Name

setsid − POSIX create session and set process group ID

Syntax

#include <sys/types.h>
pid_t
setsid()

Description

The setsid system call creates a new session, if the calling process is not a process group leader. The calling process is the session leader of the new session, the process group leader of the new process group, and does not have a controlling terminal. The process group ID of the calling process is set equal to the process ID of the calling process.

Return Values

Upon successful completion, the setsid system call returns the value of the process group ID of the calling process. If the setsid system call fails, −1 is returned, and the global variable errno indicates the reason. 

Diagnostics

The setsid system call fails and a new session is not created if the following occurs:

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

See Also

getpgrp(2), setpgid(3)