getpgrp(2)
Name
getpgrp − get process group
Syntax
#include <sys/types.h>
#include <unistd.h>
pgrp = getpgrp(pid)
pid_t pgrp;
pid_t pid;
Description
The system call getprgrp returns the process group of the specified process. If pid is zero, the call applies to the current process.
Process groups are used for distribution of signals and by terminals to arbitrate requests for their input. Processes that have the same process group as the terminal are the foreground and may read, while others block with a signal if they attempt to read.
This call is used by programs such as csh() to create process groups in implementing job control. The TIOCGPGRP and TIOCSPGRP calls described in tty() are used to get and set the process group of the control terminal.
Environment
When your program is compiled in the System V or POSIX environment, getpgrp is called without arguments and the process group of the current process is returned.
Additionally, in POSIX mode, getpgrp returns a value type of pid_t.
Diagnostics
The getpgrp call fails under the following condition:
[ESRCH] No such process, PID.