If you typed the above on the command line its wrong.
1) You shouldn't have "!" in the beginning.
2) You would need to have a space between "/bin/sh" and "/usr/local/bin/snort" if snort was a shell script.
3) You don't even need "/bin/sh" if "/usr/local/bin/snort" is executable (ls -l /usr/local/bin/snort to see permissions in the left most column - see "man chmod" for details on how to make a file executable.)
Your prompt ends in "#" so it may be you're thinking you need "#!/bin/sh" because you've seen that somewhere for shell scripts. In this case the "#" in your prompt is just a character and has no meaning. the "#!/bin/sh" syntax would need to appear as the first line of a script and tells the script to be interpreted using /bin/sh - this is common in scripts so that they run as expected if the user is not already using the same shell.