Perl in a Nutshell, 2nd Edition

File Test Operators

A file test operator is a unary operator that tests a filename or a filehandle.

Operator	Meaning
-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
-s	File has nonzero size (returns size)
-f	File is a plain file
-d	File is a directory
-l	File is a symbolic link
-p	File is a named pipe (FIFO)
-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 a text file
-B	File is a binary file (opposite of -T)
-M	Age of file (at startup) in days since modification
-A	Age of file (at startup) in days since last access
-C	Age of file (at startup) in days since inode change