removing a case clause: bash expansion in sed regexp: X='a\.b' ; Y=';;' sed -n '/${X}/,/${Y}/d'
- by ChrisSM
I'm trying to remove a case clause from a bash script. The clause will vary, but will always have backslashes as part of the case-match string.
I was trying sed but could use awk or a perl one-liner within the bash script.
The target of the edit is straightforward, resembles:
$cat t.sh
case N in
a\.b);
#[..etc., varies]
;;
esac
I am running afoul of the variable expansion escaping backslashes, semicolons or both. If I 'eval' I strip my backslash escapes. If I don't, the semi-colons catch me up. So I tried subshell expansion within the sed. This fouls the interpreter as I've written it. More escaping the semi-colons doesn't seem to help.
X='a\.b' ; Y=';;'
sed -i '/$(echo ${X} | sed -n 's/\\/\\\\/g')/,/$(echo ${Y} | sed -n s/\;/\\;/g')/d t.sh
And this:
perl -i.bak -ne 'print unless /${X}/ .. /{$Y}/' t.sh # which empties t.sh
and
eval perl -i.bak -ne \'print unless /${X}/ .. /{$Y}/' t.sh # which does nothing
