u (Update) command

Update older files in the archive and add files that are not already in the archive.

Note: The current version of 7-Zip cannot change an archive which was created with the solid option switched on. To update a .7z archive you must create and update that archive only in non-solid mode (-ms=off switch).

Example

7z u archive.zip *.doc

updates *.doc files to archive archive.zip.

Switches that can be used with this command

-i (Include) -m (Method)
-p (Set Password)
-r (Recurse)
-sfx (create SFX)
-si (use StdIn)
-so (use StdOut)
-ssw (Compress shared files)
-t (Type of archive)
-u (Update)
-w (Working Dir)
-x (Exclude)

See also

Commands: a (Add), d (Delete),

Switches: -u (Update)