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Command Section
TCGETPGRP(3)           FreeBSD Library Functions Manual           TCGETPGRP(3)

NAME
     tcgetpgrp - get foreground process group ID

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/types.h>
     #include <unistd.h>

     pid_t
     tcgetpgrp(int fd);

DESCRIPTION
     The tcgetpgrp() function returns the value of the process group ID of the
     foreground process group associated with the terminal device.  If there
     is no foreground process group, tcgetpgrp() returns an invalid process
     ID.

ERRORS
     If an error occurs, tcgetpgrp() returns -1 and the global variable errno
     is set to indicate the error, as follows:

     [EBADF]            The fd argument is not a valid file descriptor.

     [ENOTTY]           The calling process does not have a controlling
                        terminal or the underlying terminal device represented
                        by fd is not the controlling terminal.

SEE ALSO
     setpgid(2), setsid(2), tcsetpgrp(3)

STANDARDS
     The tcgetpgrp() function is expected to be compliant with the IEEE Std
     1003.1-1988 (``POSIX.1'') specification.

FreeBSD 11.1-RELEASE-p4          June 4, 1993          FreeBSD 11.1-RELEASE-p4
Command Section