Appending line with special characters in shell

Question

I want to appends each line of the file as below:

file.txt :

adminsrv.tar

Output:

- archive: "packages/images/adminsrv.tar"

I tried several method like the one below and ended up with error:

input=/var/tmp/file.txt  
while read -r line
Do
sed -i 's|$line|" - archive: "packages//images//$line"'
done < $input

`Do` is spelled incorrectly. But why do you use a loop and `sed` at all? A sole `echo -- "- archive: "packages/images/$( — user1934428, Aug 10 '22 at 06:43
I also don't understand what you mean by _special characters_. — user1934428, Aug 10 '22 at 06:43

score 1 · Accepted Answer · answered Aug 10 '22 at 06:23

1

You can just insert new text before every line using sed and there is no need to run a shell loop:

sed 's~.*~- archive: "packages/images/&"~' "$input"

- archive: "packages/images/adminsrv.tar"

This sed uses .* for search for any text and then it substitutes matched text with replacement text and & which is back-reference of the matched text.

answered Aug 10 '22 at 06:23

anubhava

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I liked the use of the alternative delimiters :) – David C. Rankin Aug 10 '22 at 08:10

score 1 · Answer 2 · edited Aug 10 '22 at 08:09

1

Perhaps, if you want to edit in place

sed -i'' -Ee 's@^(.*)$@- archive: "packages/images/\1"@' file.txt

Check man sed.

edited Aug 10 '22 at 08:09

David C. Rankin

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answered Aug 10 '22 at 06:30

Diego Torres Milano

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the above expression throws another error :sed: -e expression #1, char 43: invalid reference \1 on `s' command's RHS – suryakant pasayat Aug 10 '22 at 06:42
1

Remove the `'\'` from `$` and `$` they are not used with Extended REGEX. – David C. Rankin Aug 10 '22 at 07:18
@DavidC.Rankin, totally agree, however on macOS without escaping: `sed: 1: "s@^(.*)$@- archive: "pa ...": \1 not defined in the RE` – Diego Torres Milano Aug 10 '22 at 14:48
@DiegoTorresMilano - yes, I'm a bit Mac illiterate. it's been 35 years since I used the square boxes `:)` – David C. Rankin Aug 10 '22 at 18:41
@DavidC.Rankin no worries, and it's a macOS bug because `man` claims: "An atom is a regular expression enclosed in `()'" (not escaped). – Diego Torres Milano Aug 10 '22 at 18:46

Appending line with special characters in shell

2 Answers2