setsid() -- create a new session

SYNOPSIS

#include <sys/types.h>

#include <unistd.h>

pid_t setsid(void);

The setsid() function creates a new session, if the calling process is not a process group leader. Upon return the calling process is the session leader of this new session, is the process group leader of a new process group, and 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.

PARAMETERS

None.

RETURN VALUES

If successful, setsid() returns the value of the session ID of the calling process. On failure, it returns a value of -1 and sets errno to one of the following values:

EPERM: The calling process is already a process group leader, or the process group ID of a process that is not the calling process matches the process ID of the calling process.

CONFORMANCE

POSIX.1 (1996)

MULTITHREAD SAFETY LEVEL

Async-signal-safe.

PORTING ISSUES

In Win32, detaching from controlling terminal means the following:

If there are no other processes using the console window (for example, an invoking shell, or a previously-invoked child), the console window is closed.

Any children created after the call to setsid() is created without a console window attached.

The returned process group ID is the Win32 process ID of the process group leader. Refer to Windows Concepts in the MKS Toolkit UNIX to Windows Porting Guide for more information about process IDs.

AVAILABILITY

MKS Toolkit for Professional Developers
MKS Toolkit for Enterprise Developers
MKS Toolkit for Enterprise Developers 64-Bit Edition

setsid()
create a new session

Function