setegid - Man Page

set the effective group ID


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.


#include <unistd.h>

int setegid(gid_t gid);


If gid is equal to the real group ID or the saved set-group-ID, or if the process has appropriate privileges, setegid() shall set the effective group ID of the calling process to gid; the real group ID, saved set-group-ID, and any supplementary group IDs shall remain unchanged.

The setegid() function shall not affect the supplementary group list in any way.

Return Value

Upon successful completion, 0 shall be returned; otherwise, -1 shall be returned and errno set to indicate the error.


The setegid() function shall fail if:


The value of the gid argument is invalid and is not supported by the implementation.


The process does not have appropriate privileges and gid does not match the real group ID or the saved set-group-ID.

The following sections are informative.



Application Usage



Refer to the RATIONALE section in setuid().

Future Directions


See Also

exec, getegid(), geteuid(), getgid(), getuid(), seteuid(), setgid(), setregid(), setreuid(), setuid()

The Base Definitions volume of POSIX.1-2017, <sys_types.h>, <unistd.h>

Referenced By

getegid(3p), geteuid(3p), getgid(3p), getuid(3p), seteuid(3p), setgid(3p), setregid(3p), setreuid(3p), setuid(3p), unistd.h(0p).

2017 IEEE/The Open Group POSIX Programmer's Manual