This is pretty basic, I have a folder with several subfolders of JS files and i want to run Google's Clojure compiler on all of the files in those folders. The command to process a single file is as follows:

java -jar compiler.jar --js filename.js --js_output_file newfilename.js

How do I modify this to run on every JS file in my directory structure?


You can use find:

find . -name "*.js" -exec java -jar compiler.jar --js {} --js_output_file new{} \;
  • Thanks, and i can probably leverage this to rename everything because the original JS files needs to be overwritten – Mataniko Jun 27 '13 at 8:00
  • In case the --js and --js_output_file need to differ I would make a two-line script that takes the filename as a parameter, write output to temporary file and mv the file to the original name. – Anthon Jun 27 '13 at 8:07
  • If you want to avoid creating a separate script find -name '*.js' | while read jsfile; do java -jar compiler.jar --js "$jsfile" --js_output_file "new$jsfile" && mv "new$jsfile" "$jsfile"; done should do the trick. – David Baggerman Jun 27 '13 at 8:17
  • find -exec is great for simple commands. for complex ones find | xargs is much better and also it allows to run commands in parallel. – rush Jun 27 '13 at 8:22
  • @rush maybe explain why xargs is better? – Mel Boyce Jun 27 '13 at 12:39

You can also use a simple for loop, especially if the files are within a single directory (no subdirectories). It can be modified to work with subdirectories as well.

Without recursion:

for filename in ./*.js
    java -jar compiler.jar --js "${filename}" --js_output_file "new${filename}"

or as an equivalent one-liner:

for filename in ./*.js; do java -jar compiler.jar --js "${filename}" --js_output_file "new${filename}"; done

To recurse into subdirectories (requires GNU bash 4.0 or newer) (thanks @ChrisDown):

shopt -s globstar
for filename in ./**/*.js; do
    java -jar compiler.jar --js "${filename}" --js_output_file "new${filename}"
  • 1
    This does not recurse subdirectories as asked in the question. With bash4+, you can use globstar to do so. – Chris Down Jun 27 '13 at 7:58
  • 1
    Yep, it's a good answer and great to know, but the other answer does exactly what i need it to. – Mataniko Jun 27 '13 at 8:01
  • 1
    Ohh, I managed to completely miss the "several subfolders" part. Sorry. Leaving the answer around for completeness' sake, though. – a CVn Jun 27 '13 at 8:06
  • 3
    @rush Since ** can match an arbitrary level of recursion, **/*.js works: sprunge.us/PXQK – Chris Down Jun 27 '13 at 9:02
  • 1
    It's generally a good idea to use for f in ./*.js; do or for f in ./**/*.js; do in order to protect yourself from filenames beginning with a - (I don't know if that's necessary in this case, but it's a good habit anyway). – evilsoup Jun 27 '13 at 16:01

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