1 : Pchar = '-l';
      
Var PP : PPchar;


begin
  GetMem (PP,3*SizeOf(Pchar));
  PP[0]:=Arg0;
  PP[1]:=Arg1;
  PP[3]:=Nil;
  { Execute '/bin/ls -l', with current environment }
  { Envp is defined in system.inc }
  ExecVe ('/bin/ls',pp,envp);
end.


11.3.23 Execvp

Declaration
Procedure Execvp (Path : pathstr; args : ppchar);
Description
Replaces the currently running program with the program, specified in path. The executable in path is searched in the path, if it isn't an absolute filename. It gives the program the options in args. This is a pointer to an array of pointers to null-terminated strings. The last pointer in this array should be nil. The current environment is passed to the program. On success, execvp does not return.

Errors
Errors are reported in LinuxError:
sys_eacces
File is not a regular file, or has no execute permission. A compononent of the path has no search permission.
sys_eperm
The file system is mounted noexec.
sys_e2big
Argument list too big.
sys_enoexec
The magic number in the file is incorrect.
sys_enoent
The file does not exist.
sys_enomem
Not enough memory for kernel.
sys_enotdir
A component of the path is not a directory.
sys_eloop
The path contains a circular reference (via symlinks).
See also
Execve, Execv, Execle, Execl, Execlp, Fork, execvp (3)

Example
Program Example9;

{ Program to demonstrate the Execvp function. }

Uses linux, strings;

Const Arg0 : PChar = 'ls';
      Arg1 : Pchar = '-l';
      
Var PP : PPchar;


begin
  GetMem (PP,3*SizeOf(Pchar));
  PP[0]:=Arg0;
  PP[1]:=Arg1;
  PP[3]:=Nil;
  { Execute 'ls -l', with current environment. }
  { 'ls' is looked for in PATH environment variable.}
  { Envp is defined in the system unit. }
  Execvp ('ls',pp,envp);
end.


11.3.24 FD_ZERO

Declaration
Procedure FD_ZERO (var fds:fdSet);
Description
FD_ZERO clears all the filedescriptors in the file descriptor set fds.
Errors
None.
See also
Select, SelectText, GetFS, FD_Clr, FD_Set, FD_IsSet

For an example, see Select.


11.3.25 FD_Clr

Declaration
Procedure FD_Clr (fd:longint;var fds:fdSet);
Description
FD_Clr clears file descriptor fd in filedescriptor s et fds.
Errors
None.
See also
Select, SelectText, GetFS, FD_ZERO, FD_Set, FD_IsSet

For an example, see Select.


11.3.26 FD_IsSet

Declaration
Function FD_IsSet (fd:longint;var fds:fdSet) : boolean;
Description
FD_Set Checks whether file descriptor fd in filedescriptor set fds is set.
Errors
None.
See also
Select, SelectText, GetFS, FD_ZERO, FD_Clr, FD_Set

For an example, see Select.


11.3.27 FD_Set

Declaration
Procedure FD_Set (fd:longint;var fds:fdSet);
Description
FD_Set sets file descriptor fd in filedescriptor set fds.
Errors
None.
See also
Select, SelectText, GetFS,FD_ZERO, FD_Clr, FD_IsSet

For an example, see Select.


11.3.28 fdClose

Declaration
Function fdClose (fd:longint) : boolean;
Description
fdClose closes a file with file descriptor Fd. The function returns True if the file was closed successfully, False otherwise.

Errors
Errors are returned in LinuxError
See also
fdOpen, fdRead, fdWrite,fdTruncate, fdFlush, seefFdSeek
For an example, see fdOpen.


11.3.29 fdFlush

Declaration
Function fdFlush (fd:Longint) : boolean;
Description
fdflush flushes the Linux kernel file buffer, so the file is actually written to disk. This is NOT the same as the internal buffer, maintained by Free Pascal. The function returns True if the call was successful, false if an error occurred.
Errors
Errors are returned in LinuxError.
See also
fdOpen, fdClose, fdRead,fdWrite, fdTruncate, fdSeek
For an example, see fdRead.


11.3.30 fdOpen

Declaration
Function fdOpen(PathName:String;flags:longint):longint; Function fdOpen(PathName:Pchar ;flags:longint):longint; Function fdOpen(PathName:String;flags,mode:longint):longint; Function fdOpen(PathName:Pchar ;flags,mode:longint):longint;
Description
fdOpen opens a file in PathName with flags flags One of the following:
Open_RdOnly
File is opened Read-only.
Open_WrOnly
File is opened Write-only.
Open_RdWr
File is opened Read-Write.
The flags may beOR-ed with one of the following constants:
Open_Accmode
File is opened
Open_Creat
File is created if it doesn't exist.
Open_Excl
If the file is opened with Open_Creat and it already exists, the call wil fail.
Open_NoCtty
If the file is a terminal device, it will NOT become the process' controlling terminal.
Open_Trunc
If the file exists, it will be truncated.
Open_Append
the file is opened in append mode. Before each write, the file pointer is positioned at the end of the file.
Open_NonBlock
The file is opened in non-blocking mode. No operation on the file descriptor will cause the calling process to wait till.
Open_NDelay
Idem as Open_NonBlock
Open_Sync
The file is opened for synchronous IO. Any write operation on the file will not return untill the data is physically written to disk.
Open_NoFollow
if the file is a symbolic link, the open fails. (LINUX 2.1.126 and higher only)
Open_Directory
if the file is not a directory, the open fails. (LINUX 2.1.126 and higher only)
PathName can be of type PChar or String. The optional mode argument specifies the permissions to set when opening the file. This is modified by the umask setting. The real permissions are Mode and not umask. The return value of the function is the filedescriptor, or a negative value if there was an error.

Errors
Errors are returned in LinuxError
See also
fdClose, fdRead, fdWrite,fdTruncate, fdFlush, fdSeek

Example
Program Example19;

{ Program to demonstrate the fdOpen, fdwrite and fdCLose functions. }

Uses linux;

Const Line : String[80] = 'This is easy writing !';

Var FD : Longint;

begin
  FD:=fdOpen ('Test.dat',Open_WrOnly or Open_Creat);
  if FD>0 then
    begin
    if length(Line)<>fdwrite (FD,Line[1],Length(Line)) then
      Writeln ('Error when writing to file !');
    fdClose(FD);
    end;
end.


11.3.31 fdRead

Declaration
Function fdRead (fd:longint;var buf;size:longint) : longint;
Description
fdRead reads at most size bytes from the file descriptor fd, and stores them in buf. The function returns the number of bytes actually read, or -1 if an error occurred. No checking on the length of buf is done.

Errors
Errors are returned in LinuxError.
See also
fdOpen, fdClose, fdWrite,fdTruncate, fdFlush, fdSeek

Example
Program Example20;

{ Program to demonstrate the fdRead and fdTruncate functions. }

Uses linux;

Const Data : string[10] = '12345687890';

Var FD : Longint;
    l : longint;
        
begin
  FD:=fdOpen('test.dat',open_wronly or open_creat,octal(666));
  if fd>0 then
    begin
    { Fill file with data } 
    for l:=1 to 10 do
      if fdWrite (FD,Data[1],10)<>10 then
        begin
        writeln ('Error when writing !');
        halt(1);
        end;
    fdClose(FD);
    FD:=fdOpen('test.dat',open_rdonly);
    { Read data again }
    If FD>0 then
      begin
      For l:=1 to 5 do 
        if fdRead (FD,Data[1],10)<>10 then
          begin
          Writeln ('Error when Reading !');
          Halt(2);
          end;
      fdCLose(FD);
      { Truncating file at 60 bytes }
      { For truncating, file must be open or write }    
      FD:=fdOpen('test.dat',open_wronly,octal(666));
      if FD>0 then
        begin 
        if not fdTruncate(FD,60) then
           Writeln('Error when truncating !');
        fdClose (FD);
        end;
      end;
    end;
end.


11.3.32 fdSeek

Declaration
Function fdSeek (fd,Pos,SeekType:longint) : longint;
Description
fdSeek sets the current fileposition of file fd to Pos, starting from SeekType, which can be one of the following:
Seek_Set
Pos is the absolute position in the file.
Seek_Cur
Pos is relative to the current position.
Seek_end
Pos is relative to the end of the file.
The function returns the new fileposition, or -1 of an error occurred.

Errors
Errors are returned in LinuxError.
See also
fdOpen, fdWrite, fdClose, fdRead,fdTruncate, fdFlush
For an example, see fdOpen.


11.3.33 fdTruncate

Declaration
Function fdTruncate (fd,size:longint) : boolean;
Description
fdTruncate sets the length of a file in fd on size bytes, where size must be less than or equal to the current length of the file in fd. The function returns True if the call was successful, false if an error occurred.
Errors
Errors are returned in LinuxError.
See also
fdOpen, fdClose, fdRead,fdWrite,fdFlush, fdSeek


11.3.34 fdWrite

Declaration
Function fdWrite (fd:longint;var buf;size:longint) : longint;
Description
fdWrite writes at most size bytes from buf to file descriptor fd. The function returns the number of bytes actually written, or -1 if an error occurred.

Errors
Errors are returned in LinuxError.
See also
fdOpen, fdClose, fdRead,fdTruncate, fdSeek, fdFlush


11.3.35 FExpand

Declaration
Function FExpand (Const Path: Pathstr) : pathstr;
Description
Expands Path to a full path, starting from root, eliminating directory references such as . and .. from the result.

Errors
None
See also
BaseName,DirName

Example
Program Example45;

{ Program to demonstrate the FExpand function. }

Uses linux;

begin
  Writeln ('This program is in : ',FExpand(Paramstr(0)));
end.


11.3.36 FLock

Declaration
Function Flock (fd,mode : longint) : boolean; Function Flock (var T : text;mode : longint) : boolean; Function Flock (var F : File;mode : longint) : boolean;
Description
FLock implements file locking. it sets or removes a lock on the file F. F can be of type Text or File, or it can be a LINUX filedescriptor (a longint) Mode can be one of the following constants :
LOCK_SH
sets a shared lock.
LOCK_EX
sets an exclusive lock.
LOCK_UN
unlocks the file.
LOCK_NB
This can be OR-ed together with the other. If this is done the application doesn't block when locking.

The function returns True if successful, False otherwise.

Errors
If an error occurs, it is reported in LinuxError.
See also
Fcntl, flock (2)


11.3.37 FNMatch

Declaration
Function FNMatch(const Pattern,Name:string):Boolean;
Description
FNMatch returns True if the filename in Name matches the wildcard pattern in Pattern, False otherwise.

Pattern can contain the wildcards * (match zero or more arbitrary characters) or ? (match a single character).

Errors
None.
See also
FSearch, FExpand

Example
Program Example69;

{ Program to demonstrate the FNMatch function. }

Uses linux;

  Procedure TestMatch(Pattern,Name : String);
  
  begin
    Write ('"',Name,'" ');
    If FNMatch (Pattern,Name) then
      Write ('matches')
    else
      Write ('does not match');
    Writeln(' "',Pattern,'".');
  end;
  
begin
  TestMatch('*','FileName');
  TestMatch('.*','FileName');
  TestMatch('*a*','FileName');
  TestMatch('?ile*','FileName');
  TestMatch('?','FileName');
  TestMatch('.?','FileName');
  TestMatch('?a*','FileName');
  TestMatch('??*me?','FileName');
end.


11.3.38 FSearch

Declaration
Function FSearch (Path : pathstr;DirList : string) : Pathstr;
Description
Searches in DirList, a colon separated list of directories, for a file named Path. It then returns a path to the found file.
Errors
An empty string if no such file was found.
See also
BaseName, DirName, FExpand, FNMatch

Example
Program Example46;

{ Program to demonstrate the FSearch function. }

Uses linux,strings;

begin
  Writeln ('ls is in : ',FSearch ('ls',strpas(Getenv('PATH'))));
end.


11.3.39 FSplit

Declaration
Procedure FSplit(const Path:PathStr;
Var Dir:DirStr;Var Name:NameStr;Var Ext:ExtStr);
Description
FSplit splits a full file name into 3 parts : A Path, a Name and an extension (in ext). The extension is taken to be all letters after the last dot (.).
Errors
None.
See also
FSearch

Example
Program Example67;

uses Linux;

{ Program to demonstrate the FSplit function. }

var
  Path,Name,Ext : string;
  
begin
  FSplit(ParamStr(1),Path,Name,Ext);
  WriteLn('Split ',ParamStr(1),' in:');
  WriteLn('Path     : ',Path);
  WriteLn('Name     : ',Name);
  WriteLn('Extension: ',Ext);
end.


11.3.40 FSStat

Declaration
Function FSStat (Path : Pathstr; Var Info : statfs) : Boolean; Function FSStat (Fd:longint;Var Info:stat) : Boolean;
Description
Return in Info information about the filesystem on which the file Path resides, or on which the file with file descriptor fd resides. Info is of type statfs. The function returns True if the call was succesfull, False if the call failed.
Errors
LinuxError is used to report errors.
sys_enotdir
A component of Path is not a directory.
sys_einval
Invalid character in Path.
sys_enoent
Path does not exist.
sys_eaccess
Search permission is denied for component in Path.
sys_eloop
A circular symbolic link was encountered in Path.
sys_eio
An error occurred while reading from the filesystem.

See also
FStat, LStat, statfs (2)

Example
program Example30;

{ Program to demonstrate the FSStat function. }

uses linux;
    
var s : string; 
    info : statfs;
    
begin
  writeln ('Info about current partition : ');
  s:='.';
  while s<>'q' do 
    begin
    if not fsstat (s,info) then
       begin
       writeln('Fstat failed. Errno : ',linuxerror);
       halt (1);
       end;
    writeln;
    writeln ('Result of fsstat on file ''',s,'''.');
    writeln ('fstype  : ',info.fstype);
    writeln ('bsize   : ',info.bsize);
    writeln ('bfree   : ',info.bfree);
    writeln ('bavail  : ',info.bavail);
    writeln ('files   : ',info.files);
    writeln ('ffree   : ',info.ffree);
    writeln ('fsid    : ',info.fsid);
    writeln ('Namelen : ',info.namelen);
    write ('Type name of file to do fsstat. (q quits) :');
    readln (s)
    end;
end.


11.3.41 FStat

Declaration
Function FStat(Path:Pathstr;Var Info:stat):Boolean; Function FStat(Fd:longint;Var Info:stat):Boolean; Function FStat(var F:Text;Var Info:stat):Boolean; Function FStat(var F:File;Var Info:stat):Boolean;
Description
FStat gets information about the file specified in one of the following:
Path
a file on the filesystem.
Fd
a valid file descriptor.
F
an opened text file or untyped file.
and stores it in Info, which is of type stat. The function returns True if the call was succesfull, False if the call failed.

Errors
LinuxError is used to report errors.
sys_enoent
Path does not exist.
See also
FSStat, LStat, stat (2)

Example
program example28;

{ Program to demonstrate the FStat function. }

uses linux;
    
var f : text;    
    i : byte;
    info : stat;
    
begin
  { Make a file }
  assign (f,'test.fil');
  rewrite (f);
  for i:=1 to 10 do writeln (f,'Testline # ',i);
  close (f);
  { Do the call on made file. }
  if not fstat ('test.fil',info) then 
     begin
     writeln('Fstat failed. Errno : ',linuxerror);
     halt (1);
     end;
  writeln;
  writeln ('Result of fstat on file ''test.fil''.');
  writeln ('Inode   : ',info.ino);
  writeln ('Mode    : ',info.mode);
  writeln ('nlink   : ',info.nlink);
  writeln ('uid     : ',info.uid);
  writeln ('gid     : ',info.gid);
  writeln ('rdev    : ',info.rdev);
  writeln ('Size    : ',info.size);
  writeln ('Blksize : ',info.blksze);
  writeln ('Blocks  : ',info.blocks);
  writeln ('atime   : ',info.atime);
  writeln ('mtime   : ',info.mtime);
  writeln ('ctime   : ',info.ctime);
  { Remove file }  
  erase (f);    
end.


11.3.42 Fcntl

Declaration
Function Fcntl(Fd:longint;Cmd:Integer):integer; Function Fcntl(var Fd:Text;Cmd:Integer):integer;
Description
Read a file's attributes. Fd is an assigned file, or a valid file descriptor. Cmd speciefies what to do, and is one of the following:
F_GetFd
Read the close_on_exec flag. If the low-order bit is 0, then the file will remain open across execve calls.
F_GetFl
Read the descriptor's flags.
F_GetOwn
Get the Process ID of the owner of a socket.

Errors
LinuxError is used to report errors.
sys_ebadf
Fd has a bad file descriptor.

See also
Fcntl, Fcntl (2)


11.3.43 Fcntl

Declaration
Procedure Fcntl (Fd : text, Cmd : Integer; Arg : longint); Procedure Fcntl (Fd:longint;Cmd:longint;Arg:Longint);
Description
Read or Set a file's attributes. Fd is an assigned file or a valid file descriptor. Cmd speciefies what to do, and is one of the following:
F_SetFd
Set the close_on_exec flag of Fd. (only the least siginificant bit is used).
F_GetLk
Return the flock record that prevents this process from obtaining the lock, or set the l_type field of the lock of there is no obstruction. Arg is a pointer to a flock record.
F_SetLk
Set the lock or clear it (depending on l_type in the flock structure). if the lock is held by another process, an error occurs.
F_GetLkw
Same as for F_Setlk, but wait until the lock is released.
F_SetOwn
Set the Process or process group that owns a socket.

Errors

LinuxError is used to report errors.

sys_ebadf
Fd has a bad file descriptor.
sys_eagain or sys_eaccess
For F_SetLk, if the lock is held by another process.

See also
Fcntl, Fcntl (2) , seefFLock


11.3.44 Fork

Declaration
Function Fork : Longint;
Description
Fork creates a child process which is a copy of the parent process. Fork returns the process ID in the parent process, and zero in the child's process. (you can get the parent's PID with GetPPid).

Errors
On error, -1 is returned to the parent, and no child is created.
sys_eagain
Not enough memory to create child process.
See also
Execve, Clone, fork (2)


11.3.45 FRename

Declaration
Function FReName (OldName,NewName : Pchar) : Boolean; Function FReName (OldName,NewName : String) : Boolean;
Description
FRename renames the file OldName to NewName. NewName can be in a different directory than OldName, but it cannot be on another partition (device). Any existing file on the new location will be replaced.

If the operation fails, then the OldName file will be preserved.

The function returns True on succes, False on failure.

Errors
On error, errors are reported in LinuxError. Possible errors include:
sys_eisdir
NewName exists and is a directory, but OldName is not a directory.
sys_exdev
NewName and OldName are on different devices.
sys_enotempty or sys_eexist
NewName is an existing, non-empty directory.
sys_ebusy
OldName or NewName is a directory and is in use by another process.
sys_einval
NewName is part of OldName.
sys_emlink
OldPath or NewPath already have tha maximum amount of links pointing to them.
sys_enotdir
part of OldName or NewName is not directory.
sys_efault
For the pchar case: One of the pointers points to an invalid address.
sys_eaccess
access is denied when attempting to move the file.
sys_enametoolong
Either OldName or NewName is too long.
sys_enoent
a directory component in OldName or NewName didn't exist.
sys_enomem
not enough kernel memory.
sys_erofs
NewName or OldName is on a read-only file system.
sys_eloop
too many symbolic links were encountered trying to expand OldName or NewName
sys_enospc
the filesystem has no room for the new directory entry.
See also
UnLink


11.3.46 GetDate

Declaration
Procedure GetDate (Var Year, Month, Day : Word) ;
Description
Returns the current date.
Errors
None
See also
GetEpochTime, GetTime, GetDateTime, EpochToLocal

Example
Program Example6;

{ Program to demonstrate the GetDate function. }

Uses linux;

Var Year, Month, Day : Word;

begin
 GetDate (Year, Month, Day);
 Writeln ('Date : ',Day:2,'/',Month:2,'/',Year:4);
end.


11.3.47 GetDateTime

Declaration
Procedure GetDateTime(Var Year,Month,Day,hour,minute,second:Word);
Description
Returns the current date and time. The time is corrected for the local time zone. This procedure is equivalent to the GetDate and GetTime calls.
Errors
None
See also
GetEpochTime, GetTime, EpochToLocal, GetDate

Example
Program Example6;

{ Program to demonstrate the GetDateTime function. }

Uses linux;

Var Year, Month, Day, Hour, min, sec : Word;

begin
 GetDateTime (Year, Month, Day, Hour, min, sec);
 Writeln ('Date : ',Day:2,'/',Month:2,'/',Year:4);
 Writeln ('Time : ',Hour:2,':',Min:2,':',Sec:2);
end.


11.3.48 GetDomainName

Declaration
Function GetDomainName : String;
Description
Get the domain name of the machine on which the process is running. An empty string is returned if the domain is not set.

Errors
None.
See also
GetHostName,seemGetdomainname2

Example
Program Example39;

{ Program to demonstrate the GetDomainName function. }

Uses linux;

begin
  Writeln ('Domain name of this machine is : ',GetDomainName);
end.


11.3.49 GetEGid

Declaration
Function GetEGid : Longint;
Description
Get the effective group ID of the currently running process.
Errors
None.
See also
GetGid, getegid (2)

Example
Program Example18;

{ Program to demonstrate the GetGid and GetEGid functions. }

Uses linux;

begin
 writeln ('Group Id = ',getgid,' Effective group Id = ',getegid);
end.


11.3.50 GetEUid

Declaration
Function GetEUid : Longint;
Description
Get the effective user ID of the currently running process.
Errors
None.
See also
GetEUid, geteuid (2)

Example
Program Example17;

{ Program to demonstrate the GetUid and GetEUid functions. }

Uses linux;

begin
  writeln ('User Id = ',getuid,' Effective user Id = ',geteuid);
end.


11.3.51 GetEnv

Declaration
Function GetEnv (P : String) : PChar;
Description
Returns the value of the environment variable in P. If the variable is not defined, nil is returned. The value of the environment variable may be the empty string. A PChar is returned to accomodate for strings longer than 255 bytes, TERMCAP and LS_COLORS, for instance.

Errors
None.
See also
sh (1) , csh (1)

Example
Program Example41;

{ Program to demonstrate the GetEnv function. }

Uses linux;

begin
  Writeln ('Path is : ',Getenv('PATH'));
end.


11.3.52 GetEpochTime

Declaration
Function GetEpochTime : longint;
Description
returns the number of seconds since 00:00:00 gmt, january 1, 1970. it is adjusted to the local time zone, but not to DST.

Errors
no errors
See also
EpochToLocal, GetTime, time (2)

Example
Program Example1;

{ Program to demonstrate the GetEpochTime function. }

Uses linux;

begin
  Write ('Secs past the start of the Epoch (00:00 1/1/1980) : ');
  Writeln (GetEpochTime);
end.


11.3.53 GetFS

Declaration
Function GetFS (Var F : Any File Type) : Longint;
Description
GetFS returns the file selector that the kernel provided for your file. In principle you don' need this file selector. Only for some calls it is needed, such as the Select call or so.
Errors
In case the file was not opened, then -1 is returned.
See also
Select

Example
Program Example33;

{ Program to demonstrate the SelectText function. }

Uses linux;

Var tv : TimeVal;
    
begin
  Writeln ('Press the <ENTER> to continue the program.');
  { Wait until File descriptor 0 (=Input) changes }
  SelectText (Input,nil);
  { Get rid of <ENTER> in buffer }
  readln;
  Writeln ('Press <ENTER> key in less than 2 seconds...');
  tv.sec:=2;
  tv.usec:=0;
  if SelectText (Input,@tv)>0 then 
    Writeln ('Thank you !')
  else
    Writeln ('Too late !');
end.


11.3.54 GetGid

Declaration
Function GetGid : Longint;
Description
Get the real group ID of the currently running process.
Errors
None.
See also
GetEGid, getgid (2)

Example
Program Example18;

{ Program to demonstrate the GetGid and GetEGid functions. }

Uses linux;

begin
 writeln ('Group Id = ',getgid,' Effective group Id = ',getegid);
end.


11.3.55 GetHostName

Declaration
Function GetHostName : String;
Description
Get the hostname of the machine on which the process is running. An empty string is returned if hostname is not set.

Errors
None.
See also
GetDomainName,seemGethostname2

Example
Program Example40;

{ Program to demonstrate the GetHostName function. }

Uses linux;

begin
  Writeln ('Name of this machine is : ',GetHostName);
end.


11.3.56 GetLocalTimezone

Declaration
procedure GetLocalTimezone(timer:longint;var leap_correct,leap_hit:longint); procedure GetLocalTimezone(timer:longint);
Description
GetLocalTimeZone returns the local timezone information. It also initializes the TZSeconds variable, which is used to correct the epoch time to local time.

There should never be any need to call this function directly. It is called by the initialization routines of the Linux unit.

See also
GetTimezoneFile, ReadTimezoneFile


11.3.57 GetPid

Declaration
Function GetPid : Longint;
Description
Get the Process ID of the currently running process.
Errors
None.
See also
GetPPid, getpid (2)

Example
Program Example16;

{ Program to demonstrate the GetPid, GetPPid function. }

Uses linux;

begin
  Writeln ('Process Id = ',getpid,' Parent process Id = ',getppid);
end.


11.3.58 GetPPid

Declaration
Function GetPPid : Longint;
Description
Get the Process ID of the parent process.
Errors
None.
See also
GetPid, getppid (2)

Example
Program Example16;

{ Program to demonstrate the GetPid, GetPPid function. }

Uses linux;

begin
  Writeln ('Process Id = ',getpid,' Parent process Id = ',getppid);
end.


11.3.59 GetPriority

Declaration
Function GetPriority (Which,Who : Integer) : Integer;
Description
GetPriority returns the priority with which a process is running. Which process(es) is determined by the Which and Who variables. Which can be one of the pre-defined Prio_Process, Prio_PGrp, Prio_User, in which case Who is the process ID, Process group ID or User ID, respectively.

Errors

Error checking must be done on LinuxError, since a priority can be negative.

sys_esrch
No process found using which and who.
sys_einval
Which was not one of Prio_Process, Prio_Grp or Prio_User.

See also
SetPriority, Nice, Getpriority (2)
For an example, see Nice.


11.3.60 GetTime

Declaration
procedure GetTime(var hour,min,sec,msec,usec:word); procedure GetTime(var hour,min,sec,sec100:word); procedure GetTime(var hour,min,sec:word);
Description
Returns the current time of the day, adjusted to local time. Upon return, the parameters are filled with
hour
Hours since 00:00 today.
min
minutes in current hour.
sec
seconds in current minute.
sec100
hundreds of seconds in current second.
msec
milliseconds in current second.
usec
microseconds in current second.
Errors
None
See also
GetEpochTime, GetDate, GetDateTime, EpochToLocal

Example
Program Example5;

{ Program to demonstrate the GetTime function. }

Uses linux;

Var Hour, Minute, Second : Word;

begin
  GetTime (Hour, Minute, Second);
  Writeln ('Time : ',Hour:2,':',Minute:2,':',Second:2);
end.


11.3.61 GetTimeOfDay

Declaration
Procedure GetTimeOfDay(var tv:timeval);
Description
GetTimeOfDay returns the number of seconds since 00:00, January 1 1970, GMT in a timeval record. This time NOT corrected any way, not taking into account timezones, daylight savings time and so on.

It is simply a wrapper to the kernel system call. To get the local time, GetTime.

Errors
None.
See also
GetTime, GetTimeOfDay


11.3.62 GetTimeOfDay

Declaration
Function GetTimeOfDay:longint;
Description
GetTimeOfDay returns the number of seconds since 00:00, January 1 1970, GMT. This time NOT corrected any way, not taking into account timezones, daylight savings time and so on.

It is simply a wrapper to the kernel system call. To get the local time, GetTime.

Errors
None.
See also
GetTimeOfDay, GetTime


11.3.63 GetTimezoneFile

Declaration
function GetTimezoneFile:string;
Description
GetTimezoneFile returns the location of the current timezone file. The location of file is determined as follows:
  1. If /etc/timezone exists, it is read, and the contents of this file is returned. This should work on Debian systems.
  2. If /usr/lib/zoneinfo/localtime exists, then it is returned. (this file is a symlink to the timezone file on SuSE systems)
  3. If /etc/localtime exists, then it is returned. (this file is a symlink to the timezone file on RedHat systems)
Errors
If no file was found, an empty string is returned.
See also
ReadTimezoneFile


11.3.64 GetUid

Declaration
Function GetUid : Longint;
Description
Get the real user ID of the currently running process.
Errors
None.
See also
GetEUid, getuid (2)

Example
Program Example17;

{ Program to demonstrate the GetUid and GetEUid functions. }

Uses linux;

begin
  writeln ('User Id = ',getuid,' Effective user Id = ',geteuid);
end.


11.3.65 Glob

Declaration
Function Glob (Const Path : Pathstr) : PGlob;
Description
Glob returns a pointer to a glob structure which contains all filenames which exist and match the pattern in Path. The pattern can contain wildcard characters, which have their usual meaning.

Errors
Returns nil on error, and LinuxError is set.
sys_enomem
No memory on heap for glob structure.
others
As returned by the opendir call, and sys_readdir.

See also
GlobFree, Glob (3)

Example
Program Example49;

{ Program to demonstrate the Glob and GlobFree functions. }

Uses linux;

Var G1,G2 : PGlob;

begin
  G1:=Glob ('*');
  if LinuxError=0 then
    begin
    G2:=G1;
    Writeln ('Files in this directory : ');
    While g2<>Nil do
      begin
      Writeln (g2^.name);
      g2:=g2^.next;
      end;
    GlobFree (g1);
    end;
end.


11.3.66 GlobFree

Declaration
Procedure GlobFree (Var P : Pglob);
Description
Releases the memory, occupied by a pglob structure. P is set to nil.
Errors
None
See also
Glob
For an example, see Glob.


11.3.67 IOCtl

Declaration
Procedure IOCtl (Handle,Ndx: Longint; Data: Pointer);
Description
This is a general interface to the Unix/ LINUX ioctl call. It performs various operations on the filedescriptor Handle. Ndx describes the operation to perform. Data points to data needed for the Ndx function. The structure of this data is function-dependent, so we don't elaborate on this here. For more information on this, see various manual pages under linux.

Errors

Errors are reported in LinuxError. They are very dependent on the used function, that's why we don't list them here

See also
ioctl (2)

Example
Program Example54;

uses Linux;

{ Program to demonstrate the IOCtl function. }

var
  tios : Termios;
begin
  IOCtl(1,TCGETS,@tios);
  WriteLn('Input Flags  : $',hexstr(tios.c_iflag,8));
  WriteLn('Output Flags : $',hexstr(tios.c_oflag,8));
  WriteLn('Line Flags   : $',hexstr(tios.c_lflag,8));
  WriteLn('Control Flags: $',hexstr(tios.c_cflag,8));
end.


11.3.68 IOperm

Declaration
Function IOperm (From,Num : Cadinal; Value : Longint) : boolean;
Description
IOperm sets permissions on Num ports starting with port From to Value. The function returns True if the call was successfull, False otherwise. Remark:

Errors
Errors are returned in LinuxError
See also
ioperm (2)


11.3.69 IsATTY

Declaration
Function IsATTY (var f) : Boolean;
Description
Check if the filehandle described by f is a terminal. f can be of type
  1. longint for file handles;
  2. Text for text variables such as input etc.
Returns True if f is a terminal, False otherwise.

Errors
No errors are reported
See also
IOCtl,TTYName


11.3.70 S_ISBLK

Declaration
Function S_ISBLK (m:integer) : boolean;
Description
S_ISBLK checks the file mode m to see whether the file is a block device file. If so it returns True.

Errors
FStat, S_ISLNK, S_ISREG, S_ISDIR, S_ISCHR, S_ISFIFO, S_ISSOCK

See also
ISLNK.


11.3.71 S_ISCHR

Declaration
Function S_ISCHR (m:integer) : boolean;
Description
S_ISCHR checks the file mode m to see whether the file is a character device file. If so it returns True.

Errors
FStat, S_ISLNK, S_ISREG, S_ISDIR, S_ISBLK, S_ISFIFO, S_ISSOCK

See also
ISLNK.


11.3.72 S_ISDIR

Declaration
Function S_ISDIR (m:integer) : boolean;
Description
S_ISDIR checks the file mode m to see whether the file is a directory. If so it returns True

Errors
FStat, S_ISLNK, S_ISREG, S_ISCHR, S_ISBLK, S_ISFIFO, S_ISSOCK

See also
ISLNK.


11.3.73 S_ISFIFO

Declaration
Function S_ISFIFO (m:integer) : boolean;
Description
S_ISFIFO checks the file mode m to see whether the file is a fifo (a named pipe). If so it returns True.

Errors
FStat, S_ISLNK, S_ISREG, S_ISDIR, S_ISCHR, S_ISBLK, S_ISSOCK

See also
ISLNK.


11.3.74 S_ISLNK

Declaration
Function S_ISLNK (m:integer) : boolean;
Description
S_ISLNK checks the file mode m to see whether the file is a symbolic link. If so it returns True

Errors
FStat, S_ISREG, S_ISDIR, S_ISCHR, S_ISBLK, S_ISFIFO, S_ISSOCK

See also

Example
Program Example53;

{ Program to demonstrate the S_ISLNK function. }

Uses linux;

Var Info : Stat;

begin
  if LStat (paramstr(1),info) then
    begin
    if S_ISLNK(info.mode) then 
      Writeln ('File is a link');
    if S_ISREG(info.mode) then 
      Writeln ('File is a regular file');
    if S_ISDIR(info.mode) then 
      Writeln ('File is a directory');
    if S_ISCHR(info.mode) then 
      Writeln ('File is a character device file');
    if S_ISBLK(info.mode) then 
      Writeln ('File is a block device file');
    if S_ISFIFO(info.mode) then 
      Writeln ('File is a named pipe (FIFO)');
    if S_ISSOCK(info.mode) then 
      Writeln ('File is a socket');
    end;
end.


11.3.75 S_ISREG

Declaration
Function S_ISREG (m:integer) : boolean;
Description
S_ISREG checks the file mode m to see whether the file is a regular file. If so it returns True

Errors
FStat, S_ISLNK, S_ISDIR, S_ISCHR, S_ISBLK, S_ISFIFO, S_ISSOCK

See also
ISLNK.


11.3.76 S_ISSOCK

Declaration
Function S_ISSOCK (m:integer) : boolean;
Description
S_ISSOCK checks the file mode m to see whether the file is a socket. If so it returns True.

Errors
FStat, S_ISLNK, S_ISREG, S_ISDIR, S_ISCHR, S_ISBLK, S_ISFIFO

See also
ISLNK.


11.3.77 Kill

Declaration
Function Kill (Pid : Longint; Sig : Integer) : Integer;
Description
Send a signal Sig to a process or process group. If Pid>0 then the signal is sent to Pid, if it equals -1, then the signal is sent to all processes except process 1. If Pid<-1 then the signal is sent to process group -Pid. The return value is zero, except in case three, where the return value is the number of processes to which the signal was sent.

Errors
LinuxError is used to report errors:
sys_einval
An invalid signal is sent.
sys_esrch
The Pid or process group don't exist.
sys_eperm
The effective userid of the current process doesn't math the one of process Pid.

See also
SigAction, Signal, Kill (2)


11.3.78 LStat

Declaration
Function LStat (Path : Pathstr; Var Info : stat) : Boolean;
Description
LStat gets information about the link specified in Path, and stores it in Info, which is of type stat. Contrary to FStat, it stores information about the link, not about the file the link points to. The function returns True if the call was succesfull, False if the call failed.

Errors
LinuxError is used to report errors.
sys_enoent
Path does not exist.

See also
FStat, FSStat, stat (2)

Example
program example29;

{ Program to demonstrate the LStat function. }

uses linux;
    
var f : text;    
    i : byte;
    info : stat;
    
begin
  { Make a file }
  assign (f,'test.fil');
  rewrite (f);
  for i:=1 to 10 do writeln (f,'Testline # ',i);
  close (f);
  { Do the call on made file. }
  if not fstat ('test.fil',info) then 
     begin
     writeln('Fstat failed. Errno : ',linuxerror);
     halt (1);
     end;
  writeln;
  writeln ('Result of fstat on file ''test.fil''.');
  writeln ('Inode   : ',info.ino);
  writeln ('Mode    : ',info.mode);
  writeln ('nlink   : ',info.nlink);
  writeln ('uid     : ',info.uid);
  writeln ('gid     : ',info.gid);
  writeln ('rdev    : ',info.rdev);
  writeln ('Size    : ',info.size);
  writeln ('Blksize : ',info.blksze);
  writeln ('Blocks  : ',info.blocks);
  writeln ('atime   : ',info.atime);
  writeln ('mtime   : ',info.mtime);
  writeln ('ctime   : ',info.ctime);

  If not SymLink ('test.fil','test.lnk') then
    writeln ('Link failed ! Errno :',linuxerror);

  if not lstat ('test.lnk',info) then 
     begin
     writeln('LStat failed. Errno : ',linuxerror);
     halt (1);
     end;
  writeln;
  writeln ('Result of fstat on file ''test.lnk''.');
  writeln ('Inode   : ',info.ino);
  writeln ('Mode    : ',info.mode);
  writeln ('nlink   : ',info.nlink);
  writeln ('uid     : ',info.uid);
  writeln ('gid     : ',info.gid);
  writeln ('rdev    : ',info.rdev);
  writeln ('Size    : ',info.size);
  writeln ('Blksize : ',info.blksze);
  writeln ('Blocks  : ',info.blocks);
  writeln ('atime   : ',info.atime);
  writeln ('mtime   : ',info.mtime);
  writeln ('ctime   : ',info.ctime);
  { Remove file and link }  
  erase (f);
  unlink ('test.lnk');    
end.


11.3.79 Link

Declaration
Function Link (OldPath,NewPath : pathstr) : Boolean;
Description
Link makes NewPath point to the same file als OldPath. The two files then have the same inode number. This is known as a 'hard' link. The function returns True if the call was succesfull, False if the call failed.

Errors
Errors are returned in LinuxError.
sys_exdev
OldPath and NewPath are not on the same filesystem.
sys_eperm
The filesystem containing oldpath and newpath doesn't support linking files.
sys_eaccess
Write access for the directory containing Newpath is disallowed, or one of the directories in OldPath or NewPath has no search (=execute) permission.
sys_enoent
A directory entry in OldPath or NewPath does not exist or is a symbolic link pointing to a non-existent directory.
sys_enotdir
A directory entry in OldPath or NewPath is nor a directory.
sys_enomem
Insufficient kernel memory.
sys_erofs
The files are on a read-only filesystem.
sys_eexist
NewPath already exists.
sys_emlink
OldPath has reached maximal link count.
sys_eloop
OldPath or NewPath has a reference to a circular symbolic link, i.e. a symbolic link, whose expansion points to itself.
sys_enospc
The device containing NewPath has no room for anothe entry.
sys_eperm
OldPath points to . or .. of a directory.

See also
SymLink, UnLink, Link (2)

Example
Program Example21;

{ Program to demonstrate the Link and UnLink functions. }

Uses linux;

Var F : Text;
    S : String;
begin
  Assign (F,'test.txt');
  Rewrite (F);
  Writeln (F,'This is written to test.txt');
  Close(f);
  { new.txt and test.txt are now the same file }
  if not Link ('test.txt','new.txt') then
    writeln ('Error when linking !');
  { Removing test.txt still leaves new.txt }
  If not Unlink ('test.txt') then
    Writeln ('Error when unlinking !');
  Assign (f,'new.txt');
  Reset (F);
  While not EOF(f) do 
    begin
    Readln(F,S);
    Writeln ('> ',s);
    end;
 Close (f);
 { Remove new.txt also }
 If not Unlink ('new.txt') then
   Writeln ('Error when unlinking !');
end.


11.3.80 LocalToEpoch

Declaration
Function LocalToEpoch (Year,Month,Day,Hour,Minute,Second : Word) : longint;
Description
Converts the Local time to epoch time (=Number of seconds since 00:00:00 , January 1, 1970 ).

Errors
None
See also
GetEpochTime, EpochToLocal, GetTime,GetDate

Example
Program Example4;

{ Program to demonstrate the LocalToEpoch function. }

Uses linux;

Var year,month,day,hour,minute,second : Word;

begin
  Write ('Year    : ');readln(Year);
  Write ('Month   : ');readln(Month);
  Write ('Day     : ');readln(Day);
  Write ('Hour    : ');readln(Hour);
  Write ('Minute  : ');readln(Minute);
  Write ('Seonds  : ');readln(Second);
  Write ('This is : ');
  Write (LocalToEpoch(year,month,day,hour,minute,second));
  Writeln (' seconds past 00:00 1/1/1980');
end.


11.3.81 MkFifo

Declaration
Function MkFifo (PathName: String; Mode : Longint) : Boolean;
Description
MkFifo creates named a named pipe in the filesystem, with name PathName and mode Mode.

Errors
LinuxError is used to report errors:
sys_emfile
Too many file descriptors for this process.
sys_enfile
The system file table is full.

See also
POpen, MkFifo, mkfifo (4)


11.3.82 MMap

Declaration
Function MMap(const m:tmmapargs):longint;
Description
MMap maps or unmaps files or devices into memory. The different fields of the argument m determine what and how the mmap maps this:
address
Address where to mmap the device. This address is a hint, and may not be followed.
size
Size (in bytes) of area to be mapped.
prot
Protection of mapped memory. This is a OR-ed combination of the following constants:
PROT_EXEC
The memory can be executed.
PROT_READ
The memory can be read.
PROT_WRITE
The memory can be written.
PROT_NONE
The memory can not be accessed.
flags
Contains some options for the mmap call. It is an OR-ed combination of the following constants:
MAP_FIXED
Do not map at another address than the given address. If the address cannot be used, MMap will fail.
MAP_SHARED
Share this map with other processes that map this object.
MAP_PRIVATE
Create a private map with copy-on-write semantics.
MAP_ANONYMOUS
fd does not have to be a file descriptor.
One of the options MAP_SHARED and MAP_PRIVATE must be present, but not both at the same time.
fd
File descriptor from which to map.
offset
Offset to be used in file descriptor fd.

The function returns a pointer to the mapped memory, or a -1 in case of en error.

Errors
On error, -1 is returned and LinuxError is set to the error code:
Sys_EBADF
fd is not a valid file descriptor and MAP_ANONYMOUS was not specified.
Sys_EACCES
MAP_PRIVATE was specified, but fd is not open for reading. Or MAP_SHARED was asked and PROT_WRITE is set, fd is not open for writing
Sys_EINVAL
One of the record fields Start, length or offset is invalid.
Sys_ETXTBUSY
MAP_DENYWRITE was set but the object specified by fd is open for writing.
Sys_EAGAIN
fd is locked, or too much memory is locked.
Sys_ENOMEM
Not enough memory for this operation.
See also
MUnMap, mmap (2)

Example
Program Example66;

{ Program to demonstrate the MMap function. }

Uses linux;

Var S : String;
    fd,Len : Longint;
    args : tmmapargs;
    P : PChar;
        
begin
  S:='This is a string'#0;
  Len:=Length(S);
  fd:=fdOpen('testfile.txt',Open_wrOnly or open_creat);
  If fd=-1 then 
    Halt(1);
  If fdWrite(fd,S[1],Len)=-1 then
    Halt(2);
  fdClose(fd);
  fdOpen('testfile.txt',Open_rdOnly);
  if fd=-1 then
    Halt(3);
  args.address:=0;
  args.offset:=0;
  args.size:=Len+1;
  args.fd:=Fd;
  args.flags:=MAP_PRIVATE;
  args.prot:=PROT_READ or PROT_WRITE;
  P:=Pchar(mmap(args));
  If longint(P)=-1 then
    Halt(4);
  Writeln('Read in memory  :',P);
  fdclose(fd);
  if Not MUnMap(P,Len) Then
    Halt(LinuxError);
end.


11.3.83 MUnMap

Declaration
function MUnMap (P : Pointer; Size : Longint) : Boolean;
Description
MUnMap unmaps the memory block of size Size, pointed to by P, which was previously allocated with MMap.

The function returns True if successful, False otherwise.

Errors
In case of error the function returns False and LinuxError is set to an error value. See MMap for possible error values.
See also
MMap, munmap (2)

For an example, see MMap.


11.3.84 Nice

Declaration
Procedure Nice ( N : Integer);
Description
Nice adds -N to the priority of the running process. The lower the priority numerically, the less the process is favored. Only the superuser can specify a negative N, i.e. increase the rate at which the process is run.

Errors
Errors are returned in LinuxError
sys_eperm
A non-superuser tried to specify a negative N, i.e. do a priority increase.

See also
GetPriority, SetPriority, Nice (2)

Example
Program Example15;

{ Program to demonstrate the Nice and Get/SetPriority functions. }

Uses linux;

begin
  writeln ('Setting priority to 5');
  setpriority (prio_process,getpid,5);
  writeln ('New priority = ',getpriority (prio_process,getpid));
  writeln ('Doing nice 10');
  nice (10);
  writeln ('New Priority = ',getpriority (prio_process,getpid));
end.


11.3.85 Octal

Declaration
Function Octal(l:longint):longint;
Description
Octal will convert a number specified as an octal number to it's decimal value.

This is useful for the Chmod call, where permissions are specified as octal numbers.

Errors
No checking is performed whether the given number is a correct Octal number. e.g. specifying 998 is possible; the result will be wrong in that case.
See also
Chmod.

Example
Program Example68;

{ Program to demonstrate the Octal function. }

Uses linux;

begin
  Writeln('Mode 777 : ', Octal(777));
  Writeln('Mode 644 : ', Octal(644));
  Writeln('Mode 755 : ', Octal(755));
end.


11.3.86 OpenDir

Declaration
Function OpenDir (f:pchar) : pdir; Function OpenDir (f:string) : pdir;
Description
OpenDir opens the directory f, and returns a pdir pointer to a Dir record, which can be used to read the directory structure. If the directory cannot be opened, nil is returned.
Errors
Errors are returned in LinuxError.
See also
CloseDir, ReadDir, SeekDir, TellDir, opendir (3)

Example
Program Example35;

{ Program to demonstrate the 
  OpenDir,ReadDir, SeekDir and TellDir functions. }

Uses linux;

Var TheDir : PDir;
    ADirent : PDirent;
    Entry : Longint;

begin
  TheDir:=OpenDir('./.');
  Repeat 
    Entry:=TellDir(TheDir);
    ADirent:=ReadDir (TheDir);
    If ADirent<>Nil then
      With ADirent^ do
        begin
        Writeln ('Entry No : ',Entry);
        Writeln ('Inode    : ',ino);
        Writeln ('Offset   : ',off);
        Writeln ('Reclen   : ',reclen);
        Writeln ('Name     : ',pchar(@name[0]));
        end;
  Until ADirent=Nil;
  Repeat
    Write ('Entry No. you would like to see again (-1 to stop): ');
    ReadLn (Entry);
    If Entry<>-1 then 
      begin
      SeekDir (TheDir,Entry);
      ADirent:=ReadDir (TheDir);
      If ADirent<>Nil then
        With ADirent^ do
          begin
          Writeln ('Entry No : ',Entry);
          Writeln ('Inode    : ',ino);
          Writeln ('Offset   : ',off);
          Writeln ('Reclen   : ',reclen);
          Writeln ('Name     : ',pchar(@name[0]));
          end;
    end;
  Until Entry=-1;
  CloseDir (TheDir);
end.


11.3.87 pause

Declaration
Procedure Pause;
Description
Pause puts the process to sleep and waits until the application receives a signal. If a signal handler is installed for the received sigal, the handler will be called and after that pause will return control to the process.
Errors
None.

For an example, see Alarm.


11.3.88 PClose

Declaration
Function PClose (Var F : FileType) : longint;
Description
PClose closes a file opened with POpen. It waits for the command to complete, and then returns the exit status of the command.

Errors
LinuxError is used to report errors. If it is different from zero, the exit status is not valid.
See also
POpen
For an example, see POpen


11.3.89 POpen

Declaration
Procedure POpen (Var F : FileType; Cmd : pathstr; rw : char);
Description
Popen runs the command specified in Cmd, and redirects the standard in or output of the command to the other end of the pipe F. The parameter rw indicates the direction of the pipe. If it is set to 'W', then F can be used to write data, which will then be read by the command from stdinput. If it is set to 'R', then the standard output of the command can be read from F. F should be reset or rewritten prior to using it. F can be of type Text or File. A file opened with POpen can be closed with Close, but also with PClose. The result is the same, but PClose returns the exit status of the command Cmd.
Errors
Errors are reported in LinuxError and are essentially those of the Execve, Dup and AssignPipe commands.

See also
AssignPipe, popen (3) , PClose

Example
Program Example37;

{ Program to demonstrate the Popen function. }

uses linux;

var f : text;
    i : longint;
    
begin
  writeln ('Creating a shell script to which echoes its arguments');
  writeln ('and input back to stdout');
  assign (f,'test21a');
  rewrite (f);
  writeln (f,'#!/bin/sh');
  writeln (f,'echo this is the child speaking.... ');
  writeln (f,'echo got arguments \*"$*"\*');
  writeln (f,'cat');
  writeln (f,'exit 2');
  writeln (f);
  close (f);
  chmod ('test21a',octal (755));
  popen (f,'./test21a arg1 arg2','W');
  if linuxerror<>0 then 
     writeln ('error from POpen : Linuxerror : ', Linuxerror);
  for i:=1 to 10 do 
    writeln (f,'This is written to the pipe, and should appear on stdout.');
  Flush(f);
  Writeln ('The script exited with status : ',PClose (f));
  writeln;
  writeln ('Press <return> to remove shell script.');
  readln;
  assign (f,'test21a');
  erase (f)
end.


11.3.90 ReadDir

Declaration
Function ReadDir (p:pdir) : pdirent;
Description
ReadDir reads the next entry in the directory pointed to by p. It returns a pdirent pointer to a structure describing the entry. If the next entry can't be read, Nil is returned.

Errors
Errors are returned in LinuxError.
See also
CloseDir, OpenDir, SeekDir, TellDir, readdir (3)

For an example, see OpenDir.


11.3.91 ReadLink

Declaration
Function ReadLink(name,linkname:pchar;maxlen:longint):longint; Function ReadLink(name:pathstr):pathstr;
Description
ReadLink returns the file the symbolic link name is pointing to. The first form of this function accepts a buffer linkname of length maxlen where the filename will be stored. It returns the actual number of characters stored in the buffer.

The second form of the function returns simply the name of the file.

Errors
On error, the first form of the function returns -1; the second one returns an empty string. LinuxError is set to report errors:
SYS_ENOTDIR
A part of the path in Name is not a directory.
SYS_EINVAL
maxlen is not positive, or the file is not a symbolic link.
SYS_ENAMETOOLONG
A pathname, or a component of a pathname, was too long.
SYS_ENOENT
the link name does not exist.
SYS_EACCES
No permission to search a directory in the path
SYS_ELOOP
Too many symbolic links were encountered in trans­ lating the pathname.
SYS_EIO
An I/O error occurred while reading from the file system.
SYS_EFAULT
The buffer is not part of the the process's memory space.
SYS_ENOMEM
Not enough kernel memory was available.
See also
SymLink

Example
Program Example62;

{ Program to demonstrate the ReadLink function. }

Uses linux;

Var F : Text;
    S : String;
    
begin
  Assign (F,'test.txt');
  Rewrite (F);
  Writeln (F,'This is written to test.txt');
  Close(f);
  { new.txt and test.txt are now the same file }
  if not SymLink ('test.txt','new.txt') then
    writeln ('Error when symlinking !');
  S:=ReadLink('new.txt');
  If S='' then 
    Writeln ('Error reading link !')
  Else   
    Writeln ('Link points to : ',S);
 { Now remove links }
 If not Unlink ('new.txt') then
   Writeln ('Error when unlinking !');
 If not Unlink ('test.txt') then
   Writeln ('Error when unlinking !');
end.


11.3.92 ReadPort

Declaration
Procedure ReadPort (Port : Longint; Var Value : Byte); Procedure ReadPort (Port : Longint; Var Value : Word); Procedure ReadPort (Port : Longint; Var Value : Longint);
Description
ReadPort reads one Byte, Word or Longint from port Port into Value.

Note that you need permission to read a port. This permission can be set by the root user with the IOperm call.

Errors
In case of an error (not enough permissions read this port), runtime 216 (Access Violation) will occur.
See also

IOperm, ReadPortB, ReadPortW, ReadPortL,WritePort, WritePortB, WritePortL, WritePortW


11.3.93 ReadPortB

Declaration
Procedure ReadPortB (Port : Longint; Var Buf; Count: longint); Function ReadPortB (Port : Longint): Byte;
Description
The procedural form of ReadPortB reads Count bytes from port Port and stores them in Buf. There must be enough memory allocated at Buf to store Count bytes.

The functional form of ReadPortB reads 1 byte from port B and returns the byte that was read.

Note that you need permission to read a port. This permission can be set by the root user with the IOperm call.

Errors
In case of an error (not enough permissions read this port), runtime 216 (Access Violation) will occur.

See also
IOperm, ReadPort, ReadPortW, ReadPortL,WritePort, WritePortB, WritePortL, WritePortW


11.3.94 ReadPortL

Declaration
function ReadPortL (Port : Longint): LongInt; Procedure ReadPortL (Port : Longint; Var Buf; Count: longint);
Description
The procedural form of ReadPortL reads Count longints from port Port and stores them in Buf. There must be enough memory allocated at Buf to store Count Longints.

The functional form of ReadPortB reads 1 longint from port B and returns the longint that was read.

Note that you need permission to read a port. This permission can be set by the root user with the IOperm call.

Errors
In case of an error (not enough permissions read this port), runtime 216 (Access Violation) will occur.
See also
IOperm, ReadPort, ReadPortW, ReadPortB,WritePort, WritePortB, WritePortL, WritePortW


11.3.95 ReadPortW

Declaration
Procedure ReadPortW (Port : Longint; Var Buf; Count: longint); function ReadPortW (Port : Longint): Word;
Description
The procedural form of ReadPortB reads Count words from port Port and stores them in Buf. There must be enough memory allocated at Buf to store Count words.

The functional form of ReadPortB reads 1 word from port B and returns the word that was read.

Note that you need permission to read a port. This permission can be set by the root user with the IOperm call.

Errors
In case of an error (not enough permissions read this port), runtime 216 (Access Violation) will occur.
See also
IOperm, ReadPort, ReadPortB, ReadPortL,WritePort, WritePortB, WritePortL, WritePortW


11.3.96 ReadTimezoneFile

Declaration
procedure ReadTimezoneFile(fn:string);
Description
ReadTimeZoneFile reads the timezone file fn and initializes the local time routines based on the information found there.

There should be no need to call this function. The initialization routines of the linux unit call this routine at unit startup.

Errors
None.
See also
GetTimezoneFile, GetLocalTimezone


11.3.97 SeekDir

Declaration
Procedure SeekDir (p:pdir;off:longint);
Description
SeekDir sets the directory pointer to the off-th entry in the directory structure pointed to by p.
Errors
Errors are returned in LinuxError.
See also
CloseDir, ReadDir, OpenDir, TellDir, seekdir (3)
For an example, see OpenDir.


11.3.98 Select

Declaration
Function Select (N : Longint;
var readfds,writefds,exceptfds : PFDset; Var Timeout) : Longint;
Description
Select checks one of the file descriptors in the FDSets to see if its status changed. readfds, writefds and exceptfds are pointers to arrays of 256 bits. If you want a file descriptor to be checked, you set the corresponding element in the array to 1. The other elements in the array must be set to zero. Three arrays are passed : The entries in readfds are checked to see if characters become available for reading. The entries in writefds are checked to see if it is OK to write to them, while entries in exceptfds are cheked to see if an exception occorred on them. You can use the functions FD_ZERO, FD_Clr, FD_Set, FD_IsSet to manipulate the individual elements of a set. The pointers can be nil. N is the largest index of a nonzero entry plus 1. (= the largest file-descriptor + 1). TimeOut can be used to set a time limit. If TimeOut can be two types :
  1. TimeOut is of type PTime and contains a zero time, the call returns immediately. If TimeOut is Nil, the kernel will wait forever, or until a status changed.
  2. TimeOut is of type Longint. If it is -1, this has the same effect as a Timeout of type PTime which is Nil. Otherwise, TimeOut contains a time in milliseconds.

When the TimeOut is reached, or one of the file descriptors has changed, the Select call returns. On return, it will have modified the entries in the array which have actually changed, and it returns the number of entries that have been changed. If the timout was reached, and no decsriptor changed, zero is returned; The arrays of indexes are undefined after that. On error, -1 is returned.

Errors
On error, the function returns -1, and Errors are reported in LinuxError :
SYS_EBADF
An invalid descriptot was specified in one of the sets.
SYS_EINTR
A non blocked signal was caught.
SYS_EINVAL
N is negative or too big.
SYS_ENOMEM
Select was unable to allocate memory for its internal tables.
See also
SelectText, GetFS, FD_ZERO, FD_Clr, FD_Set, FD_IsSet

Example
Program Example33;

{ Program to demonstrate the Select function. }

Uses linux;

Var FDS : FDSet;

begin
  FD_Zero (FDS);
  FD_Set (0,FDS);
  Writeln ('Press the <ENTER> to continue the program.');
  { Wait until File descriptor 0 (=Input) changes }
  Select (1,@FDS,nil,nil,nil);
  { Get rid of <ENTER> in buffer }
  readln;
  Writeln ('Press <ENTER> key in less than 2 seconds...');
  FD_Zero (FDS);
  FD_Set (0,FDS);
  if Select (1,@FDS,nil,nil,2000)>0 then 
    Writeln ('Thank you !')
    { FD_ISSET(0,FDS) would be true here. }
  else
    Writeln ('Too late !');
end.


11.3.99 SelectText

Declaration
Function SelectText ( var T : Text; TimeOut :PTime) : Longint;
Description
SelectText executes the Select call on a file of type Text. You can specify a timeout in TimeOut. The SelectText call determines itself whether it should check for read or write, depending on how the file was opened : With Reset it is checked for reading, with Rewrite and Append it is checked for writing.
Errors
See Select. SYS_EBADF can also mean that the file wasn't opened.
See also
Select, GetFS


11.3.100 SetPriority

Declaration
Function SetPriority (Which,Who,Prio : Integer) : Integer;
Description
SetPriority sets the priority with which a process is running. Which process(es) is determined by the Which and Who variables. Which can be one of the pre-defined Prio_Process, Prio_PGrp, Prio_User, in which case Who is the process ID, Process group ID or User ID, respectively. Prio is a value in the range -20 to 20.

Errors

Error checking must be done on LinuxError, since a priority can be negative.

sys_esrch
No process found using which and who.
sys_einval
Which was not one of Prio_Process, Prio_Grp or Prio_User.
sys_eperm
A process was found, but neither its effective or real user ID match the effective user ID of the caller.
sys_eacces
A non-superuser tried to a priority increase.

See also
GetPriority, Nice, Setpriority (2)
For an example, see Nice.


11.3.101 Shell

Declaration
Function Shell (Command : String) : Longint;
Description
Shell invokes the bash shell (/bin/sh), and feeds it the command Command (using the -c option). The function then waits for the command to complete, and then returns the exit status of the command, or 127 if it could not complete the Fork or Execve calls.

Errors
Errors are reported in LinuxError.
See also
POpen, Fork, Execve, system (3)

Example
program example56;

uses linux;

{ Program to demonstrate the Shell function }

Var S : Longint;

begin
  Writeln ('Output of ls -l *.pp');
  S:=Shell ('ls -l *.pp');
  Writeln ('Command exited wwith status : ',S);
end.


11.3.102 SigAction

Declaration
Procedure SigAction (Signum : Integer; Var Act,OldAct : PSigActionRec);
Description
Changes the action to take upon receipt of a signal. Act and Oldact are pointers to a SigActionRec record. SigNum specifies the signal, and can be any signal except SIGKILL or SIGSTOP. If Act is non-nil, then the new action for signal SigNum is taken from it. If OldAct is non-nil, the old action is stored there. Sa_Handler may be SIG_DFL for the default action or SIG_IGN to ignore the signal. Sa_Mask Specifies which signals should be ignord during the execution of the signal handler. Sa_Flags Speciefies a series of flags which modify the behaviour of the signal handler. You can 'or' none or more of the following :
SA_NOCLDSTOP
If signum is SIGCHLD do not receive notification when child processes stop.
SA_ONESHOT or SA_RESETHAND
Restore the signal action to the default state once the signal handler has been called.
SA_RESTART
For compatibility with BSD signals.
SA_NOMASK or SA_NODEFER
Do not prevent the signal from being received from within its own signal handler.

Errors
LinuxError is used to report errors.
sys_einval
an invalid signal was specified, or it was SIGKILL or SIGSTOP.
sys_efault
Act,OldAct point outside this process address space
sys_eintr
System call was interrupted.

See also

SigProcMask, SigPending, SigSuspend, Kill, Sigaction (2)

Example
Program example57;

{ Program to demonstrate the SigAction function.}

{ 
do a kill -USR1 pid from another terminal to see what happens.
replace pid with the real pid of this program. 
You can get this pid by running 'ps'.
}

uses Linux;

Var
   oa,na : PSigActionRec;
   
Procedure DoSig(sig : Longint);cdecl;

begin
   writeln('Receiving signal: ',sig);
end; 

begin
   new(na);
   new(oa);
   na^.Handler.sh:=@DoSig;
   na^.Sa_Mask:=0;
   na^.Sa_Flags:=0;
   na^.Sa_Restorer:=Nil;
   SigAction(SigUsr1,na,oa);
   if LinuxError<>0 then
     begin
     writeln('Error: ',linuxerror,'.');
     halt(1);
     end;
   Writeln ('Send USR1 signal or press <ENTER> to exit'); 
   readln;
end.


11.3.103 SigPending

Declaration
Function SigPending : SigSet;
Description
Sigpending allows the examination of pending signals (which have been raised while blocked.) The signal mask of pending signals is returned.

Errors
None
See also
SigAction, SigProcMask, SigSuspend, Signal, Kill, Sigpending (2)


11.3.104 SigProcMask

Declaration
Procedure SigProcMask (How : Integer; SSet,OldSSet : PSigSet);
Description
Changes the list of currently blocked signals. The behaviour of the call depends on How :
SIG_BLOCK
The set of blocked signals is the union of the current set and the SSet argument.
SIG_UNBLOCK
The signals in SSet are removed from the set of currently blocked signals.
SIG_SETMASK
The list of blocked signals is set so SSet.
If OldSSet is non-nil, then the old set is stored in it.

Errors
LinuxError is used to report errors.
sys_efault
SSet or OldSSet point to an adress outside the range of the process.
sys_eintr
System call was interrupted.

See also
SigAction, SigPending, SigSuspend, Kill, Sigprocmask (2)


11.3.105 SigRaise

Declaration
Procedure SigRaise(Sig:integer);
Description
SigRaise sends a Sig signal to the current process.
Errors
None.
See also
Kill, GetPid

Example
Program example64;

{ Program to demonstrate the SigRaise function.}

uses Linux;

Var
   oa,na : PSigActionRec;
   
Procedure DoSig(sig : Longint);cdecl;

begin
   writeln('Receiving signal: ',sig);
end; 

begin
   new(na);
   new(oa);
   na^.handler.sh:=@DoSig;
   na^.Sa_Mask:=0;
   na^.Sa_Flags:=0;
   na^.Sa_Restorer:=Nil;
   SigAction(SigUsr1,na,oa);
   if LinuxError<>0 then
     begin
     writeln('Error: ',linuxerror,'.');
     halt(1);
     end;
   Writeln('Sending USR1 (',sigusr1,') signal to self.');
   SigRaise(sigusr1);
end.


11.3.106 SigSuspend

Declaration
Procedure SigSuspend (Mask : SigSet);
Description
SigSuspend temporarily replaces the signal mask for the process with the one given in Mask, and then suspends the process until a signal is received.

Errors
None
See also
SigAction, SigProcMask, SigPending, Signal, Kill, SigSuspend (2)


11.3.107 Signal

Declaration
Function Signal (SigNum : Integer; Handler : SignalHandler) : SignalHandler;
Description
Signal installs a new signal handler for signal SigNum. This call has the same functionality as the SigAction call. The return value for Signal is the old signal handler, or nil on error.

Errors
LinuxError is used to report errors :
SIG_ERR
An error occurred.

See also
SigAction,Kill, Signal (2)

Example
Program example58;

{ Program to demonstrate the Signal function.}

{ 
do a kill -USR1 pid from another terminal to see what happens.
replace pid with the real pid of this program. 
You can get this pid by running 'ps'.
}

uses Linux;

Procedure DoSig(sig : Longint);cdecl;

begin
   writeln('Receiving signal: ',sig);
end; 

begin
   SigNal(SigUsr1,@DoSig);
   if LinuxError<>0 then
     begin
     writeln('Error: ',linuxerror,'.');
     halt(1);
     end;
   Writeln ('Send USR1 signal or press <ENTER> to exit'); 
   readln;
end.


11.3.108 StringToPPchar

Declaration
Function StringToPPChar(Var S:STring):ppchar;
Description
StringToPPChar splits the string S in words, replacing any whitespace with zero characters. It returns a pointer to an array of pchars that point to the first letters of the words in S. This array is terminated by a Nil pointer.

The function does not add a zero character to the end of the string unless it ends on whitespace.

The function reserves memory on the heap to store the array of PChar; The caller is responsible for freeing this memory.

This function can be called to create arguments for the various Exec calls.

Errors
None.
See also
CreateShellArgV, Execve, Execv

Example
Program Example70;

{ Program to demonstrate the StringToPPchar function. }

Uses linux;

Var S : String;
    P : PPChar;
    I : longint;
    
begin
  // remark whitespace at end.
  S:='This is a string with words. ';
  P:=StringToPPChar(S);
  I:=0;
  While P[i]<>Nil do
    begin
    Writeln('Word ',i,' : ',P[i]);
    Inc(I);
    end;
  FreeMem(P,i*SizeOf(Pchar));  
end.


11.3.109 SymLink

Declaration
Function SymLink (OldPath,NewPath : pathstr) : Boolean;
Description
SymLink makes Newpath point to the file in OldPath, which doesn't necessarily exist. The two files DO NOT have the same inode number. This is known as a 'soft' link. The permissions of the link are irrelevant, as they are not used when following the link. Ownership of the file is only checked in case of removal or renaming of the link. The function returns True if the call was succesfull, False if the call failed.

Errors
Errors are returned in LinuxError.
sys_eperm
The filesystem containing oldpath and newpath doesn't support linking files.
sys_eaccess
Write access for the directory containing Newpath is disallowed, or one of the directories in OldPath or NewPath has no search (=execute) permission.
sys_enoent
A directory entry in OldPath or NewPath does not exist or is a symbolic link pointing to a non-existent directory.
sys_enotdir
A directory entry in OldPath or NewPath is nor a directory.
sys_enomem
Insufficient kernel memory.
sys_erofs
The files are on a read-only filesystem.
sys_eexist
NewPath already exists.
sys_eloop
OldPath or NewPath has a reference to a circular symbolic link, i.e. a symbolic link, whose expansion points to itself.
sys_enospc
The device containing NewPath has no room for anothe entry.
See also
Link, UnLink, ReadLink, Symlink (2)

Example
Program Example22;

{ Program to demonstrate the SymLink and UnLink functions. }

Uses linux;

Var F : Text;
    S : String;
    
begin
  Assign (F,'test.txt');
  Rewrite (F);
  Writeln (F,'This is written to test.txt');
  Close(f);
  { new.txt and test.txt are now the same file }
  if not SymLink ('test.txt','new.txt') then
    writeln ('Error when symlinking !');
  { Removing test.txt still leaves new.txt
    Pointing now to a non-existent file ! }
  If not Unlink ('test.txt') then
    Writeln ('Error when unlinking !');
  Assign (f,'new.txt');
  { This should fail, since the symbolic link
    points to a non-existent file! }
  {$i-}
  Reset (F);
  {$i+}
  If IOResult=0 then
    Writeln ('This shouldn''t happen'); 
 { Now remove new.txt also }
 If not Unlink ('new.txt') then
   Writeln ('Error when unlinking !');
end.


11.3.110 SysInfo

Declaration
Function SysInfo(var Info:TSysinfo):Boolean;
Description
SysInfo returns system information in Info. Returned information in Info includes:
uptime
Number of seconds since boot.
loads
1, 5 and 15 minute load averages.
totalram
total amount of main memory.
freeram
amount of free memory.
sharedram
amount of shared memory
bufferram
amount of memory used by buffers.
totalswap
total amount of swapspace.
freeswap
amount of free swapspace.
procs
number of current processes.
Errors
None.
See also
Uname

Example
program Example64;

{ Example to demonstrate the SysInfo function }

Uses Linux;

Function Mb(L : Longint) : longint;

begin
  Mb:=L div (1024*1024);
end;
   
Var Info : TSysInfo;
    D,M,Secs,H : longint;

begin
  If Not SysInfo(Info) then 
    Halt(1);
  With Info do
    begin
    D:=Uptime div (3600*24);
    UpTime:=UpTime mod (3600*24);
    h:=uptime div 3600;
    uptime:=uptime mod 3600;
    m:=uptime div 60;
    secs:=uptime mod 60;
    Writeln('Uptime : ',d,'days, ',h,' hours, ',m,' min, ',secs,' s.');
    Writeln('Loads  : ',Loads[1],'/',Loads[2],'/',Loads[3]);
    Writeln('Total Ram  : ',Mb(totalram),'Mb.');
    Writeln('Free Ram   : ',Mb(freeram),'Mb.');
    Writeln('Shared Ram : ',Mb(sharedram),'Mb.');
    Writeln('Buffer Ram : ',Mb(bufferram),'Mb.');
    Writeln('Total Swap : ',Mb(totalswap),'Mb.');
    Writeln('Free Swap  : ',Mb(freeswap),'Mb.');
    end;
end.


11.3.111 TCDrain

Declaration
Function TCDrain (Fd:longint) : Boolean;
Description
TCDrain waits until all data to file descriptor Fd is transmitted.

The function returns True if the call was succesfull, False otherwise.

Errors
Errors are reported in LinuxError
See also
termios (2)


11.3.112 TCFlow

Declaration
Function TCFlow (Fd,Act:longint) : Boolean;
Description
TCFlow suspends/resumes transmission or reception of data to or from the file descriptor Fd, depending on the action Act. This can be one of the following pre-defined values:
TCOOFF
suspend reception/transmission,
TCOON
resume reception/transmission,
TCIOFF
transmit a stop character to stop input from the terminal,
TCION
transmit start to resume input from the terminal.
The function returns True if the call was succesfull, False otherwise.

Errors
Errors are reported in LinuxError.
See also
termios (2)


11.3.113 TCFlush

Declaration
Function TCFlush (Fd,QSel:longint) : Boolean;
Description
TCFlush discards all data sent or received to/from file descriptor fd. QSel indicates which queue should be discard. It can be one of the following pre-defined values :
TCIFLUSH
input,
TCOFLUSH
output,
TCIOFLUSH
both input and output.
The function returns True if the call was succesfull, False otherwise.

Errors
Errors are reported in LinuxError.
See also
termios (2)


11.3.114 TCGetAttr

Declaration
Function TCGetAttr (fd:longint;var tios:TermIOS) : Boolean;
Description
TCGetAttr gets the terminal parameters from the terminal referred to by the file descriptor fd and returns them in a TermIOS structure tios. The function returns True if the call was succesfull, False otherwise.

Errors
Errors are reported in LinuxError
See also
TCSetAttr, termios (2)

Example
Program Example55;

uses Linux;

{ Program to demonstrate the TCGetAttr/TCSetAttr/CFMakeRaw functions. }

procedure ShowTermios(var tios:Termios);
begin
  WriteLn('Input Flags  : $',hexstr(tios.c_iflag,8)+#13);
  WriteLn('Output Flags : $',hexstr(tios.c_oflag,8));
  WriteLn('Line Flags   : $',hexstr(tios.c_lflag,8));
  WriteLn('Control Flags: $',hexstr(tios.c_cflag,8));
end;

var
  oldios,
  tios : Termios;
begin
  WriteLn('Old attributes:');
  TCGetAttr(1,tios);
  ShowTermios(tios);
  oldios:=tios;
  Writeln('Setting raw terminal mode');  
  CFMakeRaw(tios);
  TCSetAttr(1,TCSANOW,tios);
  WriteLn('Current attributes:');
  TCGetAttr(1,tios);
  ShowTermios(tios);
  TCSetAttr(1,TCSANOW,oldios);
end.


11.3.115 TCGetPGrp

Declaration
Function TCGetPGrp (Fd:longint;var Id:longint) : boolean;
Description
TCGetPGrp returns the process group ID of a foreground process group in Id The function returns True if the call was succesfull, False otherwise

Errors
Errors are reported in LinuxError
See also
termios (2)


11.3.116 TCSendBreak

Declaration
Function TCSendBreak (Fd,Duration:longint) : Boolean;
Description
TCSendBreak Sends zero-valued bits on an asynchrone serial connection decsribed by file-descriptor Fd, for duration Duration. The function returns True if the action was performed successfully, False otherwise.

Errors
Errors are reported in LinuxError.
See also
termios (2)


11.3.117 TCSetAttr

Declaration
Function TCSetAttr (Fd:longint;OptAct:longint;var Tios:TermIOS) : Boolean;
Description
TCSetAttr Sets the terminal parameters you specify in a TermIOS structure Tios for the terminal referred to by the file descriptor Fd. OptAct specifies an optional action when the set need to be done, this could be one of the following pre-defined values:
TCSANOW
set immediately.
TCSADRAIN
wait for output.
TCSAFLUSH
wait for output and discard all input not yet read.
The function Returns True if the call was succesfull, False otherwise.

Errors
Errors are reported in LinuxError.
See also
TCGetAttr, termios (2)
For an example, see TCGetAttr.


11.3.118 TCSetPGrp

Declaration
Function TCSetPGrp (Fd,Id:longint) : boolean;
Description
TCSetPGrp Sets the Process Group Id to Id. The function returns True if the call was successful, False otherwise.

Errors
Errors are returned in LinuxError.
See also
TCGetPGrp, termios (2)
For an example, see TCGetPGrp.


11.3.119 TTYName

Declaration
Function TTYName (var f) : String;
Description
Returns the name of the terminal pointed to by f. f must be a terminal. f can be of type:
  1. longint for file handles;
  2. Text for text variables such as input etc.

Errors
Returns an empty string in case of an error. Linuxerror may be set to indicate what error occurred, but this is uncertain.
See also
IsATTY,IOCtl


11.3.120 TellDir

Declaration
Function TellDir (p:pdir) : longint;
Description
TellDir returns the current location in the directory structure pointed to by p. It returns -1 on failure.
Errors
Errors are returned in LinuxError.
See also
CloseDir, ReadDir, SeekDir, OpenDir, telldir (3)
For an example, see OpenDir.


11.3.121 Umask

Declaration
Function Umask (Mask : Integer) : Integer;
Description
Change the file creation mask for the current user to Mask. The current mask is returned.

Errors
None
See also
Chmod, Umask (2)

Example
Program Example27;

{ Program to demonstrate the Umask function. }

Uses linux;

begin
  Writeln ('Old Umask was : ',Umask(Octal(111)));
  WRiteln ('New Umask is  : ',Octal(111));
end.


11.3.122 Uname

Declaration
Procedure Uname (var unamerec:utsname);
Description
Uname gets the name and configuration of the current LINUX kernel, and returns it in unamerec.

Errors
LinuxError is used to report errors.
See also
GetHostName, GetDomainName, uname (2)


11.3.123 UnLink

Declaration
Function UnLink (Var Path) : Boolean;
Description
UnLink decreases the link count on file Path. Path can be of type PathStr or PChar. If the link count is zero, the file is removed from the disk. The function returns True if the call was succesfull, False if the call failed.

Errors
Errors are returned in LinuxError.
sys_eaccess
You have no write access right in the directory containing Path, or you have no search permission in one of the directory components of Path.
sys_eperm
The directory containing pathname has the sticky-bit set and the process's effective uid is neither the uid of the file to be deleted nor that of the directory containing it.
sys_enoent
A component of the path doesn't exist.
sys_enotdir
A directory component of the path is not a directory.
sys_eisdir
Path refers to a directory.
sys_enomem
Insufficient kernel memory.
sys_erofs
Path is on a read-only filesystem.

See also
Link, SymLink, Unlink (2)
For an example, see Link.


11.3.124 Utime

Declaration
Function Utime (path : pathstr; utim : utimbuf) : Boolean;
Description
Utime sets the access and modification times of a file. the utimbuf record contains 2 fields, actime, and modtime, both of type Longint. They should be filled with an epoch-like time, specifying, respectively, the last access time, and the last modification time. For some filesystem (most notably, FAT), these times are the same.

Errors
Errors are returned in LinuxError.
sys_eaccess
One of the directories in Path has no search (=execute) permission.
sys_enoent
A directory entry in Path does not exist or is a symbolic link pointing to a non-existent directory.
Other errors may occur, but aren't documented.

See also
GetEpochTime, Chown, Access, utime (() 2)

Example
Program Example25;

{ Program to demonstrate the UTime function. }

Uses linux;

Var utim : utimbuf;
    year,month,day,hour,minute,second : Word;
       
begin
  { Set access and modification time of executable source }
  GetTime (hour,minute,second);
  GetDate (year,month,day);  
  utim.actime:=LocalToEpoch(year,month,day,hour,minute,second);
  utim.modtime:=utim.actime;
  if not Utime('ex25.pp',utim) then
    writeln ('Call to UTime failed !')
  else
    begin
    Write ('Set access and modification times to : ');
    Write (Hour:2,':',minute:2,':',second,', ');
    Writeln (Day:2,'/',month:2,'/',year:4);
    end;
end.


11.3.125 WaitPid

Declaration
Function WaitPid (Pid : longint; Status : pointer; Options : Longint) : Longint;
Description
WaitPid waits for a child process with process ID Pid to exit. The value of Pid can be one of the following:
Pid < -1
Causes WaitPid to wait for any child process whose process group ID equals the absolute value of pid.
Pid = -1
Causes WaitPid to wait for any child process.
Pid = 0
Causes WaitPid to wait for any child process whose process group ID equals the one of the calling process.
Pid > 0
Causes WaitPid to wait for the child whose process ID equals the value of Pid.
The Options parameter can be used to specify further how WaitPid behaves:
WNOHANG
Causes Waitpid to return immediately if no child has exited.
WUNTRACED
Causes WaitPid to return also for children which are stopped, but whose status has not yet been reported.
__WCLONE
Causes WaitPid also to wait for threads created by the Clone call.
Upon return, it returns the exit status of the process, or -1 in case of failure.

Errors
Errors are returned in LinuxError.
See also
Fork, Execve, waitpid (2)

For an example, see Fork.


11.3.126 WritePort

Declaration
Procedure WritePort (Port : Longint; Value : Byte); Procedure WritePort (Port : Longint; Value : Word); Procedure WritePort (Port : Longint; Value : Longint);
Description
WritePort writes Value - 1 byte, Word or longint - to port Port.

Note: You need permission to write to a port. This permission can be set with root permission with the IOperm call.

Errors
In case of an error (not enough permissions to write to this port), runtime 216 (Access Violation) will occur.
See also
IOperm, WritePortB, WritePortL, WritePortW, ReadPortB, ReadPortL, ReadPortW


11.3.127 WritePortB

Declaration
Procedure WritePortB (Port : Longint; Value : Byte); Procedure WritePortB (Port : Longint; Var Buf; Count: longint);
Description
The first form of WritePortB writes 1 byte to port Port. The second form writes Count bytes from Buf to port Port.

Note: You need permission to write to a port. This permission can be set with root permission with the IOperm call.

Errors
In case of an error (not enough permissions to write to this port), runtime 216 (Access Violation) will occur.
See also
IOperm, WritePort, WritePortL, WritePortW, ReadPortB, ReadPortL, ReadPortW


11.3.128 WritePortL

Declaration
Procedure WritePortL (Port : Longint; Value : Longint); Procedure WritePortL (Port : Longint; Var Buf; Count: longint);
Description
The first form of WritePortB writes 1 byte to port Port. The second form writes Count bytes from Buf to port Port.

Note: You need permission to write to a port. This permission can be set with root permission with the IOperm call.

Errors
In case of an error (not enough permissions to write to this port), runtime 216 (Access Violation) will occur.
See also
IOperm, WritePort, WritePortB, WritePortW, ReadPortB, ReadPortL, ReadPortW


11.3.129 WritePortW

Declaration
Procedure WritePortW (Port : Longint; Var Buf; Count: longint); Procedure WritePortW (Port : Longint; Value : Word);
Description
The first form of WritePortB writes 1 byte to port Port. The second form writes Count bytes from Buf to port Port.

Note: You need permission to write to a port. This permission can be set with root permission with the IOperm call.

Errors
In case of an error (not enough permissions to write to this port), runtime 216 (Access Violation) will occur.
See also
IOperm, WritePort, WritePortL, WritePortB, ReadPortB, ReadPortL, ReadPortW



root
2000-12-20