NAME

setsid, setpgrp, setpgrp3 − create session and set process group ID

SYNOPSIS

#include <unistd.h>

pid_t setsid(void);

pid_t setpgrp(void);

pid_t setpgrp3(void);

DESCRIPTION

If the calling process is not a process group leader, setsid() or setpgrp() creates a new session.  The calling process becomes the session leader of this new session, it becomes the process group leader of a new process group, and it has no controlling terminal.  The process group ID of the calling process is set equal to the process ID of the calling process.  The calling process is the only process in the new process group, and the only process in the new session. 

The setpgrp() function is provided for backward compatibility only. 

setpgrp3() function is provided for HPUX compatibity in future releases.  setpgrp3() is functionally equivalent to setpgrp(). 

RETURN VALUE

Upon successful completion, setsid() returns the value of the new process group ID of the calling process.  Otherwise, it returns a value of −1, and sets errno to indicate the error. 

The setpgrp() function returns the value of the process group ID of the calling process. 

ERRORS

If setsid() fails, no changes occur, and errno (see errno(2)) is set to one of the following values:

[EPERM] The calling process is already a process group leader. 

[EPERM] The process group ID of a process other than the calling process matches the process ID of the calling process. 

WARNINGS

The semantics for setpgrp() may change in a future release (see setpgrp3()). 

AUTHOR

setpgrp() and setsid() were developed by HP and AT&T. 

SEE ALSO

exec(2), exit(2), fork(2), getpid(2), kill(2), setpgid(2), signal(2), termio(7). 

STANDARDS CONFORMANCE

setsid(): AES, SVID3, XPG3, XPG4, FIPS 151-2, POSIX.1

setpgrp(): SVID2, SVID3, XPG2

Hewlett-Packard Company  —  HP-UX Release 10.20:  July 1996