Is there any difference between '=' and '==' operators in bash or sh
bash, linux, operators, shell
Solution
Inside single brackets for condition test (i.e. [ ... ]), single = is supported by all shells, where as == is not supported by some of the older shells.
Inside double brackets for condition test (i.e. [[ ... ]]), there is no difference in old or new shells.
Edit: I should also note that: Always use double brackets [[ ... ]] if possible, because it is safer than single brackets. I'll illustrate why with the following example:
if [ $var == "hello" ]; then
if $var happens to be null / empty, then this is what the script sees:
if [ == "hello" ]; then
which will break your script. The solution is to either use double brackets, or always remember to put quotes around your variables ("$var"). Double brackets is better defensive coding practice.
Problem
I realized that both '=' and '==' operators works in if statement. For example: ``` var="some string" if [ "$var" == "some string" ];then #doing something fi if [ "$var" = "some string" ];then #doing something fi ``` Both if statement above worked well in bash and sh. I just wondered if there is any difference between them? Thanks...