execute command from find called by find

Question

Is there a way to call find recursively?

I would like to search for files matching a given pattern only in directories matching another pattern.

Basically:

for each (sub)directory D matching "*.data"
do
  for each file F in directory D (with subdirs) matching "*.important.txt"
  do
    run command foo on F
  done
done

Now, if I leave out the innermost requirement (run command foo in F), it is pretty simple:

find . -type d -name "*.data" \
     -exec find \{\} -type f -name "*.important.txt" \;

However, I haven't found a way to pass a command to the inner find. E.g. the following prints out find: missing argument to `-exec' each time the inner find is called:

 find . -type d -name "*.data" \
      -exec find \{\} -type f -name "*.important.txt" \
                 -exec "foo \{\} \;" \;

Any solution should be posix compliant (runnable within a /bin/sh script), esp. I am not looking for solutions that

• wrap the inner find into a separate shell-script
• wrap the inner find into a bash-function

Answer 1

To run find on its own result, you can use the -c argument to sh (or bash) to prevent the outer find command from treating the inner {} specially. However, you then need to pass the result from the outer find as an argument to sh, which can be expanded with $0:

find . -type d -name "*.data" \
      -exec sh -c 'find "$0" -type f -name "*.important.txt" -exec echo \{\} \;' \{\} \;

Note: $0 should be quoted ("$0") to prevent issues with directory names containing whitespace.

This is not really a "recursive" solution, because it doesn't allow arbitrarily deep nesting without some hairy escaping, but it does support the two levels of find -execs you asked for in your example.

If your example is similar to your actual problem, you might also experiment with the -path argument to find instead:

find . -path '*.data/*important.txt'

Answer 2

bash version (not POSIX compliant)

#!/bin/bash
find . -type d -name 'a *' -print0 \
    | while IFS= read -r -d '' dir ; do
        find "$dir" -type f -name "*.c" -exec echo \{\} \;
    done

Problems:

• read has no -d parameter in POSIX
• find has no -print0 parameter in POSIX

---

(bad) sh version (POSIX compliant)

#!/bin/sh
# WARNING: while this will work on directory names with spaces,
#          it will break on directory names that contain newlines
find . -type d -name 'a *' -print \
    | while IFS= read -r dir ; do
        find "$dir" -type f -name "*.c" -exec echo \{\} \;
    done

Problem: As stated in the comment, it will break on directory names containing newlines. You may think this is not a realistic issue, but this adds unnecessary fragility to your script. Maybe another program has a bug that will create such a directory, etc.

---

(better) sh version

see Ian Robertson's answer

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Btw. if you need your scripts to be POSIX compliant, it's a good idea to use shellcheck. For example, it will notice that read -d is not defined in POSIX.