Create 7zip archive from command line on Linux

To create the archive archive.7z from file source.txt:

7zr a archive.7z source.txt

To create the archive archive.7z from multiple files:

7zr a archive.7z file-1 file-2 file-3

To create a separate 7z archive for each .ogg file in current directory:

for i in `ls *.ogg`; do 7zr a $i.7z $i; done