The C Shell repeat Command

The C shell has a built-in command that lets you execute a command repeatedly:

% repeat n command

All you do is specify the number of repetitions, followed by the command you want to re-execute. A trivial example would be:

% repeat 4 echo Enter name: Enter name: Enter name: Enter name: Enter name:

Simple, right? Just imagine what Jack Nicholson could have done in the movie The Shining if he had traded in his typewriter for a UNIX system:

% repeat 500 echo "All work and no play makes Jack a dull boy."

Ok, this is fun at first, but you may soon wonder whether this command has any down-to-earth uses. It does, and I'll conclude with some more useful examples:

1. Print three copies of memo:
   
   

   % repeat 3 pr memo | lp
   

   
   
   
2. Run popd () four times to clear a directory stack:
   
   

   % repeat 4 popd
   

   
   
   
3. Append 50 boilerplate files to report:
   
   

   % repeat 50 cat template >> report
   

   
   
   

Some versions of the C shell repeat command have a quoting bug. See the end of article .

- DG