euidaccess(3) Library Functions Manual euidaccess(3)
NAME
euidaccess, eaccess - check effective user's permissions for a file
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <unistd.h>
int euidaccess(const char *pathname, int mode);
int eaccess(const char *pathname, int mode);
DESCRIPTION
Like access(2), euidaccess() checks permissions and existence of the
file identified by its argument pathname. However, whereas access(2)
performs checks using the real user and group identifiers of the
process, euidaccess() uses the effective identifiers.
mode is a mask consisting of one or more of R_OK, W_OK, X_OK, and F_OK,
with the same meanings as for access(2).
eaccess() is a synonym for euidaccess(), provided for compatibility
with some other systems.
RETURN VALUE
On success (all requested permissions granted), zero is returned. On
error (at least one bit in mode asked for a permission that is denied,
or some other error occurred), -1 is returned, and errno is set to in-
dicate the error.
ERRORS
As for access(2).
VERSIONS
The eaccess() function was added in glibc 2.4.
ATTRIBUTES
For an explanation of the terms used in this section, see at-
tributes(7).
┌────────────────────────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├────────────────────────────────────────────┼───────────────┼─────────┤
│euidaccess(), eaccess() │ Thread safety │ MT-Safe │
└────────────────────────────────────────────┴───────────────┴─────────┘
STANDARDS
These functions are nonstandard. Some other systems have an eaccess()
function.
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: the file permissions may change between the two steps.
Generally, it is safer just to attempt the desired operation and handle
any permission error that occurs.
This function always dereferences symbolic links. If you need to check
the permissions on a symbolic link, use faccessat(2) with the flags
AT_EACCESS and AT_SYMLINK_NOFOLLOW.
SEE ALSO
access(2), chmod(2), chown(2), faccessat(2), open(2), setgid(2), setu-
id(2), stat(2), credentials(7), path_resolution(7)
Linux man-pages 6.03 2022-12-15 euidaccess(3)
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