Re:Pure Bash Bible
by zests on Thursday September 19, 2019 @09:32AM
(#21015968)
Single square bracket conditionals [] are the "older" (POSIX) version but do not have certain features that we would like to use in our shell scripts. Bash uses double square brackets to extend the functionality.
This is my understanding. Possibly not 100% correct but essentially correct enough for me to understand the reason/rationale for the difference.
Re:Pure Bash Bible
by joombaga on Thursday September 19, 2019 @10:55AM
(#21016761)
You got it! `test` is a shell builtin. `[` is basically syntactic sugar, and is a synonym for `test` with the additional requirement that the last argument must be a closing bracket `]`. `[[` is a shell keyword with more features.
This is my understanding. Possibly not 100% correct but essentially correct enough for me to understand the reason/rationale for the difference.