Use variable inside double quotes inside single quotes in sed

Question

I want to search for a string enclosed in double quotes given by a positional parameter. This is what I've done:

    #!/bin/bash

    FOO=$0

    sed -i 's/"${FOO}"/bar/m' file.txt

Neither "$FOO" nor \"a${FOO}\"/ work.

I am aware that for variables to be expanded, you have to enclose the whole regex in double quotes (sed substitution with bash variables). The thing is that the string I am searching for is also enclosed in double quotes, that is why I enclosed the whole regex in single quotes. I also tried to enclose it in double quotes and escaping the double quotes, but it didn't work.

An explanation of the logic behind single and double quotes escaping would be really useful.

nu11p01n73R · Accepted Answer · 2014-11-04T20:58:53.473

2

Use double quotes to quote the sed commands as

sed -i "s/\"${FOO}\"/bar/m" file.txt

Test:

$ echo $b
hello
$ echo \"hello\" | sed "s/\"$b\"/asdf/"
asdf

edited Nov 04 '14 at 20:58

answered Nov 04 '14 at 19:51

nu11p01n73R

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Will this match "foo" (including the quotes) if the positional parameter is "foo" (without the quotes)? – Federico Nov 04 '14 at 19:53
Sorry i didnt get you – nu11p01n73R Nov 04 '14 at 19:58
I want to search for: "blaba", not blabla. I expect that the string passed to the script will not be enclosed in double quotes, but the text that I have to find is. – Federico Nov 04 '14 at 20:15
@Federico i have edited the answer to include that as well. Hope it helps now – nu11p01n73R Nov 04 '14 at 20:35
1

Hmm. It's not working. Now the command output throws an error `sed: -e expression #1, char 12: unknown option to `s'` – Federico Nov 04 '14 at 20:55
@Federico check the edit. I have added an example to make it clear – nu11p01n73R Nov 04 '14 at 20:59
Now it works! Thank you. – Federico Nov 04 '14 at 21:11
@Federico you are welcome :) – nu11p01n73R Nov 04 '14 at 21:13

Use variable inside double quotes inside single quotes in sed

1 Answers1