GETEUID(3POSIX)

💖 GETEUID 💖

okay bestie, welcome to the POSIX Programmer's Manual — this page is geteuid(3POSIX) and it's literally the shortest little glow-up in the whole unistd.h friend group. no cap.

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🎀 PROLOG 🎀

real talk before we start: this manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (so like… go consult the corresponding Linux manual page for the deets on Linux behavior, bestie), or the interface may not be implemented on Linux at all. it's giving "portable but check your platform" energy.

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✨ NAME ✨

geteuid — get the effective user ID 💅

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🌸 SYNOPSIS 🌸

#include <unistd.h>

uid_t geteuid(void);

that's it. that's the whole thing. no args, no drama, just vibes 🦋

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💜 DESCRIPTION 💜

The geteuid() function shall return the effective user ID of the calling process.

and the slayest part? The geteuid() function shall not modify errno. it minds its own business. it does not touch your errno. iconic behavior fr fr 🫶

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🔥 RETURN VALUE 🔥

The geteuid() function shall always be successful and no return value is reserved to indicate an error.

no error sentinel. no "oops" value. it just works. main character energy tbh.

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💀 ERRORS 💀

No errors are defined.

The following sections are informative.

yes bestie, the Errors section is empty and that is CORRECT and it is NOT a typo. it cannot fail. periodt.

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🙈 EXAMPLES 🙈

None.

(nothing to demo, she just works 😌)

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🍓 APPLICATION USAGE 🍓

None.

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🧚 RATIONALE 🧚

so in a conforming environment, geteuid() will always succeed. easy.

BUT — and this is the tea ☕ — it is possible for implementations to provide an extension where a process in a non-conforming environment will not be associated with a user or group ID. like, no user, no group, just vibes.

It is recommended that such implementations return (uid_t)-1 and set errno to indicate such an environment. and here's the plot twist: doing so does not violate this standard, since such an environment is already an extension. so they're not breaking the rules, they're just playing a different game 💅

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🌈 FUTURE DIRECTIONS 🌈

None.

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⭐ SEE ALSO ⭐

• getegid()
• getgid()
• getuid()
• setegid()
• seteuid()
• setgid()
• setregid()
• setreuid()
• setuid()

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

go read those next bestie, they're the whole friend group 🫶

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👑 COPYRIGHT 👑

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 http://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, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .

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and that's the whole page!! written by IEEE/The Open Group back in 2017, GETEUID(3POSIX), no cap. ily, go check your effective uid bestie 💖✨🎀🦋