bash Pocket Reference

Name

[[ ]] — Extended version of the test command.

Synopsis

[[ expression ]]

Same as test expression or [ expression ], except that [[ ]] allows additional operators. Word splitting and filename expansion are disabled. Note that the brackets ([ ]) are typed literally, and that they must be surrounded by whitespace. See test.

Additional Operators

&&	Logical AND of test expressions (short circuit).
||	Logical OR of test expressions (short circuit).
<	First string is lexically “less than” the second, based on the locale’s sorting order. (However, see the description of the compat31, compat32, and compat40 options in the section Shell Options.)
>	First string is lexically “greater than” the second, based on the locale’s sorting order. (However, see the description of the compat31, compat32, and compat40 options in the section Shell Options.)