Replace string in a file with url present in another file in shell script

Question

I was like trying to replace a string in a file with the url present in another file using sed command. for example... let url.txt be the file that contains url:

https://stackoverflow.com/questions/1483721/shell-script-printing-contents-of-variable-containing-output-of-a-command-remove

and demo.txt contains Replace_Url the sed command I used is:

sed -i "s/Replace_Url/$(sed 's:/:\\/:g' url.txt)/" demo.txt

there comes no error but the string hasn't been replaced..

`sed -i "s@Replace_Url@$( – F. Hauri - Give Up GitHub Mar 16 '22 at 16:43 — F. Hauri - Give Up GitHub, Mar 16 '22 at 16:43

Sneha · Answer 1 · 2022-03-17T04:32:04.883

0

sed -i "s@Replace_Url@$(<url.txt)@" demo.txt it works

edited Mar 17 '22 at 04:32

answered Mar 17 '22 at 03:56

Sneha

3
2

That would fail given various contents of `url.txt`, e.g. `&` or `\1` or `@`. – Ed Morton Mar 19 '22 at 11:59
1

Please read "[answer]" and "[Explaining entirely code-based answers](https://meta.stackoverflow.com/q/392712/128421)". It helps more if you supply an explanation why this is the preferred solution and explain how it works. We want to educate, not just provide code. – the Tin Man Mar 20 '22 at 23:02

score 0 · Accepted Answer · answered Mar 19 '22 at 12:07

It'd be hard to do this job robustly with sed since sed doesn't support literal string operations (see Is it possible to escape regex metacharacters reliably with sed), so just use awk instead, e.g.:

awk -v old='Replace_Url' '
    NR==FNR { new=$0; next }
    s=index($0,old) { $0 = substr($0,1,s-1) new substr($0,s+length(old)) }
    { print }
' url.txt demo.txt

Replace string in a file with url present in another file in shell script

2 Answers2