ACCESS(2)                            SysV                            ACCESS(2)



NAME
     access - Determine the accessibility of a file

SYNOPSIS
     #include <unistd.h>
     int access (path, access_mode)
     const char *path;
     int access_mode;

DESCRIPTION
     The access function checks for accessibility of the file specified by a
     pathname.

     The path argument points to the file pathname. When the path argument
     refers to a symbolic link, the access function returns information about
     the file pointed to by the symbolic link.

     Permission to access all components of the path argument is determined by
     using a real user ID instead of an effective user ID, a group access list
     (including a real group ID) instead of an effective group ID.

     access_mode specifies the type of access. The bit pattern contained in
     the access_mode argument is constructed by a logical OR of the following
     values:
     R_OK   Checks read permission.
     W_OK   Checks write permission.
     X_OK   Checks execute (search) permission.
     F_OK   Checks to see if the file exists.

     Specifying mode as F_OK (that is, 0) tests whether the directories
     leading to the file can be searched and the file exists.

     If any access permissions are to be checked, each is checked
     individually.

     If the process making the call has ROOT privileges, success if returned
     for X_OK, R_OK or W_OK -- even if none of these file permission bits are
     set.

     Notice that only access bits are checked.  A directory may be indicated
     as writable by access, but an attempt to open it for writing will fail
     (although files can be created there); a file may look executable, but
     exec will fail unless it is in proper format.

DIAGNOSTICS
     Upon successful completion, the access returns a value of 0 (zero).
     Otherwise, a value of -1 is returned and errno is set to indicate the
     error.

ERRORS
     If the access function fails, access to the file specified by the path
     argument is denied and errno is set to one of the following values:

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

     [EINVAL]       The value of access_mode is invalid.

     [ENAMETOOLONG] A component of a pathname exceeded PATH_MAX characters, or
                    an entire pathname exceeded NAME_MAX characters.

     [ENOENT]       The named file does not exist or path points to an empty

                    string.

     [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.

     [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 that is being executed.

     [EFAULT]       The path argument points outside the process' allocated
                    address space.

     [EINTR]        A signal was caught during the access system call.

SEE ALSO
     chmod(2), stat(2), chown(2), <unistd.h>.