Replace a string in shell script by a string with special character

Question

I am trying to replace a string inside a shell script by a string with special character:

name="test&commit"
echo "{{name}}" | sed "s/{{name}}/$name/g"

and the result I am getting is

test{{name}}commit

I know that adding \ before & will make it work but the name param is given by the user so I'd like my code to somoehow predict that. Do anybody knows how to achieve this ?

score 2 · Accepted Answer · answered Apr 17 '15 at 09:03

2

You need to use another sed command to add a backslash before all the special characters in the given input string.

$ name="test&commit"
$ name1=$(sed 's/[^[:alpha:][:digit:][:blank:]]/\\&/g' <<<"$name")
$ echo $name1
test\&commit
$ echo "{{name}}" | sed "s/{{name}}/$name1/g"
test&commit

It would be minimized as,

$ name="test&commit"
$ echo "{{name}}" | sed "s/{{name}}/$(sed 's/[^[:alpha:][:digit:][:blank:]]/\\&/g' <<<"$name")/g"
test&commit

answered Apr 17 '15 at 09:03

Avinash Raj

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Does this `name1=$(sed 's/[[:punct:]]/\\&/g' <<<"$name")` also suit ? We could add maybe the `[:cntrl:]` also for special character if allowed. – NeronLeVelu Apr 17 '15 at 09:13
`cntrl` class is to add to `punct`, not replace :-) – NeronLeVelu Apr 17 '15 at 09:19
All you actually need is `sed 's/[&/\]/\\&/g'`. See http://stackoverflow.com/a/29626460/1745001. – Ed Morton Apr 17 '15 at 19:06

JJoao · Answer 2 · 2015-04-24T11:36:10.507

1

Slightly change way of providing the template and values:

$ cat template

   Dear {{name}}
    I hope to see you {{day}}.

(template is a file with {{var}}, to be instantiated with values)

$ name='Mary&Susan' day=tomorrow    perl -pe 's/{{(\w+)}}/$ENV{$1}/g' template

   Dear Mary&Susan,
    I hope to see you tomorrow.

edited Apr 24 '15 at 11:36

answered Apr 17 '15 at 14:47

JJoao

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score 0 · Answer 3 · answered Apr 17 '15 at 10:09

In perl you can turn off expressions with \Q \P.
I fill the vars template, placeholder and name:

$ echo "template=$template"
template=The name is {{name}} and we like that.
$ echo "placeholder=$placeholder"
placeholder={{name}}
$ echo "name=$name"
name=test&commit

The replacement will be performed with

$ echo $template | perl -pe 's/\Q'$placeholder'\E/'$name'/g'
The name is test&commit and we like that.

Replace a string in shell script by a string with special character

3 Answers3