How to loop through a directory recursively to delete files with certain extensions

As a followup to mouviciel's answer, you could also do this as a for loop, instead of using xargs. I often find xargs cumbersome, especially if I need to do something more complicated in each iteration.

for f in $(find /tmp -name '*.pdf' -or -name '*.doc'); do rm $f; done

As a number of people have commented, this will fail if there are spaces in filenames. You can work around this by temporarily setting the IFS (internal field seperator) to the newline character. This also fails if there are wildcard characters \[?* in the file names. You can work around that by temporarily disabling wildcard expansion (globbing).

IFS=$'\n'; set -f
for f in $(find /tmp -name '*.pdf' -or -name '*.doc'); do rm "$f"; done
unset IFS; set +f

If you have newlines in your filenames, then that won't work either. You're better off with an xargs based solution:

find /tmp \( -name '*.pdf' -or -name '*.doc' \) -print0 | xargs -0 rm

(The escaped brackets are required here to have the -print0 apply to both or clauses.)

GNU and *BSD find also has a -delete action, which would look like this:

find /tmp \( -name '*.pdf' -or -name '*.doc' \) -delete

find is just made for that.

find /tmp -name '*.pdf' -or -name '*.doc' | xargs rm

Without find:

for f in /tmp/* tmp/**/* ; do
  ...
done;

/tmp/* are files in dir and /tmp/**/* are files in subfolders. It is possible that you have to enable globstar option (shopt -s globstar). So for the question the code should look like this:

shopt -s globstar
for f in /tmp/*.pdf /tmp/*.doc tmp/**/*.pdf tmp/**/*.doc ; do
  rm "$f"
done

Note that this requires bash ≥4.0 (or zsh without shopt -s globstar, or ksh with set -o globstar instead of shopt -s globstar). Furthermore, in bash <4.3, this traverses symbolic links to directories as well as directories, which is usually not desirable.