Tuesday Tiny Techie Tip

Alias override

This works great until you have a whole bunch of files that you really really really want to delete. Then, bouncing on the "y" and return keys gets kind of old.

There are a number of ways to temporarily get around an aliased command. I'll save the best for last.

• You can cancel the alias altogether:

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  % unalias rm
  % rm foo*
  

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  The problem with this approach is that when you've finished deleting the offensive files the alias is still gone, so you're back to where you can accidentally delete things for the life of that shell.

• You can qualify the command by using the full path:

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  % /bin/rm foo*
  

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  Of course you have to know where the command lives in order to do this. And which(1) won't help because it will report the alias itself.

• You could pipe yes(1) to the command:

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  % yes | rm foo*
  

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  yes is a command that by default says "y" until the cows come home. If you give it an argument like "yes 'go away'" it will say "go away" until the cows come home. Try it out. It's a cute hack to get around programs that insist on asking the same question over and over again even though you know the answer is always the same.

• The right answer: By prefacing an aliased command with a backslash "\", you override the alias value for the command (and instead search through your path) for that single execution:

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  % \rm foo*
  % rm bar
  rm: remove bar? n
  

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