On Wednesday 07 December 2016 12:55, BartC wrote:
> But even Linux's 128KB will fill if someone wanted a command line that
> listed 20,000 files individually. But it would be spectacularly bad use
> of a command line interface which was designed for humans.
That's EXACTLY the point of having the shell do globbing.
I want to pass a whole lot of file names to some obscure command. I don't
remember how that command deals with metacharacters, but it doesn't matter: I
just say
command fooba?.jpg {here,there}/*.jpg another/place/*.{png,jpg} [a-z]/IMG*
and the shell expands the metacharacters ? {...} * [...] regardless of how much
smarts the command itself has.
There are thousands of programs I might use, and they may implement who knows
how many different globbing rules:
- some might support * and ? but not {...}
- some might support SQL-like % and _
- some might insist on regular expressions instead of globs
- some might support the full set of globbing metacharacters, but have bugs
- some might not support any metacharacters
- some might not support ** for recursive wildcards
Don't say "they'll all call a library to do it for them", because even if such
a library exists, its not necessarily the case that everyone will use it, or
*want* to use it. There are always those who insist on doing things their own
way, for their own reasons:
https://www.xkcd.com/1168/
https://explainxkcd.com/wiki/index.php/1168:_tar
I can't easily know in advance what globbing rules I can use for a particular
command, but I can know what rules my shell uses, and now *all* commands
support the same, whether they know it or not.
--
Steven
"Ever since I learned about confirmation bias, I've been seeing
it everywhere." - Jon Ronson
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