-X operators
-r: File is readable by effective uid/gid.
-w: File is writable by effective uid/gid.
-x: File is executable by effective uid/gid.
-o: File is owned by effective uid.
-R: File is readable by real uid/gid.
-W: File is writable by real uid/gid.
-X: File is executable by real uid/gid.
-O: File is owned by real uid.
-e: File exists.
-z: File has zero size (is empty).
-s: File has nonzero size (returns size in bytes).
-f: File is a
plain file.
-d: File is a directory.
-l: File is a symbolic link (false
if symlinks aren't supported by the file system).
-p: File is a named pipe
(FIFO), or Filehandle is a pipe.
-S: File is a socket.
-b: File is a
block special file.
-c: File is a character special file.
-t: Filehandle
is opened to a tty.
-u: File has setuid bit set.
-g: File has setgid bit
set.
-k: File has sticky bit set.
-T: File is an ASCII or UTF-8 text
file (heuristic guess).
-B: File is a "binary" file (opposite of -T).
-M: Script start time minus file modification time, in days.
-A: Same for access
time.
-C: Same for inode change time (Unix, may differ for other
platforms)
