How to change special character in linux using variable

Question

I am using this sed command in particular file, but it doesn't work.

e.g.

a="adsfkndsa%/{}==admfkdsa"  
b=sadkfjdsaklfj  

sed -i -e 's/$a/$b/g' /tmp/sample.txt

Please suggest another way.

Are you actually using this quoting: sed -i -e 's/$a/$b/g", open with single quote and close with double quotes? — , Sep 24 '16 at 06:33
Ya i am try both sed -i -e 's/$a/$b/g' & sed -i -e "s/$a/$b/g" but it is not working — user191625, Sep 24 '16 at 06:39
Could you post an small part of the file that you want to modify? A part that include the string that you want to change. — , Sep 24 '16 at 06:49
Possible duplicate of How can I use variables when doing a sed? — Eric Renouf, Sep 24 '16 at 13:30
The question was clear enough, and a duplicate - but not that one. — Thomas Dickey, Sep 24 '16 at 14:01

score 3 · Answer 1 · 2016-09-24T07:18:54.740

3

I just tried this, and it works on my system (Debian 8):

sed -i.bak "s|$a|$b|g" /tmp/sample.txt

You need to change the delimiter, since the variable $a contains a /.

Before:

cat /tmp/sample.txt.bak 
foo
adsfkndsa%/{}==admfkdsa
bar

After:

cat /tmp/sample.txt
foo
sadkfjdsaklfj
bar

Edit, sed version info:

sed --version
sed (GNU sed) 4.2.2

edited Sep 24 '16 at 07:18

answered Sep 24 '16 at 07:08

1 Answers1