Re: bin/59896: tr extends string2 incorrectly when [#*0] is specified

["RVP via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR bin/59896; it has been noted by GNATS.

From: RVP <rvp%SDF.ORG@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: bin/59896: tr extends string2 incorrectly when [#*0] is
 specified
Date: Sat, 10 Jan 2026 07:32:51 +0000 (UTC)

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 On Wed, 7 Jan 2026, jarle.greipsland%norid.no@localhost via gnats wrote:
 
 > NetBSD tr:
 > $ echo A N Y | tr A-Z 'a-c[q*20]x-z'
 > a q y
 > which is the expected output.
 >
 > $ echo A N Y | tr A-Z 'a-c[q*0]x-z'
 > a q q
 > should have been equivalent to the first expression, but it isn't.
 >
 > The man page states:
 > ... If n is omitted or is zero, it is interpreted as
 >    large enough to extend the string2 sequence to the length of
 >    string1.  If n has a leading zero, it is interpreted as an
 >    octal value; otherwise, it is interpreted as a decimal
 >    value.
 >
 
 It seems to me that this says `[q*]' will extend `string2' to the remaining
 length of `string1' first, then `x-z' will get tacked on, exceeding len. of
 `string1', and therefore will not be used.
 
 > It seems like NetBSD's tr does not take into account any characters
 > in string2 found after the [#*n] expression.
 >
 
 But, should it?
 
 > GNU tr from coreutils behaves as I would expect:
 > $ echo A N Y | gtr A-Z 'a-c[q*20]x-z'
 > a q y
 > $ echo A N Y | gtr A-Z 'a-c[q*0]x-z'
 > a q y
 >
 
 GNU tr(1) seems to be the only one which does this. Both OpenBSD and FreeBSD
 tr behave like NetBSD's; as does the tr in OpenIndiana 2025.10.
 
 -RVP
 
 PS. I like what GNU tr(1) does, but, I'd like clarification on this first,
 vis-à-vis POSIX and historical behaviour. :)
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