silent 7za compression

Solution 1:

Yes that is possible.

Just add -y -bsp0 -bso0 to your command line. Those switches will disable progress, output reporting & assume yes answer to any possible questions, while still showing you any errors (which is perfect for cron usage).

Example:

7za a result.tar.7z -y -bsp0 -bso0 example.tar

From 7za --help:

-bs{o|e|p}{0|1|2} : set output stream for output/error/progress line
-y : assume Yes on all queries

Tested to work on 7z version: 16.02.

Note, that version 9.20 bundled with some older OS (you can check your version by running 7za i) doesn't support that feature. You can download latest statically linked binaries at the official website.

Solution 2:

Looking at the output of 7za --help, I don't think so.

Is there any particular reason why you don't want to just do 7za a archive.7z files > /dev/null?