In bash how to replace string variable, and set it into sed command

Question

in a bash script file, I have set one variable like this:

    current_path=`pwd`
    sed -i "1s/.*/working_path='$current_path';/" file1.sh

I want to run this script to replace the first line of file1.sh into working_path='$current_path';, but the current_path has the / and in the sed command, the / is predefined in sed replace pattern. And I have tried this:

    current_path1="${current_path/\//\\\/}"

the above line, I want to replace the / in variable current_path into \/, then input the current_path1 into the sed command, but also has an error.

Could you give me some advice, please? Thanks.

possible duplicate of [sed scripting - environment variable substitution](http://stackoverflow.com/questions/584894/sed-scripting-environment-variable-substitution) — tripleee, Nov 24 '14 at 06:30
@tripleee, thank you. That post is very helpful. Maybe I couldn't find that post at that time I faced the question. Or I used different keywords so that the search engine didn't return the index of that post. Thus, I made a new post here. — mining, Nov 24 '14 at 07:18

score 7 · Accepted Answer · answered Oct 29 '13 at 01:23

7

Try this.

sed -i -e "1s@.*@working_path='$current_path';@" file1.sh

Use @ instead of / in the substitute command.

answered Oct 29 '13 at 01:23

Rafa Viotti

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score 2 · Answer 2 · answered Oct 29 '13 at 01:26

2

You can use different delimiters for the s/// command:

current_path=`pwd`
sed -i "1s|.*|working_path='$current_path';|" file1.sh

But you're not really searching and replacing here,, you want to insert the new line and delete the old line:

current_path=`pwd`
sed -i -e "1i\working_path='$current_path)';" -e 1d file1.sh

Are you really changing the first line of a .sh file? Are you deleting the she-bang line?

answered Oct 29 '13 at 01:26

glenn jackman

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Yes, sir, when I run this `sed -i "1s/.*/working_path='\/home\/user\/Desktop';/" file1.sh` in terminal, it worked, but it will replace the `#/bin/bash` into `working_path='/home/user/Desktop;'` – mining Oct 29 '13 at 01:32
My search and replace fails, any idea why? `sed -i "s|\`"$foo"|\`"$bar"/g" "$file"`. The error is: `command substitution: line 28: syntax error: unexpected end of file; sed: -e expression #1, char 22: unterminated \`s' command` – Dennis Feb 26 '14 at 17:01
are those backticks supposed to be there? – glenn jackman Feb 26 '14 at 17:05

Jun Kawai · Answer 3 · 2013-10-29T02:15:37.633

0

Please add a '/' to the beginning of pattern string. It replaces all matches of pattern with string.

 current_path1="${current_path//\//\\\/}"

edited Oct 29 '13 at 02:15

answered Oct 29 '13 at 01:32

Jun Kawai

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Thanks, sir, Rafa's answer, the first answer, works. – mining Oct 29 '13 at 01:37

In bash how to replace string variable, and set it into sed command

3 Answers3