Currently errors get logged to stdout, they should get printed to stderr:

,----
| # 7za a foo.7z no_such_file > /dev/null
| # echo $?
| 1
| # 7za l foo.7z
|
| 7-Zip (A) 4.30 beta  Copyright (c) 1999-2005 Igor Pavlov  2005-11-18
| p7zip Version 4.30 (locale=en_US.UTF-8,Utf16=on,HugeFiles=on)
|
| Listing archive: foo.7z
|
|    Date      Time    Attr         Size   Compressed  Name
| ------------------- ----- ------------ ------------  ------------
| ------------------- ----- ------------ ------------  ------------
|                                                      0 files
`----


Also, please provide a quiet version which writes absolutely nothing
to stdout (and stderr) if everything is OK.  The verbose output makes
it hard to replace gzip/bzip2 in existing scripts.

forwarded 346463 my.p7zip@gmail.com
thanks dude

Upstream (Igor Pavlov) does not want to make different outputs for
messages, even though he's been asked several times to do so :(

I am tempted to suggest you use lzma, that is more like a gzip/bzip2
tool since the last version (4.43-2).

But I agree that it would be better to have a non verbose output by
default.

package p7zip p7zip-full
forcemerge 346463 772952
thanks

Sorry, I foolishly only consulted the p7zip-full bug listing, and thus
missed the duplicate.

...