From: "Benjamin R. Haskell" <zsh@benizi.com>
To: Bart Schaefer <schaefer@brasslantern.com>
Cc: Zsh-Users List <zsh-users@zsh.org>
Subject: Re: virtual files?
Date: Fri, 22 Apr 2016 01:26:11 -0400 [thread overview]
Message-ID: <CAB2RFrQQ4K_1aS91zuMcY-LhTfeM0sHRfY0xOf+9q1QiQARHcA@mail.gmail.com> (raw)
In-Reply-To: <160420133446.ZM13832@torch.brasslantern.com>
[-- Attachment #1: Type: text/plain, Size: 1547 bytes --]
On Wed, Apr 20, 2016 at 4:34 PM, Bart Schaefer <schaefer@brasslantern.com>
wrote:
> On Apr 19, 11:32pm, Benjamin R. Haskell wrote:
> }
> } Using the `=()` substitution ZyX mentions:
> }
> } () {
> } local tmp=$1
> } wget -q $link -O $tmp
> } echo -n \$
> } grep \"answer\" $tmp | cut -d \$ -f 2 | cut -d \< -f 1
> } } =(:)
> }
> } The '() { ... }' construct is an anonymous function, just for controlling
> } the scope of the temporary file, and for passing it in as a positional
> } parameter. It has the disadvantage that it won't remove the tmp file if
> } something goes wrong.
>
> In fact the point of using =(:) is that it WILL remove the tmp file if
> something goes wrong (unless it's something completely catastrophic like
> the shell itself crashing, but in that case an explicit "rm" wouldn't
> work either).
>
Right, it's the "unless" I'm worried about:
## temp file isn't deleted on exit, so it's still there to be removed
$ ( () { local tmp=$1 ; echo $tmp ; exit 1 } =(:) ) | xargs rm --verbose
removed '/tmp/zsh9OzJL1'
## temp file is deleted with exit trap
$ ( () { local tmp=$1 ; trap "rm $tmp" INT QUIT EXIT ; echo $tmp ; exit 1 }
=(:) ) | xargs rm --verbose
rm: cannot remove '/tmp/zshhzsFQo': No such file or directory
Instead of exit traps, you can use "always" blocks:
>
> () {
> local tmp=$1;
> {
> : do stuff with $tmp
> exit
> } always {
> rm $tmp
> }
> } =(:)
>
Cool! ~Half my scripts have no need of POSIX-ness, so that'll come in
handy.
--
Best,
Ben
next prev parent reply other threads:[~2016-04-22 5:26 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-20 1:00 Emanuel Berg
2016-04-20 1:27 ` Nikolay Aleksandrovich Pavlov (ZyX)
2016-04-20 2:12 ` Emanuel Berg
2016-04-20 2:31 ` Nikolay Aleksandrovich Pavlov (ZyX)
2016-04-20 4:03 ` Bart Schaefer
2016-04-20 6:06 ` Emanuel Berg
2016-04-21 22:14 ` Emanuel Berg
2016-04-22 1:08 ` Bart Schaefer
2016-04-20 3:32 ` Benjamin R. Haskell
2016-04-20 20:34 ` Bart Schaefer
2016-04-22 5:26 ` Benjamin R. Haskell [this message]
2016-04-21 4:12 ` Emanuel Berg
2016-04-21 6:58 ` Bart Schaefer
2016-04-21 8:05 ` Emanuel Berg
2016-04-22 5:55 ` Benjamin R. Haskell
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