GNU bug report logs - #20767
seq: support multiple % in -f format

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Package: coreutils;

Reported by: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>

Date: Mon, 8 Jun 2015 02:07:02 UTC

Severity: wishlist

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Report forwarded to bug-coreutils <at> gnu.org:
bug#20767; Package coreutils. (Mon, 08 Jun 2015 02:07:03 GMT) Full text and rfc822 format available.
Acknowledgement sent to 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>:
New bug report received and forwarded. Copy sent to bug-coreutils <at> gnu.org. (Mon, 08 Jun 2015 02:07:03 GMT) Full text and rfc822 format available.

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

From: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
To: bug-coreutils <at> gnu.org
Subject: seq invocation limitations documentation
Date: Mon, 08 Jun 2015 07:28:25 +0800

On (info "(coreutils) seq invocation") perhaps mention if one needs to
use two % items, a for loop might be required,

$ for i in `seq 14484 10000 34484`; do printf %d=0x%x\\n $i $i; done
14484=0x3894
24484=0x5fa4
34484=0x86b4
Information forwarded to bug-coreutils <at> gnu.org:
bug#20767; Package coreutils. (Mon, 08 Jun 2015 09:10:03 GMT) Full text and rfc822 format available.

Message #8 received at 20767 <at> debbugs.gnu.org (full text, mbox):

From: Stephane Chazelas <stephane.chazelas <at> gmail.com>
To: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
Cc: 20767 <at> debbugs.gnu.org
Subject: Re: bug#20767: seq invocation limitations documentation
Date: Mon, 8 Jun 2015 10:09:33 +0100

2015-06-08 07:28:25 +0800, 積丹尼 Dan Jacobson:
> On (info "(coreutils) seq invocation") perhaps mention if one needs to
> use two % items, a for loop might be required,
> 
> $ for i in `seq 14484 10000 34484`; do printf %d=0x%x\\n $i $i; done
> 14484=0x3894
> 24484=0x5fa4
> 34484=0x86b4
[...]

Running several commands in sequence in a loop like that (and
storing the whole output of seq in memory) is not so good an
idea. At this point, it's probably better to use awk:

awk 'BEGIN{for (i = 14484; i <= 34484; i += 10000)
  printf "%d=0x%x\n", i, i}'

See also
https://unix.stackexchange.com/questions/169716/why-is-using-a-shell-loop-to-process-text-considered-bad-practice

Might be worth pointing out awk as a standard alternative to seq
for portability btw.

-- 
Stephane
Information forwarded to bug-coreutils <at> gnu.org:
bug#20767; Package coreutils. (Mon, 08 Jun 2015 15:10:03 GMT) Full text and rfc822 format available.

Message #11 received at 20767 <at> debbugs.gnu.org (full text, mbox):

From: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
To: Stephane Chazelas <stephane.chazelas <at> gmail.com>
Cc: 20767 <at> debbugs.gnu.org
Subject: Re: bug#20767: seq invocation limitations documentation
Date: Mon, 08 Jun 2015 23:08:53 +0800

Actually it would be great if one could just do
seq -f %d=0x%x 14484 10000 34484
where seq could just take the standard printf arguments, and % could be
used more than once, as I don't think it could mean any second argument...
Severity set to 'wishlist' from 'normal' Request was from Assaf Gordon <assafgordon <at> gmail.com> to control <at> debbugs.gnu.org. (Tue, 23 Oct 2018 02:27:01 GMT) Full text and rfc822 format available.
Changed bug title to 'seq: support multiple % in -f format' from 'seq invocation limitations documentation' Request was from Assaf Gordon <assafgordon <at> gmail.com> to control <at> debbugs.gnu.org. (Tue, 23 Oct 2018 02:27:01 GMT) Full text and rfc822 format available.
This bug report was last modified 6 years and 237 days ago.

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