Find the name of subdirectories and process files in each - linux

Question

Let's say /tmp has subdirectories /test1, /test2, /test3 and so on,
and each has multiple files inside.
I have to run a while loop or for loop to find the name of the directories (in this case /test1, /test2, ...)
and run a command that processes all the files inside of each directory.
So, for example,
I have to get the directory names under /tmp which will be test1, test2, ...
For each subdirectory, I have to process the files inside of it.
How can I do this?
Clarification:
This is the command that I want to run:
find /PROD/140725_D0/ -name "*.json" -exec /tmp/test.py {} \;
where 140725_D0 is an example of one subdirectory to process - there are multiples, with different names.
So, by using a for or while loop, I want to find all subdirectories and run a command on the files in each.
The for or while loop should iteratively replace the hard-coded name 140725_D0 in the find command above.

Answer 1

You should be able to do with a single find command with an embedded shell command:
find /PROD -type d -execdir sh -c 'for f in *.json; do /tmp/test.py "$f"; done' \;
Note: -execdir is not POSIX-compliant, but the BSD (OSX) and GNU (Linux) versions of find support it; see below for a POSIX alternative.
The approach is to let find match directories, and then, in each matched directory, execute a shell with a file-processing loop (sh -c '<shellCmd>').
If not all subdirectories are guaranteed to have *.json files, change the shell command to for f in *.json; do [ -f "$f" ] && /tmp/test.py "$f"; done
Update: Two more considerations; tip of the hat to kenorb's answer:
By default, find processes the entire subtree of the input directory. To limit matching to immediate subdirectories, use -maxdepth 1[1]:
find /PROD -maxdepth 1 -type d ...
As stated, -execdir - which runs the command passed to it in the directory currently being processed - is not POSIX compliant; you can work around this by using -exec instead and by including a cd command with the directory path at hand ({}) in the shell command:
find /PROD -type d -exec sh -c 'cd "{}" && for f in *.json; do /tmp/test.py "$f"; done' \;
[1] Strictly speaking, you can place the -maxdepth option anywhere after the input file paths on the find command line - as an option, it is not positional. However, GNU find will issue a warning unless you place it before tests (such as -type) and actions (such as -exec).

Answer 2

Try the following usage of find:
find . -type d -exec sh -c 'cd "{}" && echo Do some stuff for {}, files are: $(ls *.*)' ';'
Use -maxdepth if you'd like to limit your directory levels.

Answer 3

You can do this using bash's subshell feature like so
for i in /tmp/test*; do
# don't do anything if there's no /test directory in /tmp
[ "$i" != "/tmp/test*" ] || continue
for j in $i/*.json; do
# don't do anything if there's nothing to run
[ "$j" != "$i/*.json" ] || continue
(cd $i && ./file_to_run)
done
done
When you wrap a command in ( and ) it starts a subshell to run the command. A subshell is exactly like starting another instance of bash except it's slightly more optimal.

Answer 4

You can also simply ask the shell to expand the directories/files you need, e.g. using command xargs:
echo /PROD/*/*.json | xargs -n 1 /tmp/test.py
or even using your original find command:
find /PROD/* -name "*.json" -exec /tmp/test.py {} \;
Both command will process all JSON files contained into any subdirectory of /PROD.

Answer 5

Another solution is to change slightly the Python code inside your script in order to accept and process multiple files.
For example, if your script contains something like:
def process(fname):
print 'Processing file', fname
if __name__ == '__main__':
import sys
process(sys.argv[1])
you could replace the last line with:
for fname in sys.argv[1:]:
process(fname)
After this simple modification, you can call your script this way:
/tmp/test.py /PROD/*/*.json
and have it process all the desired JSON files.