From: Shineru <theshinneru@gmail.com>
To: Shineru <theshinneru@gmail.com>, zsh-workers@zsh.org
Subject: Re: tr [:lower:]
Date: Thu, 2 Sep 2021 00:53:33 +1000 [thread overview]
Message-ID: <CAKik2npP0AgFarp8Ac1VecfNtujd-jB9hNLjjvAqW1v1T-hFmw@mail.gmail.com> (raw)
In-Reply-To: <YS2IQ96Qg0pYU5Ra@fullerene.field.pennock-tech.net>
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Thanks!
вт, 31 авг. 2021 г. в 11:39, Phil Pennock <
zsh-workers+phil.pennock@spodhuis.org>:
> On 2021-08-31 at 11:04 +1000, Shineru wrote:
> > zsh 5.8.1. Arch GNU/Linux
> >
> > zsh: echo "hello" | tr [:lower:] [:upper:]
> > zsh: no matches found: [:lower:]
>
> setopt nonomatch
> or: unsetopt nomatch
> but: both of these are dangerous, because there's a real quoting issue
> here.
>
> % touch l p
> % echo "hello" | tr [:lower:] [:upper:]
> heppo
> bash$ echo "hello" | tr [:lower:] [:upper:]
> heppo
>
> Without quoting,
> [:lower:] matches any of: l o w e r :
> [:upper:] matches any of: u p e r :
> so the globbing turns the pipeline into:
> echo "hello" | tr "l" "p"
>
> By default, zsh complains about unmatched patterns, rather than letting
> them fall through silently. Falling through leads to this sort of
> "foot-gun" construct, where shells encourage you to do something which
> "only works as long as X is not true", instead of having reliable code.
>
> So you want, for safety, in any shell which resembles POSIX at all:
>
> echo 'hello' | tr '[:lower:]' '[:upper:]'
>
> (This probably belongs on zsh-users.)
>
> -Phil
>
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prev parent reply other threads:[~2021-09-01 14:54 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-31 1:04 Shineru
2021-08-31 1:39 ` Phil Pennock
2021-09-01 14:53 ` Shineru [this message]
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