[Help-bash] procps output truncated due to bash setting $COLUMNS

[jengelh]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc -I/home/abuild/rpmbuild/BUILD/bash-4.2 
-L/home/abuild/rpmbuild/BUILD/bash-4.2/../readline-6.2
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-suse-linux-gnu' 
-DCONF_VENDOR='suse' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL 
-DHAVE_CONFIG_H   -I.  -I. -I./include -I./lib   -fmessage-length=0 -O2 -Wall 
-D_FORTIFY_SOURCE=2 -fstack-protector -funwind-tables 
-fasynchronous-unwind-tables -g  -D_GNU_SOURCE -DRECYCLES_PIDS -Wall -g 
-std=gnu89 -Wuninitialized -Wextra -Wno-unprototyped-calls -Wno-switch-enum 
-Wno-unused-variable -Wno-unused-parameter -ftree-loop-linear -pipe 
-fprofile-use
uname output: Linux ares07 3.4.18-jng6-default #1 SMP Wed Nov 14 17:04:47 UTC 
2012 (21e90c1) x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-suse-linux-gnu

Bash Version: 4.2
Patch Level: 24
Release Status: release

Description:
        procps-3.3.3 and later versions truncate their output at $COLUMN
        columns, for example when executing `ps | less -S`.
        The logic procps uses is, in this order, quoted from the source:

        // 1. Defaults are implementation-specific. (ioctl,termcap,guess)
        // 2. COLUMNS and LINES override the defaults. (standards compliance)
        // 3. Command line options override everything else.
        // 4. Actual output may be more if the above is too narrow.

        This sounds reasonable. What makes it awkward is that bash *always*
        has $COLUMNS set. That looks like an undesired feature to me.

        tcsh for example does not set $COLUMNS on its own.

        The question here is: should bash not set $COLUMNS, or should ps
        ignore $COLUMNS if not outputting to a tty, or something else?

Repeat-By:
        ps | less

        Observe how one does not get more than $COLUMNS worth of output,
        even though ps's stdout is not a tty.

Fix:
        My proposed "fix" is to turn off automatic setting of $COLUMNS -
        or at least to not export it if it was automatically set.