问题
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- What is the difference between operator “=” and “==” in Bash? 2 answers
In bash, what's the difference, if any, between the equal and double equal test operators?
[[ "a" = "a" ]] && echo equal || echo not-equal
[[ "a" == "a" ]] && echo equal || echo not-equal
[[ "a" = "b" ]] && echo equal || echo not-equal
[[ "a" == "b" ]] && echo equal || echo not-equal
results in:
equal
equal
not-equal
not-equal
回答1:
There's no difference, == is a synonym for = (for the C/C++ people, I assume). See here, for example.
You could double-check just to be really sure or just for your interest by looking at the bash source code, should be somewhere in the parsing code there, but I couldn't find it straightaway.
来源：https://stackoverflow.com/questions/3265803/bash-string-equality