precompressing and ownership - UNIX for Dummies Questions & Answers

dheian · #1 08-13-2008

I'm looking for a way to create preprocessed .gz files of static pages to serve up to those browsers that can accept them.

I know I can use:
gzip -c --best index.html > index.html.gz

to create the .gz file _and_ keep the original.

What's the proper command line way to run that on each index.html file in all the subdirectories? There's a way via find and/or xargs, right? Can it be done from the command line, or do I need a script?

Also, if I run the cron as a user other than root (i.e. my apache user) will the resulting gzip be owned by apache or do I have to chown it?

Thanks for any advice!

era · #2 08-13-2008

Scripts are just canned command lines; if you can run it from the command line, you can put it in a script, and vice versa.

I believe gzip will preserve ownership of files but you can't use the -c option and redirection then. Of course, the user running the script will need write access to the files and directories you want to modify in any event.

Code:

find /path/to/var/www/html-docs/whatever -name 'index.html' -exec gzip -9 {} \;

To keep the originals as well, something a bit more complex is called for. The new files will be owned by the user who created them, and their permissions will be controlled by the user's umask.

Code:

find /path/to/var/www/html-docs/whatever -name 'index.html' -print |
xargs -n 1 -i sh -c 'gzip -c -9 < {} >{}.gz'

The sh is needed here because that's what handles redirection. Equivalently, you could create put those commands in a small script, and run that from xargs or find -exec on each file in turn. Here's an example.

Code:

#!/bin/sh
gzip -c -9 <"$1" >"$1".gz

Here's a slightly more elaborate script which handles multiple files and sets the permissions and ownership of the new files. Still, you could put those same commands in the arguments to sh -c if you don't want to create a physical script file for some reason.

Code:

#!/bin/sh
for f; do
  gzip -c -9 <"$f" >"$f".gz
  chmod 644 "$f".gz
  chown www-data:www-data "$f".gz
done

Now if you had saved this in $HOME/zipper (and chmod +x of course) you could run

Code:

find /path/to/var/www/html-docs/whatever -name 'index.html' -print | xargs $HOME/zipper

dheian · #3 08-13-2008

Thank you so much! It worked great.

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