using regex with sed on mac doesn't produce expected result

Question

I have file containing following lines that I want to adjust with script.

module.exports = {
  parserOptions: {
    project: ['./tsconfig.json'],
  },
... more stuff here
}

so it looks like this. I dont really care about whitespaces in the result.

module.exports = {
  parserOptions: {
    project: ['./tsconfig.json'],
    tsconfigRootDir: __dirname
  },
... more stuff here
}

What I have now is:

sed -r "s/project:\s*\['.\/tsconfig.json'\],/project:\['.\/tsconfig.json'\],\ntsconfigRootDir\:__dirname/g" filename

but it doesnt get matched. I tried the matching pattern on this site https://sed.js.org/index.html?snippet=y7KG95 and there I get the result I want. I also tried using sed -E but no luck.

I would say the script setup works OK because changing something simple like s/project/projectA/g works fine.

Thanks!

Using macOS Monterey 12.5.1

Answer 1

You're using -r, \s, and \n in the replacement which are all GNUisms (well \s is more of a perl'ism). The \: is also non-standard. And you have missing \ in fronts of the .s

Standardly, the syntax would be:

sed 's@^\([[:blank:]]*\)project:[[:blank:]]*\['\''\./tsconfig\.json'\''\]@&,\
\1tsconfigRootDir: __dirname@g' filename

[[:blank:]] in place of \s (well, \s would be more [[:space:]] but here it should be enough to match blanks (\h in perl)), \ followed by newline to include a newline in the replacement.

We capture the leading blanks on the project line to indent the added line with the same indentation (\1 recalls that capture group).

To check the syntax of your sed implementation and version, check its documentation, with man or info, not some random page on the internet that could be describing a different implementation or version.

See also the POSIX 2018 standard specification of the sed utility there.