How can I run a command on all files with the extension .gz?

Often a command already accepts several files as arguments, e.g.

   1 zcat -- *.gz

On some systems, you would use gzcat instead of zcat. If neither is available, or if you don't care to play guessing games, just use gzip -dc instead.

The -- prevents a filename beginning with a hyphen from causing unexpected results.

If an explicit loop is desired, or if your command does not accept multiple filename arguments in one invocation, the for loop can be used:

   1 # Bourne
   2 for file in ./*.gz
   3 do
   4     echo "$file"
   5     # do something with "$file"
   6 done

To do it recursively, use find:

   1 # Bourne
   2 find . -name '*.gz' -type f -exec do-something {} \;

If you need to process the files inside your shell for some reason, then read the find results in a loop:

   1 # Bash
   2 while IFS= read -r file; do
   3     echo "Now processing $file"
   4     # do something fancy with "$file"
   5 done < <(find . -name '*.gz' -print)

This example uses ProcessSubstitution (see also FAQ #24), although a pipe may also be suitable in many cases. However, it does not correctly handle filenames that contain newlines. To handle arbitrary filenames, see FAQ #20.


BashFAQ/015 (last edited 2015-03-05 00:30:34 by izabera)