Re: Checking for right # of args in a shell script (Was: a sed question)

In article <vk43n0$3gtg6$1@dont-email.me>,
Janis Papanagnou  <janis_papanagnou+ng@hotmail.com> wrote:
...

Agreed, in general, but in practice, the need rarely arises.

>
I certainly disagree on this; if you have 10..19 (or 100..199 etc.)
arguments the '<' test just doesn't trigger but '-lt' does. I mean,
why use a wrong operator. If it will only in specific cases produce
correct results, or if it produced in most cases correct results;
it's just the wrong thing.

We're not talking about the same thing.

 
The idiomatic way to do this is just:
 
    [ $# = 2 ] || usage()

>
Yes, but I don't use that but prefer (like you) [[...]], an in, say,

[ ] is easier in the simple cases.  But, whatever, either way is fine.

Also, when I need to do more complex arg verification, I use bash's [[ ]]
mechanism (Yes, I know OP is using /bin/sh, but there is no reason nowadays
not to use bash).

>
If the OP is on Linux the 'sh' might actually be a Bash. If he's,

I assume Linux unless/until I hear otherwise.  And I tend to also assume
some Debian-based Linux (again, unless/until ...).  In Debian-based
Linuxes, sh is "dash", which is pretty much a minimal
subset/POSIX-compliant version of the shell.  So, [[ ]] isn't available
there.

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