Learning Linux Shell Scripting - Second Edition

Logical test operators

The following are the various options for logical operations using test, which is taken from the Bash reference manual available at http://www.gnu.org/software/bash/:

Test Operator	Tests True If
[ string_1 -a string_1 ]	Both string_1 and string_2 are true
[ string_1 -o string_2 ]	Either string_1 or string_2 is true
[ ! string_1 ]	Not a string_1 match
[[ pattern_1 && pattern_2 ]]	Both pattern_1 and pattern_2 are true
[[ pattern_1 || pattern_2 ]]	Either pattern_1 or pattern_2 is true
[[ ! pattern ]]	Not a pattern match

 

We can use the test operator for strings along with pattern matching as follows:

$ name=Ganesh $ [[ $name == [Gg]anesh ]] # Wildcards allowed $ echo $? 0 ...