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@(#)access.2 8.2 (Berkeley) 4/1/94
.Dd April 1, 1994 .Dt ACCESS 2 .Os .Sh NAME .Nm access .Nd check access permissions of a file or pathname .Sh LIBRARY .Lb libc .Sh SYNOPSIS n unistd.h .Ft int .Fn access "const char *path" "int mode" .Sh DESCRIPTION The .Fn access function checks the accessibility of the file named by .Fa path for the access permissions indicated by .Fa mode . The value of .Fa mode is the bitwise inclusive OR of the access permissions to be checked
f ( Dv R_OK for read permission, .Dv W_OK for write permission and .Dv X_OK for execute/search permission) or the existence test, .Dv F_OK . All components of the pathname .Fa path are checked for access permissions (including .Dv F_OK ) .
p The real user ID is used in place of the effective user ID and the real group access list (including the real group ID) are used in place of the effective ID for verifying permission.
p If a process has super-user privileges and indicates success for .Dv R_OK or .Dv W_OK , the file may not actually have read or write permission bits set. If a process has super-user privileges and indicates success for .Dv X_OK , at least one of the user, group, or other execute bits is set. (However, the file may still not be executable. See .Xr execve 2 . ) .Sh RETURN VALUES If .Fa path cannot be found or if any of the desired access modes would not be granted, then a -1 value is returned; otherwise a 0 value is returned. .Sh ERRORS Access to the file is denied if: l -tag -width Er t Bq Er ENOTDIR A component of the path prefix is not a directory. t Bq Er ENAMETOOLONG A component of a pathname exceeded .Dv {NAME_MAX} characters, or an entire path name exceeded .Dv {PATH_MAX} characters. t Bq Er ENOENT The named file does not exist. t Bq Er ELOOP Too many symbolic links were encountered in translating the pathname. t Bq Er EROFS Write access is requested for a file on a read-only file system. t Bq Er ETXTBSY Write access is requested for a pure procedure (shared text) file presently being executed. t Bq Er EACCES Permission bits of the file mode do not permit the requested access, or search permission is denied on a component of the path prefix. The owner of a file has permission checked with respect to the ``owner'' read, write, and execute mode bits, members of the file's group other than the owner have permission checked with respect to the ``group'' mode bits, and all others have permissions checked with respect to the ``other'' mode bits. t Bq Er EFAULT .Fa path points outside the process's allocated address space. t Bq Er EIO An I/O error occurred while reading from or writing to the file system. .El .Sh SEE ALSO .Xr chmod 2 , .Xr execve 2 , .Xr stat 2 .Sh STANDARDS The .Fn access function conforms to .St -p1003.1-90 . .Sh BUGS .Fn access is a potential security hole and should never be used.
Indexes created Sun Oct 12 22:09:51 GMT 2025