User  |  Syst  |  Libr  |  Device  |  Files  |  Other  |  Admin  |  Head  |

---

   setsid.3p    ( 3 )

---

---

Пролог (Prolog)

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.

---

Имя (Name)

setsid — create session and set process group ID

---

Синопсис (Synopsis)

#include <unistd.h>

       pid_t setsid(void);

---

Описание (Description)

The setsid() 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.

---

Возвращаемое значение (Return value)

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

---

Ошибки (Error)

The setsid() function shall fail if:

       EPERM  The 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.

---

Примеры (Examples)

None.

---

Использование в приложениях (Application usage)

None.

---

Обоснование (Rationale)

The setsid() function is similar to the setpgrp() function of
       System V.  System V, without job control, groups processes into
       process groups and creates new process groups via setpgrp(); 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 via
       setsid().  The setsid() function also creates the initial process
       group contained in the session. Additional process groups can be
       created via the setpgid() 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 with fork()
       and have it call setsid().  The fork() function guarantees that
       the process ID of the new process does not match any existing
       process group ID.

---

Будущие направления (Future directions)

None.

---

Смотри также (See also)

getsid(3p), setpgid(3p), setpgrp(3p)

       The Base Definitions volume of POSIX.1‐2017, sys_types.h(0p),
       unistd.h(0p)

---