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I am using MSYS and have a file vars.txt with variable, value keys like:

ALLUSERSPROFILE C:/Documents and Settings/All Users

I want to read this in and set environment variables up. I have a bash script setenv:

while read var value;
  echo "performing export $var=$value"
  export $var='$value'

and I call it with

cat vars.txt | source setenv

However in my environment the variables are not set. I also tried making it into a function but no joy. Anybody here know what I'm doign wrong? Thanks.

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setenv is a poor name for your script, since it's the name of a builtin in several shells. –  Daenyth Sep 17 '10 at 18:43
@Daenyth Thanks - yeah it felt kind of wrong at the time but bash doesn't seem to have it. mapenv is a better name anyways ;) –  danio Sep 20 '10 at 8:30

1 Answer 1

up vote 6 down vote accepted

The pipe sets up a subshell. When the subshell exits, the variables are lost.

Try this:

source setenv < vars.txt

Also your single quotes may prevent the expansion of the variable (I don't know if this is true in MSYS). Try changing the export line to this:

export $var="$value"

You can use declare instead of export if the variables don't need to be exported.

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So I have to use temp files? (vars.txt was just for testing) I have a function that generates vars.txt. It works OK with: generate_envmap > /tmp/envmap.txt; apply_env < /tmp/envmap.txt. Would be nicer to do generate_envmap | apply_env. –  danio Sep 20 '10 at 8:50
@danio: I just based my answer on your example. You said you "have a file". I didn't know that you didn't already have the file. You can use process substitution in Bash: source apply_env < <(generate_envmap) –  Dennis Williamson Sep 20 '10 at 13:14
Thanks that seems to be what I want but the MSYS version of bash doesn't seem to have implemented process substitution :-( –  danio Sep 21 '10 at 8:21
@danio: Try using a here string and command substitution: source apply_env <<< $(generate_envmap) –  Dennis Williamson Sep 21 '10 at 10:12
Thanks for that but doesn't seem to do anything. No errors, but no effect either. The temp file solution is a little ugly but fine. –  danio Sep 21 '10 at 11:31

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