mass decompress gzip files without gz extension I have a massive number of files with extensions like `.0_1234` `.0_4213` and `.0_4132` etc. Some of these are `gzip` compressed and some are raw email. I need to determine which are compressed files, decompress those, and rename all files to a common extension once all compress files are decompressed. I've found I can use the file command to determine which are compressed, then grep the results and use `sed` to whittle the output down to a list of files, but can't determine how to decompress the seemingly random extensions. Here's what I have so far file *|grep gzip| sed -e 's/: .*$//g' I'd like to use `xargs` or something to take the list of files provided in output and either rename them to `.gz` so they can be decompressed, or simply decompress them in-line.

Don't use `gzip`, use `zcat` instead which doesn't expect an extension. You can do the whole thing in one go. Just try to `zcat` the file and, if that fails because it isn't compressed, `cat` it instead:


for f in *; do
( zcat "$f" || cat "$f" ) > temp &&
mv temp "$f".ext &&
rm "$f"
done


The script above will first try to `zcat` the file into `temp` and, if that fails (if the file isn't in gzip format), it will just `cat` it. This is run in a subshell to capture the output of whichever command runs and redirect it to a temp file (`temp`). Then, the `temp` is renamed to the original file name plus an extension (`.ext` in this example) and the original is deleted.