NAME
getpid(), getpgid(), getpgrp(), getpgrp2(), getppid() — get process, process group and parent process ID.
SYNOPSIS
#include <unistd.h>
pid_t getpgid (pid_t pid);
pid_t getpgrp(void);
pid_t getpgrp2(pid_t pid);
pid_t getpid(void);
pid_t getppid(void);
DESCRIPTION
These functions return process, process group and parent process IDs,
as follows:
- getpgid()
Process group ID of the specified process.
If
pid
is zero, the call applies to the calling process.
Same result as
getpgrp2().
- getpgrp()
Process group ID of the calling process.
- getpgrp2()
Process group ID of the specified process.
If
pid
is zero, the call applies to the calling process.
Same result as
getpgid().
- getpid()
Process ID of the calling process.
- getppid()
Parent process ID of the calling process.
If the parent process is the initialization process (known as
init),
the call returns 1.
Security Restrictions
The
getpgrp2
system call is subject to
compartmental restrictions.
See
compartments(5)
for more information about compartmentalization on systems that support
that feature.
Compartmental restrictions can be overridden if the process possesses the
COMMALLOWED
privilege (PRIV_COMMALLOWED).
Processes owned by the superuser may not have this privilege.
Processes owned by any user may have this privilege, depending on system
configuration.
See
privileges(5)
for more information about privileged access on
systems that support fine-grained privileges.
RETURN VALUE
The functions return the following values:
- n
Successful completion.
n
is a nonnegative process ID, as described above.
- -1
Failure:
getpgid()
and
getgrp2()
only.
errno
is set to indicate the error.
ERRORS
If
getpgid()
or
getpgrp2()
fails,
errno
is set to one of the following values:
- [EPERM]
The current process and
pid
are not in the same session (see
setsid(2)).
- [ESRCH]
No process can be found corresponding to that specified by
pid.
AUTHOR
getpid(),
getppid(),
getpgrp(),
and
getpgrp2()
were developed by HP, AT&T, and the University of California, Berkeley.
STANDARDS CONFORMANCE
getpid(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1
getpgrp(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1
getppid(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1
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