Replacing line with unescaped text

beazizo · 10-08-2009, 08:55 AM

I'm struggling to find a solution to this problem. I want the script below to output foo="\${var}/test" but it outputs foo="${var}/test". It seems sed (or shell) unescapes $prop and removes the backslash in front of ${var}/test.

The value of prop is fixed meaning it can't be double slashed.

I don't want to use awk, only sed.

Am I missing something obvious?

This script is just a trimmed down version of what my script really does to show the problem I'm trying to solve.

#!/bin/bash

prop='foo="\${var}/test"'
prop_name="${prop%%=*}"

echo $prop # Outputs correctly

echo 'foo="should-get-replaced"' | sed 's|^[ \t]*'"$prop_name"'[ \t]*=.*$|'"$prop"'|'

# Outputs: foo="${var}/test"
# Needs to Output: foo="\${var}/test"

vonbiber · 10-08-2009, 10:55 AM

Code:

!/bin/bash

prop='foo="\${var}/test"'
prop_name="${prop%%=*}"

echo $prop # Outputs correctly

echo 'foo="should-get-replaced"' | \
        sed 's|^[ \t]*'"$prop_name"'[ \t]*=.*$|'"$prop"'|'

echo 'foo="should-get-replaced"' | \
        sed 's|^[ \t]*'"$prop_name"'[ \t]*=.*$|'"$prop"'|' | \
        sed 's?^\([^"]*"\)?\1\\?'

should output

Code:

foo="\${var}/test"
foo="${var}/test"
foo="\${var}/test"