Re: Why is this executed inside a subshell?

[Chet Ramey]

Com MN PG P E B Consultant 3 wrote:
> Consider the following program:
> 
> #!/usr/local/bin/bash --norc
> export VAR=A
> function setvar
> {
>   VAR=B
>   echo X
> }
> V=$(setvar)
> echo $VAR
> 
> When I execute it, I get as result "A", not "B", as I had expected.

Posix requires that command substitution be executed in a "subshell
environment."  It forbids changes to the subshell environment affecting
the calling shell's environment.  The way to do that is to run command
substitutions in an actual subshell and communicate via pipes.

Chet

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Chet Ramey, ITS, CWRU    chet@case.edu    http://cnswww.cns.cwru.edu/~chet/