explanation of the script:
b=./B reference a file, "B" in current dir "./"
tail throw the end of a file to the screen -n specify the number of lines +3 from 3rd line to end
$0 specify the file, $0 = this one, the bash script.
| redirect output as input to the next command
zcat decompress data, no param= from stdin to stdout
>$b take stdout and redirect it to the file b (./B)
$b execute that file as a command/program
rm $b remove that file
exit quit that script (so it doesn't try to exec something like ?gz%?#45afg45[...]