Re: Bug#1075768: coreutils: ls doesn't honour COLUMNS if writing to a teletype

[Pádraig Brady]

On 04/07/2024 17:29, наб wrote:
> Package: coreutils
> Version: 9.1-1
> Version: 9.4-3
> Severity: normal
>
> Dear Maintainer,
>
> Quoth POSIX.1-2024:
> 103406  ENVIRONMENT VARIABLES
> 103407  The following environment variables shall affect the execution of ls:
> 103408  COLUMNS  Override the system-selected horizontal display line size, 
> used to determine the
> 103409           column position width for writing multiple text-column output. 
> See XBD Chapter
> 103410           8 (on page 167) for valid values and results when it is unset 
> or null. The ls utility
> 103411           shall use this value to calculate how many pathname text 
> columns to write (see
> 103412           −C). The column width chosen to write the names of files in 
> any given directory
> 103413           shall be constant. Filenames shall not be truncated to fit 
> into the multiple text-
> 103414           column output.
>
> Quoth UNIX™ System V ‒ Release 2.0 User Reference Manual, DEC™ Processors 
> (1984):
>    There are three major listing formats.  The default format is to list one 
> entry
>    per line, the -C and -x options enable multi-column formats, and the -m
>    option enables stream output format in which files are listed across the 
> page,
>    separated by commas.  In order to determine output formats for the -C, -x,
>    and -m options, /s uses an environment variable, COLUMNS, to determine the
>    number of character positions available on one output line.  If this 
> variable is
>    not set, the terminfo database is used to determine the number of columns,
>    based on the environment variable TERM.  If this information cannot be
>    obtained, 80 columns are assumed.

Right, both POSIX 2003 and 2008 say that COLUMNS should override any auto width 
determination.
However since the beginning, GNU ls has the -w option to override the width,
and so leaves $COLUMNS as something that is auto set (and usually is by the 
shell).
Since changing this to align with POSIX adds no new functionality,
I'm reluctant to adjust this at this stage, in case COLUMNS is set
incorrectly / inadvertently for some users.
We could safely change this I suppose, gated with the POSIXLY_CORRECT env var.

cheers,
Pádraig.