Some files that you download will come with a .sfv file.
This is used to verify that the files that you received are the same as
the originals.

cksfv (Check SFV) is a program that can use the .sfv file to verify the
downloaded files. Also, it can be used to create new .sfv files.

cksfv is a command line tool that uses crc32 checksum to verify file 
integrity. .sfv is simple file verification. 

There is a script to integrate this tool with GNOME's Nautilus file manager, 
but since GNOME isn't included in Slackware, it is included as part of the 
documentation instead of in the normal location.  You can install it on your
own or modify the SlackBuild script to do so.  It can be found under the
"./scripts" directory of the source code, and is called CheckSFV in the
resulting package's documentation directory.  All you need to do is to copy 
the "CheckSFV" file to $HOME/.gnome2/nautilus-scripts