Replace Environment Variable in argument to shell script

Question

I've got a shell script that gets called with arguments that contain variable names. I want the variable to be replaced with their values. Consider the example below: It solves my problem, but it uses eval. I want to avoid eval for security reasons.

#!/bin/bash
#
# example:
# $> replace.sh arg '$VAR'
# arg value

VAR=value
ARGS=$(eval echo $*)

echo $ARGS

seen this? - http://stackoverflow.com/questions/10820343/how-can-i-generate-new-variable-names-on-the-fly-in-a-shell-script — Dummy00001, Oct 22 '15 at 13:25

score 2 · Answer 1 · answered Oct 22 '15 at 14:32

2

You are looking for indirect variable expansion:

$ SPY1=SPY2
$ SPY2="Lance Link"
$ SPY=${!SPY1}
$ echo $SPY
Lance Link
$

answered Oct 22 '15 at 14:32

Gary_W

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score 1 · Accepted Answer · answered May 11 '16 at 13:42

Works for me with something like:

#!/bin/bash
#
# example:
# $> replace.sh arg '$VAR'
# arg value

VAR=value
ARGS=""
for arg in "$@"
do
  arg="${arg/$/}" # remove preceding $ for indirect variable expansion to work
  ARGS="${ARGS} ${!arg}"
done

echo "$ARGS"

Replace Environment Variable in argument to shell script

2 Answers2