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setsid(3p) — Linux manual page

PROLOG \|NAME \|SYNOPSIS \|DESCRIPTION \|RETURN VALUE \|ERRORS \|EXAMPLES \|APPLICATION USAGE \|RATIONALE \|FUTURE DIRECTIONS \|SEE ALSO \|COPYRIGHT

SETSID(3P)              POSIX Programmer's ManualSETSID(3P)

PROLOG top

       This manual page is part of the POSIX Programmer's Manual.  The       Linux implementation of this interface may differ (consult the       corresponding Linux manual page for details of Linux behavior), or       the interface may not be implemented on Linux.

NAME top

       setsid — create session and set process group ID

SYNOPSIS top

       #include <unistd.h>       pid_t setsid(void);

DESCRIPTION top

       Thesetsid() function shall create a new session, if the calling       process is not a process group leader. Upon return the calling       process shall be the session leader of this new session, shall be       the process group leader of a new process group, and shall have no       controlling terminal. The process group ID of the calling process       shall be set equal to the process ID of the calling process. The       calling process shall be the only process in the new process group       and the only process in the new session.

RETURN VALUE top

       Upon successful completion,setsid() shall return the value of the       new process group ID of the calling process. Otherwise, it shall       return -1 and seterrno to indicate the error.

ERRORS top

       Thesetsid() function shall fail if:EPERMThe calling process is already a process group leader, or              the process group ID of a process other than the calling              process matches the process ID of the calling process.The following sections are informative.

EXAMPLES top

       None.

APPLICATION USAGE top

       None.

RATIONALE top

       Thesetsid() function is similar to thesetpgrp() function of       System V.  System V, without job control, groups processes into       process groups and creates new process groups viasetpgrp(); only       one process group may be part of a login session.       Job control allows multiple process groups within a login session.       In order to limit job control actions so that they can only affect       processes in the same login session, this volume of POSIX.1‐2017       adds the concept of a session that is created viasetsid().  Thesetsid() function also creates the initial process group contained       in the session. Additional process groups can be created via thesetpgid() function. A System V process group would correspond to a       POSIX System Interfaces session containing a single POSIX process       group. Note that this function requires that the calling process       not be a process group leader. The usual way to ensure this is       true is to create a new process withfork() and have it callsetsid().  Thefork() function guarantees that the process ID of       the new process does not match any existing process group ID.

FUTURE DIRECTIONS top

       None.

COPYRIGHT top

       Portions of this text are reprinted and reproduced in electronic       form from IEEE Std 1003.1-2017, Standard for Information       Technology -- Portable Operating System Interface (POSIX), The       Open Group Base Specifications Issue 7, 2018 Edition, Copyright       (C) 2018 by the Institute of Electrical and Electronics Engineers,       Inc and The Open Group.  In the event of any discrepancy between       this version and the original IEEE and The Open Group Standard,       the original IEEE and The Open Group Standard is the referee       document. The original Standard can be obtained online athttp://www.opengroup.org/unix/online.html .       Any typographical or formatting errors that appear in this page       are most likely to have been introduced during the conversion of       the source files to man page format. To report such errors, seehttps://www.kernel.org/doc/man-pages/reporting_bugs.html .IEEE/The Open Group                2017SETSID(3P)

Pages that refer to this page:unistd.h(0p), _Exit(3p), getpgid(3p), getpgrp(3p), getpid(3p), getppid(3p), getsid(3p), kill(3p), setpgid(3p), setpgrp(3p), tcgetpgrp(3p)