Linux in a Nutshell, 6th Edition

Name

[[ ]]

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.

Additional operators

&&

Logical AND of test expressions (short circuit).

||

Logical OR of test expressions (short circuit).

<

First string is lexically “less than” the second.

>

First string is lexically “greater than” the second.