GNU bug report logs - #62144
Unexpected output

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: walonen <walonen <at> gmx.net>
To: bug-sed <at> gnu.org
Subject: Unexpected output
Date: Sun, 12 Mar 2023 09:05:37 +0100

[Message part 1 (text/plain, inline)]

Hello,
I have found an unexpected behavior of sed. I would expect the same
output for the following commands:

sed '/root/!d' /etc/passwd
sed '/root/{ !d }' /etc/passwd

$ sed --version
sed (GNU sed) 4.7
Packaged by Debian
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
<https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by Jay Fenlason, Tom Lord, Ken Pizzini,
Paolo Bonzini, Jim Meyering, and Assaf Gordon.
GNU sed home page: <https://www.gnu.org/software/sed/>.
General help using GNU software: <https://www.gnu.org/gethelp/>.
Fehlerberichte bitte per E-Mail (auf englisch) an: <bug-sed <at> gnu.org>.



Seen ouotput:

$ sed '/root/!d' /etc/passwd
root:x:0:0:root:/root:/bin/bash

$ sed '/root/{ !d }' /etc/passwd
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
... the whole file

BR,
Stefan Scheruebl

[Message part 2 (text/html, inline)]

Message #10 received at 62144-done <at> debbugs.gnu.org (full text, mbox):

From: Jim Meyering <jim <at> meyering.net>
To: walonen <walonen <at> gmx.net>
Cc: 62144-done <at> debbugs.gnu.org
Subject: Re: bug#62144: Unexpected output
Date: Tue, 14 Mar 2023 09:24:28 -0700

tags 62144 notabug
stop

On Sun, Mar 12, 2023 at 7:24 AM walonen <walonen <at> gmx.net> wrote:
> I have found an unexpected behavior of sed. I would expect the same
> output for the following commands:
>
> sed '/root/!d' /etc/passwd
> sed '/root/{ !d }' /etc/passwd

Thanks for the report, but the '!' modifier must be applied to an
address specification, so your latter command should be spelled like
this:

sed '/root/!{ d }' /etc/passwd

and that is equivalent to the first one.

Quoting the info documentation on this topic:

   Appending the '!' character to the end of an address specification
(before the command letter) negates the sense of the match.  That is, if
the '!' character follows an address or an address range, then only
lines which do _not_ match the addresses will be selected.  The
following command replaces the word 'hello' with 'world' only in lines
_not_ containing the word 'apple':

     sed '/apple/!s/hello/world/' input.txt > output.txt

   The following command replaces the word 'hello' with 'world' only in
lines 1 to 3 and 18 till the last line of the input file (i.e.
excluding lines 4 to 17):

     sed '4,17!s/hello/world/' input.txt > output.txt

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