April 1, 1994 ACCESS 2

### NAME

access - check access permissions of a file or pathname

### LIBRARY

Standard C Library (libc, -lc)

### SYNOPSIS

```int` access(```const char *path``, int mode`)

### DESCRIPTION

The access(``) function checks the accessibility of the file named by ```path` for the access permissions indicated by ```mode`. The value of ```mode` is the bitwise inclusive OR of the access permissions to be checked (```R_OK` for read permission, ```W_OK` for write permission and ```X_OK` for execute/search permission) or the existence test, ```F_OK`. All components of the pathname ```path` are checked for access permissions (including ```F_OK`).

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.

If a process has super-user privileges and indicates success for ```R_OK` or ```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 ```X_OK`, at least one of the user, group, or other execute bits is set. (However, the file may still not be executable. See execve(2).)

### RETURN VALUES

If ```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.

### ERRORS

Access to the file is denied if:

[```ENOTDIR`]
  A component of the path prefix is not a directory.

[```ENAMETOOLONG`]
  A component of a pathname exceeded ```{NAME_MAX}` characters, or an entire path name exceeded ```{PATH_MAX}` characters.

[```ENOENT`]
  The named file does not exist.

[```ELOOP`]
  Too many symbolic links were encountered in translating the pathname.

[```EROFS`]
  Write access is requested for a file on a read-only file system.

[```ETXTBSY`]
  Write access is requested for a pure procedure (shared text) file presently being executed.

[```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.

[```EFAULT`]
  ```path` points outside the process's allocated address space.

[```EIO`]
  An I/O error occurred while reading from or writing to the file system.

### SEE ALSO

chmod(2), execve(2), stat(2)

### STANDARDS

The access(``) function conforms to ISO/IEC 9945-1:1990 (``POSIX.1'') .

### BUGS

access(``) is a potential security hole and should never be used.