Recursively read folders and executes command on each of them

Question

I am trying to recurse into folders and then run commands on them, using bash script. Any suggestions?

Answer 1

If you want to recurse into directories, executing a command on each file found in those, I would use the find command, instead of writing anything using shell-script, I think.

That command can receive lots of parameters, like type to filter the types of files returned, or exec to execute a command on each result.

For instance, to find directories that are under the one I'm currently in :

find . -type d -exec echo "Hello, '{}'" \;

Which will get me somehthing like :

Hello, '.'
Hello, './.libs'
Hello, './include'
Hello, './autom4te.cache'
Hello, './build'
Hello, './modules'

Same to find the files under the current directory :

find . -type f -exec echo "Hello, '{}'" \;

which will get me something like this :

Hello, './config.guess'
Hello, './config.sub'
Hello, './.libs/memcache_session.o'
Hello, './.libs/memcache_standard_hash.o'
Hello, './.libs/memcache_consistent_hash.o'
Hello, './.libs/memcache.so'
Hello, './.libs/memcache.lai'
Hello, './.libs/memcache.o'
Hello, './.libs/memcache_queue.o'
Hello, './install-sh'
Hello, './config.h.in'
Hello, './php_memcache.h'
...

Some would say "it's not shell"... But why re-invent the wheel ?
(And, in a way, it is shell ^^ )

For more informations, you can take a look at :

• man find
• lots of tutorials found with google, like, for instance, Unix Find Command Tutorial

Answer 2

Bash 4.0 introduced the globstar option, so a construct like:

for f in mydir/**/*
do
  # operations here
done

...will act recursively on whatever lands in $f. Turn this on with "shopt -s globstar", otherwise the ** will be treated as a singular *.

Found this gem today at http://www.linuxjournal.com/content/globstar-new-bash-globbing-option, after being inspired by the zsh construct (which I have enabled by default).

Answer 3

Some basic shells miss commands like 'find' and some of their commands don't support recursivity. In that case you can use this script to run the desired command in all subdirs in the tree:

CDIR=$(pwd)
for i in $(ls -R | grep :); do
    DIR=${i%:}                    # Strip ':'
    cd $DIR
    $1                            # Your command
    cd $CDIR
done

If you name the above "recurse.sh" then use:

./recurse.sh <command>

Example (change the owner/group to 'root' of all files in the tree):

./recurse.sh "chown 0:0 *"