SETEUID(3P) POSIX Programmer's Manual SETEUID(3P)

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.

seteuid — set effective user ID

#include <unistd.h>
int seteuid(uid_t uid);

If uid is equal to the real user ID or the saved set-user-ID, or if the process has appropriate privileges, seteuid() shall set the effective user ID of the calling process to uid; the real user ID and saved set-user-ID shall remain unchanged.

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

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

The seteuid() function shall fail if:
The value of the uid argument is invalid and is not supported by the implementation.
The process does not have appropriate privileges and uid does not match the real user ID or the saved set-user-ID.

The following sections are informative.



Refer to the RATIONALE section in setuid().


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

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

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 at .

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2017 IEEE/The Open Group