euidaccess(3)

✨ euidaccess(3) ✨

okay bestie, welcome to euidaccess(3) — that's a library functions manual page, for the record, and we're about to have a whole moment about it 💖

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🌸 NAME 🌸

euidaccess, eaccess — check the effective user's permissions for a file 🫶

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📚 LIBRARY 📚

Standard C library — that's libc, link it with -lc 💅

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✨ SYNOPSIS ✨

#define _GNU_SOURCE             /* See feature_test_macros(7) */
#include <unistd.h>

int euidaccess(const char *path, int mode);
int eaccess(const char *path, int mode);

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💫 DESCRIPTION 💫

So here's the tea ☕ — euidaccess() is giving very much like access(2): it checks the permissions and the existence of the file that its argument path points at. Same energy. BUT. 👀

Here's where they diverge, and it's the whole plot twist: access(2) does its checks using the real user and group identifiers of the process. euidaccess()? It uses the effective identifiers instead. That's the entire vibe. That's the difference. Periodt. 💅

mode is a mask made up of one or more of R_OK, W_OK, X_OK, and F_OK — and they mean exactly the same things they mean for access(2). No new lore, same meanings 🎀

And eaccess() is just a synonym for euidaccess() — it's there for compatibility with some other systems. It's the same function wearing a little alias hat 👑

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🎯 RETURN VALUE 🎯

• On success — meaning all the requested permissions were granted — you get zero back. slay ✨
• On error — meaning at least one bit in mode asked for a permission that's denied, or some other error happened — you get -1, and errno is set to indicate the error. 😭

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🚨 ERRORS 🚨

As for access(2). That's it. Go read that page, bestie, the errors live there 📖

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🧬 ATTRIBUTES 🧬

For an explanation of the terms used in this section, see attributes(7).

• Interface: euidaccess(), eaccess() — Attribute: Thread safety — Value: MT-Safe 🫶

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🕰️ VERSIONS 🕰️

Some other systems have an eaccess() function. that's the whole thing 💀

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📏 STANDARDS 📏

None. Not a single one. it's giving unstandardized icon behavior 🙈

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📜 HISTORY 📜

• eaccess() — glibc 2.4.

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⚠️ NOTES ⚠️

Warning: using this function to check a process's permissions on a file before performing some operation based on that information leads to race conditions — because the file permissions may change between those two steps. 💀 Generally, it is safer to just attempt the desired operation and handle any permission error that occurs. like, just do the thing and deal with it, fr fr.

Also important: this function always dereferences symbolic links. Always. No negotiation. If you need to check the permissions on a symbolic link itself, use faccessat(2) with the flags AT_EACCESS and AT_SYMLINK_NOFOLLOW. that's the move 🧚

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👀 SEE ALSO 👀

access(2), chmod(2), chown(2), faccessat(2), open(2), setgid(2), setuid(2), stat(2), credentials(7), path_resolution(7)

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okay that's the whole page, you ate that 🍓 this came to you courtesy of Linux man-pages 6.20, dated 2026-02-08 — and yes, that's euidaccess(3), no cap 💜 mwah, go check some permissions bestie 🌈