Map .gitignore / .npmignore to tar exclusion

Question

Say I have a .gitignore or .npmignore file with the following contents:

logs
*.sh
*.log

not that .npmignore files are designed to be interpreted just like .gitignore files.

My question is - how can I use the contents of a standard .npmignore / .gitignore file and map them to --exclude options for a tar command?

basically I need to do something like this:

find -not -path (whatever is in gitignore) | tar

or just this:

tar --exclude="whatever matches gitignore/npmignore"

the latter just seems fine, but how can I map what's in .gitignore / .npmignore to the command line? Is there some package that can do that?

Answer 1

As I suspected, it looks .gitignore / .npmignore are designed to map directly to command line tools, like find, tar, etc.

So in Node.js/TypeScript code, I just have this, and it seems to work:

   const keep: Array<RegExp> = [
     /^README/i,
     /^package\.json$/,
     /^LICENSE/i,
     /^LICENCE/i,
     /^CHANGELOG/i
   ];

    export const npmIgnoreToArray = function (npmignore: string): Array<string> {
      return String(npmignore).trim().split('\n').map(v => String(v).trim())
        .filter(Boolean)
        .filter(v => !v.startsWith('#'))
        .filter(function (v) {
          return !keep.some(function (rgx) {
            return rgx.test(v);
          })
        });
    };

    export const npmIgnoreToTARExclude = function (npmignore: Array<string>): string {
      return npmignore.map(function (v) {
          return `--exclude='${v}'`;
        })
        .join(' ')
    };