bash Cookbook

Test Operators

The operators in Test Operators are used with test and the […] and [[…]] constructs. They can be logically combined with -a (“and”) and -o (“or”) and grouped with escaped parenthesis (\(…\)). The string comparisons < and > and the [[…]] construct are not available in versions of bash prior to 2.0, and =~ is only available in bash version 3.0 and later as noted.

Table A-9. Test operators

Operator	True if
-a file	file exists, deprecated, same as -e
-b file	file exists and is a block device file
-c file	file exists and is a character device file
-d file	file exists and is a directory
-e file	file exists; same as -a
-f file	file exists and is a regular file
-g file	file exists and has its setgid bit set
-G file	file exists and is owned by the effective group ID
-h file	file exists and is a symbolic link, same as -L
-k file	file exists and has its sticky bit set
-L file	file exists and is a symbolic link, same as -h
-n string	string is non-null
-N file	file was modified since it was last read
-O file	file exists and is owned by the effective user ID
-p file	file exists and is a pipe or named pipe (FIFO file)
-r file	file exists and is readable
-s file	file exists and is not empty
-S file	file exists and is a socket
-t N	File descriptor N points to a terminal
-u file	file exists and has its setuid bit set
-w file	file exists and is writeable
-x file	file exists and is executable, or file is a directory that can be searched
-z string	string has a length of zero
fileA -nt fileB	fileA modification time is newer than fileA ...