[Bug 1329059] New: Don't produce terminal control sequences in perldoc

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1329059

            Bug ID: 1329059
           Summary: Don't produce terminal control sequences in perldoc
           Product: Fedora
           Version: rawhide
         Component: perl-Pod-Perldoc
          Keywords: FutureFeature, Reopened
          Assignee: ppisar(a)redhat.com
          Reporter: praiskup(a)redhat.com
        QA Contact: extras-qa(a)fedoraproject.org
                CC: extras-qa(a)fedoraproject.org, hhorak(a)redhat.com,
                    jmlich83(a)gmail.com, mmaslano(a)redhat.com,
                    perl-devel(a)lists.fedoraproject.org, ppisar(a)redhat.com,
                    ToddAndMargo(a)zoho.com
        Depends On: 1258741



+++ This bug was initially created as a clone of Bug #1258741 +++

Short summary, command 'PAGER=less perldoc perlreref' behaves oddly.

The issue is that perldoc *always* produces some terminal (color?) sequences,
and less (by default) is careful to escape terminal sequences rather then
printing them in a raw form.

This bug is here to ask whether it is possible (or makes sense) to not produce
terminal sequences in perldoc output.  Or simply request for brainstorm.

See the original bug report for more info.


Referenced Bugs:

https://bugzilla.redhat.com/show_bug.cgi?id=1258741
[Bug 1258741] "PAGER=less perldoc perlreref" escapes color sequences, drop
them or interpret them
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[Bug 1329059] Don't produce terminal control sequences in perldoc

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1329059

Petr Pisar <ppisar(a)redhat.com&gt; changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |CLOSED
         Resolution|---                         |WORKSFORME
        Last Closed|                            |2016-04-21 02:28:49



--- Comment #1 from Petr Pisar <ppisar(a)redhat.com&gt; ---
I cannot reproduce it on Fedora 23:

TERM=xterm
LESSOPEN=|/usr/bin/lesspipe.sh %s
ncurses-5.9-21.20150214.fc23.x86_64
ncurses-libs-5.9-21.20150214.fc23.x86_64
xterm-318-2.fc23.x86_64
less-481-1.fc23.x86_64
perl-Pod-Perldoc-3.25-347.fc23.noarch

Though I admit some people sometimes complained about the same issue. I would
welcome reliable reproducer.

To the question: Yes, perldoc has "-t" argument that disables ANSI sequences on
the output. I think "perldoc --help" is not so hard way to discover it.

I can fairly reproduce it with "perldoc -T perlreref | less".  The capital -T
prints the output to stdout instead of sending it to a pager. But the perldoc
(that I have, the behavior changes with various perldoc versions) feeds the
pager from a temporary file. strace shows:

[pid  3367] execve("/usr/bin/less", ["less"],
["XDG_VTNR=1",
"XDG_SESSION_ID=1", "SSH_AGENT_PID=2103",
"HOSTNAME=dhcp-0-146.brq.redhat.c"..., "SHELL=/bin/bash",
"TERM=xterm",
"HISTSIZE=1000", "TERMPATH=/home/petr/.termcap:/et"...,
"WINDOWID=65011747",
"QTDIR=/usr/lib64/qt-3.3", "QTINC=/usr/lib64/qt-3.3/include",
"XORG_RUN_AS_USER_OK=1", "USER=petr",
"XTERM_SHELL=/bin/bash",
"LS_COLORS=rs=0:di=01;34:ln=01;36"...,
"SSH_AUTH_SOCK=/tmp/ssh-QUjk3MkTh"...,
"PAGER=less", "PATH=/home/petr/bin:/usr/lib64/q"...,
"MAIL=/var/spool/mail/petr", "_=/usr/bin/less",
"QT_IM_MODULE=xim",
"PWD=/home/petr", "XMODIFIERS=@im=SCIM",
"EDITOR=/usr/bin/vim",
"LANG=cs_CZ.UTF-8", "MODULEPATH=/etc/scl/modulefiles:"...,
"LOADEDMODULES=",
"HISTCONTROL=ignoredups", "XTERM_VERSION=XTerm(318)",
"XTERM_LOCALE=cs_CZ.UTF-8", "HOME=/home/petr",
"XDG_SEAT=seat0", "SHLVL=5",
"LESS=-R", "LOGNAME=petr", "CVS_RSH=ssh",
"QTLIB=/usr/lib64/qt-3.3/lib",
"MODULESHOME=/usr/share/Modules", "LESSOPEN=|/usr/bin/lesspipe.sh
%"...,
"WINDOWPATH=1", "XDG_RUNTIME_DIR=/run/user/500",
"DISPLAY=:0.0",
"GTK_IM_MODULE=scim", "XAUTHORITY=/home/petr/.Xauthorit"...,
"CCACHE_HASHDIR=",
"BASH_FUNC_module()=() {  eval `/"..., "BASH_FUNC_scl()=() {  local
CMD="...])
= 0

I suspect perldoc sets LESS=-R. I dont' have the variable in my environment:

$ set |grep LESS
LESSOPEN='|/usr/bin/lesspipe.sh %s'

"perldoc -T perlreref | LESS=-R less" works for me.

From my point of view, perldoc is fine in Fedora. This is issue in RHEL-7's
perldoc.

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[Bug 1329059] Don't produce terminal control sequences in perldoc

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1329059



--- Comment #2 from Petr Pisar <ppisar(a)redhat.com&gt; ---
Actually I cannot reproduce it in RHEL-7 either. Thought it works there
probably for some other reason. If you want to open a bug for RHEL-7, I need
the reproducer.

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[Bug 1329059] Don't produce terminal control sequences in perldoc

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1329059



--- Comment #3 from Pavel Raiskup <praiskup(a)redhat.com&gt; ---
(In reply to Petr Pisar from comment #1)
>  I cannot reproduce it on Fedora 23: 
I feel I'm facing some magic, because I'm not able to reproduce this on F23
neither, *now*.

>  To the question: Yes, perldoc has "-t" argument that
> disables ANSI sequences
>  on the output. I think "perldoc --help" is not so hard way to discover it.
The question is whether it would be possible to not print terminal sequences
*by default*;  not how it can be done.  But yes -- as it obviously works on
F23, there is no need to change anything.

>  I suspect perldoc sets LESS=-R. I dont' have the variable in my
> environment: 
That's right.

>  From my point of view, perldoc is fine in Fedora. This is issue in
> RHEL-7's
>  perldoc. 
Correct.

(In reply to Petr Pisar from comment #2)
>  Actually I cannot reproduce it in RHEL-7 either. Thought it works
> there
>  probably for some other reason. If you want to open a bug for RHEL-7, I need
>  the reproducer. 
In RHEL7, I'm able to reproduce it.  Perldoc does not set the LESS variable,
can be debugged by:

  $ cat lesswrap
  #! /bin/sh
  env | grep -i less
  less "$@"

  $ PAGER=./lesswrap perldoc perlreref

Petr, can you confirm?

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[Bug 1329059] Don't produce terminal control sequences in perldoc

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1329059



--- Comment #4 from Pavel Raiskup <praiskup(a)redhat.com&gt; ---
(In reply to Pavel Raiskup from comment #3)
>  In RHEL7, I'm able to reproduce it.  Perldoc does not set the
> LESS variable,
>  can be debugged by:
>  
>    $ cat lesswrap
>    #! /bin/sh
>    env | grep -i less
>    less "$@"
>  
>    $ PAGER=./lesswrap perldoc perlreref
>  
>  Petr, can you confirm? 
While, of course, you can use:

  $ PERLDOCDEBUG=1 PAGER=./lesswrap perldoc perlreref
  $ # hit the CTRL^Z
  $ # open the temp file generated by perldoc to see that the color sequences
    # are there.

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[Bug 1329059] Don't produce terminal control sequences in perldoc

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https://bugzilla.redhat.com/show_bug.cgi?id=1329059



--- Comment #5 from Petr Pisar <ppisar(a)redhat.com&gt; ---
Yes, in RHEL-7 if the PAGER is defined, then the ANSI sequences are not
interpreted.

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[Bug 1329059] Don't produce terminal control sequences in perldoc

https://bugzilla.redhat.com/show_bug.cgi?id=1329059

Petr Pisar <ppisar(a)redhat.com&gt; changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://bugzilla.redhat.com
                   |                            |/show_bug.cgi?id=1614708



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