When you write a new program or shell script, you'll probably
want to be sure that its name doesn't conflict with any other commands on the
For instance, you might wonder whether there's a command named tscan
You can check by typing one of the commands in the following example.
If you get output (besides an error) from one of them, there's probably
already a command with the same name.
command works on ksh
and many Bourne shells;
I've shown it with a currency sign (