euidaccess, eaccess - check effective user's permissions for a file
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).
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 appropriately.
As for access(2).
The eaccess() function was added to glibc in version 2.4.
These functions are nonstandard. Some other systems have an eaccess() function.
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.
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