Quoting special characters with sed

Question

I\'m trying to look in a variable passed to my program (the variable is $1) and to replace any special characters with quoted forms of said special character, in order to no

Answer 1

The problem with what you've done is that you haven't quoted your sed expressions. For example, write

sed s/\*/\\*/

either as

sed 's/\*/\\*/'

or

sed s/\*/\\\\*/

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I'm not sure why do you need that elaborate function in order to escape special characters. You could define a function that would give back the escaped input string:

myescape() { printf "%q" "$1"; }

%q

causes printf to output the corresponding argument in a format that can be reused as shell input.

Another function for passing arguments to sed:

myreplace() { sed "s/$1/$2/" <<< "$3"; }

Now you could invoke it by saying:

myreplace "$(myescape 'pattern')" "replacement" "original_string"

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Example:

$ myescape() { printf "%q" "$1"; }
$ myreplace() { sed "s/$1/$2/" <<< "$3"; }
$ myreplace $(myescape 'a\^a*') 'test' 'aa\^a*aa[aaa]a'
atestaa[aaa]a