getpid(2)

NAME
     getpid, getpgrp, getppid, getpgid, BSDgetpgrp - get process, process
     group, and parent process IDs

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

     pid_t getpid(void);

     pid_t getpgrp(void);

     pid_t getppid(void);

     pid_t getpgid(pid_t pid);

     pid_t BSDgetpgrp(pid_t pid);

DESCRIPTION
     getpid returns the process ID of the calling process.

     getpgrp returns the process group ID of the calling process.  The
     BSDgetpgrp form is provided for Berkeley compatiblity.  If the pid_t is
     0, it is the same as the getpgrp form, otherwise it returns the process
     group for the argument, if the process exists.

     getppid returns the parent process ID of the calling process.

     getpgid returns the process group ID of the process whose process ID is
     equal to pid, or the process group ID of the calling process, if pid is
     equal to zero.

     getpgid will fail if one or more of the following is true:

     EPERM          The process whose process ID is equal to pid is not in the
                    same session as the calling process, and the
                    implementation does not allow access to the process group
                    ID of that process from the calling process.

     ESRCH          There is no process with a process ID equal to pid.

SEE ALSO
     exec(2), fork(2), getpid(2), getsid(2), intro(2), setpgid(2), setsid(2)
     setpgrp(2), signal(2).

DIAGNOSTICS
     Upon successful completion, getpgid returns a process group ID.
     Otherwise, a value of (pid_t) -1 is returned and errno is set to indicate
     the error.