How to write a script to execute files in multiple directories

Question

How do I write a script to execute the files in multiple directories?

The problem is this: I have many directories, and each has a data file to be read and analyzed by a python script (say, a.py). I don't want to "cd" to each of the directories and type "a.py". Outputs are saved in each directory.

Answer 1

find will work magic for you.

find -name datafile.dat -execdir ~/a.py '{}' \; 

The find searches recursively in all subdirectories for files that match a set of rules and performs an action on them.

The -name rule will let you find files with a name that matches what you give it. You can use globbing, for example, "*.dat" would find all the .dat files.

If necessary, you can use -regex instead of -name to match with a regex pattern instead of a glob pattern, so you could do ".*\.dat$" to match all the .dat files.

The -execdir will execute whatever command you give it from the directory of the found file, replacing "{}" with the found file.

Answer 2

You can probably just use a for loop:

for i in first_dir second_dir third_dir; do pushd $i a.py popd done 

It will run pushd $i; a.py; popd with $i set to first_dir, then again with $i as second_dir, and finally $i as third_dir. pushd switches to the given directory, and popd switches back to where you were