-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.
 -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 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 platform