[userbinator]

It's like the opposite of && (continue until one alternative is false), for if you want to continue with alternatives in sequence until one alternative becomes true: a || b || c || ...

This usage is commonly found in other places than the shell, like JavaScript, Perl, and PHP.

[deafbybeheading]

Thanks, I know `||` in general--I meant I hadn't seen the specific construction GP had used. The error handling to delete the output file in case the command failed is really elegant.

[peff]

It's actually a little dangerous; what happens when you hit "^C" and the process dies before getting a chance to clean up? It's safer to do:

  some_cmd >foo.tmp && mv foo.tmp foo

The mv will do an atomic rename(), so that you either get the fully formed contents, or nothing at all.

[deafbybeheading]

Only if you interrupt the actual `rm`, no? If you interrupt the main command, you won't get a 0 exit code so the `||` branch still executes.

Your mechanism is clearly safer, but the user is required to clean up `foo.tmp` themselves in case of failure, so it's not really comparable.