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I know lot of questions have been written about it, but didn't work for me. I am working in bash, and would like replace a string with escaped special characters:

echo "abm1c/def/sdfd/sync/sdff.jar/rtets.jar/fg/gdf/ggdg/dg/adg/TextParser$2.class," | sed -e "s#\([]*^+\.\$[-]\)##g"

Obviously output was incorrect. Can you please provide me with the correct sed command.

  • 2
    correct command for what? What output did you want? – Zanna Jul 25 '17 at 7:47
  • I don't like the escaping with normal sed. Extended Regex with using -E is much more familiar. – pLumo Jul 25 '17 at 7:54
  • I want to escape the special characters in above string. Like forward slash, dollar sign, singe dot , – Soumali Chatterjee Jul 25 '17 at 7:54
  • 2
    Please edit your question and show us your expected output so we can be sure we are giving you what you expect. – terdon Jul 25 '17 at 7:55
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Your regular expression is wrong. It looks like you are trying to use \( \) to define a character class. You can't. Those are capture groups, they let you refer to what was matched inside them as \1 (or \2, \3 for subsequent groups). A character class is defined using []. What you want to do is capture any match of the character class to replace it with itself escaped:

$ echo 'abm1c/def/sdfd/sync/sdff.jar/rtets.jar/fg/gdf/ggdg/dg/adg/TextParser$2.class,' |
    sed -e 's#\([]*^+.$[/]\)#\\\1#g'

Note that you aklso need the ] to be the first character in the character class. Otherwise, it is assumed to be the closing bracket. And you don't need to escape . or $ when they're within a character class.

Finally, you could do this sort of thing more simply by using perl's quotemeta:

$ echo 'abm1c/def/sdfd/sync/sdff.jar/rtets.jar/fg/gdf/ggdg/dg/adg/TextParser$2.class,' | 
    perl -lne 'print quotemeta()'
abm1c\/def\/sdfd\/sync\/sdff\.jar\/rtets\.jar\/fg\/gdf\/ggdg\/dg\/adg\/TextParser\$2\.class\,
  • Thanks! it is working, but can we use this for all escape characters i.e.: ;'"`#$&*?[]<>{}\ as well? – Soumali Chatterjee Jul 25 '17 at 13:01
  • @SoumaliChatterjee what do you mean? Did you try it with those characters and it failed? – terdon Jul 25 '17 at 13:02
  • @SoumaliChatterjee echo ";'\"`#$&*?[]<>{}\ " | perl -ne 'print quotemeta' – terdon Jul 25 '17 at 13:06
  • Ofcourse, with my test case, like String "abm1c/def/sdfd/sync/sdff.jar", or "abm1c/def/sdfd/" it didn't. I am trying to understand if there may be any special character, which I have missed to include? Thanks – Soumali Chatterjee Jul 25 '17 at 13:26
  • @SoumaliChatterjee no character is "special" in general. It will always depend on where you want to use them. But yes, perl's quotemeta will escape everything that isn't a simple ASCII word character (so everything that doesn't match [A-Za-z_0-9]). – terdon Jul 25 '17 at 13:27

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