(libc.info.gz) Terminal Access Functions

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(libc.info.gz) Process Group Functions

(libc.info.gz) Functions for Job Control

 
 27.7.3 Functions for Controlling Terminal Access
 ------------------------------------------------
 
 These are the functions for reading or setting the foreground process
 group of a terminal.  You should include the header files `sys/types.h'
 and `unistd.h' in your application to use these functions.  
 
    Although these functions take a file descriptor argument to specify
 the terminal device, the foreground job is associated with the terminal
 file itself and not a particular open file descriptor.
 
  -- Function: pid_t tcgetpgrp (int FILEDES)
      This function returns the process group ID of the foreground
      process group associated with the terminal open on descriptor
      FILEDES.
 
      If there is no foreground process group, the return value is a
      number greater than `1' that does not match the process group ID
      of any existing process group.  This can happen if all of the
      processes in the job that was formerly the foreground job have
      terminated, and no other job has yet been moved into the
      foreground.
 
      In case of an error, a value of `-1' is returned.  The following
      `errno' error conditions are defined for this function:
 
     `EBADF'
           The FILEDES argument is not a valid file descriptor.
 
     `ENOSYS'
           The system doesn't support job control.
 
     `ENOTTY'
           The terminal file associated with the FILEDES argument isn't
           the controlling terminal of the calling process.
 
  -- Function: int tcsetpgrp (int FILEDES, pid_t PGID)
      This function is used to set a terminal's foreground process group
      ID.  The argument FILEDES is a descriptor which specifies the
      terminal; PGID specifies the process group.  The calling process
      must be a member of the same session as PGID and must have the same
      controlling terminal.
 
      For terminal access purposes, this function is treated as output.
      If it is called from a background process on its controlling
      terminal, normally all processes in the process group are sent a
      `SIGTTOU' signal.  The exception is if the calling process itself
      is ignoring or blocking `SIGTTOU' signals, in which case the
      operation is performed and no signal is sent.
 
      If successful, `tcsetpgrp' returns `0'.  A return value of `-1'
      indicates an error.  The following `errno' error conditions are
      defined for this function:
 
     `EBADF'
           The FILEDES argument is not a valid file descriptor.
 
     `EINVAL'
           The PGID argument is not valid.
 
     `ENOSYS'
           The system doesn't support job control.
 
     `ENOTTY'
           The FILEDES isn't the controlling terminal of the calling
           process.
 
     `EPERM'
           The PGID isn't a process group in the same session as the
           calling process.
 
  -- Function: pid_t tcgetsid (int FILDES)
      This function is used to obtain the process group ID of the session
      for which the terminal specified by FILDES is the controlling
      terminal.  If the call is successful the group ID is returned.
      Otherwise the return value is `(pid_t) -1' and the global variable
      ERRNO is set to the following value:
     `EBADF'
           The FILEDES argument is not a valid file descriptor.
 
     `ENOTTY'
           The calling process does not have a controlling terminal, or
           the file is not the controlling terminal.
 

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(libc.info.gz) Process Group Functions

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