sed rare-delimiter (other than & | / ?…)

Question

I\'ve to apply the Unix command sed on a string (can contain #, !, /, ?, &, @ and all other characters) which can contains all types of

Answer 1

There's no universal separator, but it can be escaped by a backslash for sed to not treat it like separator (at least unless you choose a backslash character as separator).

Depending on the actual application, it might be handy to just escape those characters in both pattern and replacement.

If you're in a bash environment, you can use bash substitution to escape sed separator, like this:

safe_replace () {
    sed "s/${1//\//\\\/}/${2//\//\\\/}/g"
}

It's pretty self-explanatory, except for the bizarre part. Explanation to that:

${1//\//\\\/}
${            - bash expansion starts
  1           - first positional argument - the pattern
   //         - bash pattern substitution pattern separator "replace-all" variant
     \/       - literal slash
       /      - bash pattern substitution replacement separator
        \\    - literal backslash
          \/  - literal slash
            } - bash expansion ends

example use:

$ input="ka/pus/ta"
$ pattern="/pus/"
$ replacement="/re/"
$ safe_replace "$pattern" "$replacement" <<< "$input"
ka/re/ta