File Test Operators

These unary operators take one argument, either a filename or a filehandle, and test the associated file to see if something is true about it. If the argument is omitted, they test $_ (except for -t, which tests STDIN). If the special argument _ (underscore) is passed, they use the information from the preceding test or stat call.

• -r -w -x
• File is readable/writable/executable by effective uid/gid.
• -R -W -X
• File is readable/writable/executable by real uid/gid.
• -o -O
• File is owned by effective/real uid.
• -e -z
• File exists/has zero size.
• -s
• File exists and has non-zero size. Returns the size.
• -f -d
• File is a plain file/a directory.
• -l -S -p
• File is a symbolic link/a socket/a named pipe (FIFO).
• -b -c
• File is a block/character special file.
• -u -g -k
• File has setuid/setgid/sticky bit set.
• -t
• Tests if filehandle (STDIN by default) is opened to a tty.
• -T -B
• File is a text/non-text (binary) file. -T and -B return true on a null file, or a file at EOF when testing a filehandle.
• -M -A -C
• File modification/access/inode-change time. Measured in days. Value returned reflects the file age at the time the script started. See also $^T in the section called "Special Variables".