Exit Codes from 7-Zip

7-Zip returns the following exit codes:

Code	Meaning
0	No error
1	Warning (Non fatal error(s)). For example, one or more files were locked by some other application, so they were not compressed.
2	Fatal error
7	Command line error
8	Not enough memory for operation
255	User stopped the process

Notes from this site

Not part of the 7-Zip manual. Written by this site; examples checked with 7-Zip 26.04.

How do I check the exit code in a script?

The official Linux and macOS console binary is 7zz. Treat 0 as success, 1 as "finished, but read the log", and 2 or higher as failure.

7zz a backup.7z data/
rc=$?
if [ "$rc" -gt 1 ]; then
  echo "7-Zip failed with code $rc" >&2
  exit "$rc"
fi
7zz t backup.7z || exit 1
# under set -e, accept warnings (code 1) but stop on anything worse:
7zz a backup.7z data/ || [ $? -eq 1 ]

With set -e a code 1 would otherwise abort the script, which is why the last line allows it. The t line tests the archive after writing it; see t (Test).

What do the exit codes mean? (tested on macOS)

Code	Seen when
0	Success.
1	An input file was missing or unreadable (`7zz a x.7z nofile`). The archive may be incomplete.
2	Wrong password, a truncated or non-archive file, a missing archive, or updating a `.tar.gz` in place.
7	A mistyped switch or command, such as `-bogus`.
8	Not enough memory (from the vendor table; not reproduced here). See the dictionary size option of -m.
255	The user stopped the process. It also appears when a prompt got no answer because input was closed. Add -y or -ao.

Which file caused code 1?

The warning goes to standard error and names the file, so 7zz a x.7z data/ 2>err.log keeps it for later (an unreadable file gave data/locked.txt : errno=13 : Permission denied). It is also repeated in a "WARNINGS" list at the end of the normal output. -bso0 -bsp0 silences normal output and progress but not this warning. See -bs to redirect output streams.

Common mistake

Testing only for non-zero: a locked or unreadable file gives code 1 even though the rest of the archive was written. Log the warning and review it instead of retrying blindly.