a (Add) command
Adds files to archive.
Examples
7z a -tzip archive.zip subdir\
adds all files and subfolders from folder subdir to archive archive.zip.
7z a -t7z Files.7z *.txt -r
adds all *.txt files from current folder and its subfolders to archive Files.7z.
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)
-v (Volumes)
-w (Working Dir)
-x (Exclude)
See also
Commands:
d (Delete),
u (Update)
Switches:
-u (Update)