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FlowIt

Member

Registered: 2014-10-25

Posts: 239

[Autotools] Using AC_SUBST for Bash code

In my configure.ac I have something like this:

if cond; then
  HASH_PARSER='${tmp=${sum##*:};tmp=${tmp% *};tmp=${tmp// /}}'
else
  HASH_PARSER=...
fi
AC_SUBST(HASH_PARSER)

I don't know if this is good style or not, but depending on the configure flags this small bash snippet changes, so I can substitute the appropriate "parser".
This example here won't compile, because I get an "unterminated variable reference" error in my Makefile. So I need to escape this snippet in my Makefile but make sure to subsitute it exactly as it is in my configure script. And this is where I am stuck.

Last edited by FlowIt (2016-08-04 23:32:27)

alphaniner

Member

From: Ancapistan

Registered: 2010-07-12

Posts: 2,810

Re: [Autotools] Using AC_SUBST for Bash code

What do you expect '${${${sum##*:}% *}// /}' to do? Assuming it's even syntactically valid, I would think the inner two PEs would have to resolve to variable names and eval would have to be involved somehow.

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FlowIt

Member

Registered: 2014-10-25

Posts: 239

Re: [Autotools] Using AC_SUBST for Bash code

It is supposed to be a chain of string operations, but you are absolutly right, the snippet given is garbage. I edited my first post to show an example which would work in bash, but it not correctly subsituted.

Last edited by FlowIt (2016-08-04 23:33:05)