NAME

getpid, getpgrp, getppid, getpgid − 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);

DESCRIPTION

getpid returns the process ID of the calling process. 

getpgrp returns the process group ID of the calling process. 

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.