Why don't you just type:
In the terminal.
The shell will say somehing like
seacrhstr: command not found
Ok, I take the downvote, because the answer is stupid, I just want to know: What's wrong with this answer!!! The asker said:
and see if a command is available.
Typing the command will tell you if it is available!.
Probably he/she meant "with out executing the command" or "to include it in a script" but I cannot read his mind ( is not that I can't regularly it is just that he's wearing a
mind reading deflector )