Using md5sum

[alex <radsky@ncia.net>]

I don't remember the source of the following instructions that I 
have in my notes.

"To use these things* you use the linux program [b]md5sum[/b]. type 
[b]md5sum [i]filename[/i][/b] to create a checksum. You can channel 
the output to a different file if you want with the > operator. To 
check a file use [b]md5sum --check [i]checksumfile.md5[/i][/b]."

things* - factors considered when creating a md5sum checksum.

Would someone please elaborate on the steps described in the quote
starting with "you use the linux program [b]md5sum[/b]"?
How do you 'use' [b]md5sum[/b]...........?