-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.
                -B  File is a "binary" file (opposite of -T).

                -M  Age of file in days when script started.
                -A  Same for access time.
                -C  Same for inode change time.