[BUGZILLA #16604] R does not recognize when terminal size changes

[MichaelChirico]

I am running R 3.2.2 under Arch Linux.

When I use R on the command line and resize the terminal, R does not take note of the changed terminal size. This is apparent when running a command whose output is long enough to wrap onto multiple lines (e.g. "letters"). It is, however, most inconvenient when entering a long command line. When I make the terminal smaller, for instance to share screen space with a plot window, then editing such a multi-line command becomes impossible, because Readline is confused about where the cursor is. Ctrl-A no longer visually takes the cursor to the start of the command, and when I enter some text after pressing Ctrl-A, the terminal becomes a mess of diagonal words. Since my plot commands are often very long (e.g. "plot(...); lines(...); abline(...); ...") and wrap onto multiple lines, and since plotting is what causes me to want to shrink my R terminal window temporarily, this bug is particularly inconvenient during the many occasions when I am trying to fiddle with a plot. I guess since it hasn't been fixed, other people must not be experiencing it with their setup or their way of using R - maybe they have bigger screens - but I noticed some related discussion on Stackoverflow:

http://stackoverflow.com/questions/1172485/how-to-increase-the-number-of-columns-using-r-in-linux

I also saw this bug:

https://bugs.r-project.org/bugzilla/show_bug.cgi?id=16259

I, too, find that the COLUMNS environment variable is not updated when the window changes. But this is rather beside the point, because what I want is for R to e.g. trap SIGWINCH and update the width and alert Readline to the change as well. For what it's worth, other command-line programs like Octave and the Unix shells all have the desired behavior.

Thanks for reading...!

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METADATA

• Bug author - Frederick Eaton
• Creation time - 2015-11-18 19:30:29 UTC
• Bugzilla link
• Status - ASSIGNED
• Alias - None
• Component - System-specific
• Version - R 3.2.2
• Hardware - Other Linux
• Importance - P5 enhancement
• Assignee - R-core
• URL -
• Modification time - 2016-11-12 15:54 UTC

[MichaelChirico]

I was looking into working on this bug and came across

https://bugs.python.org/issue23735

The above link documents (and fixes) the same problem in Python.
Apparently there was a change in signal handling behavior in Readline
6.3 due to a recognized need to conform with POSIX standards by not
calling certain functions from within signal handlers. The situation
seems to be well described at the above URL. Also, I believe that the
Python patch could be adapted fairly easily to apply to R.

One implication of the Python discussion is that R may have had the
correct SIGWINCH behavior prior to Readline 6.3. The same would apply
to proper SIGINT handling and Bug 16603. I did not start using R until
fairly recently, so I wouldn't know.

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METADATA

• Comment author - Frederick Eaton
• Timestamp - 2016-04-25 17:43:44 UTC

[MichaelChirico]

(In reply to Frederick Eaton from comment #1)

One implication of the Python discussion is that R may have had the
correct SIGWINCH behavior prior to Readline 6.3. The same would apply

I no longer have a system with a pre-6.3 readline and R, but from memory, this did used to work correctly in the past.

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METADATA

• Comment author - Terran
• Timestamp - 2016-04-28 15:51:44 UTC

[MichaelChirico]

Created attachment 2071 [details]
fix for Readline 6.3 ignoring-SIGWINCH bug

Let me know what needs to be changed before this can be accepted. Thanks.

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METADATA

• Comment author - Frederick Eaton
• Timestamp - 2016-05-02 22:10:05 UTC

INCLUDED PATCH

• ID - 1
• Author - Frederick Eaton
• Link to download patch - https://bugs.r-project.org/bugzilla/attachment.cgi?id=2071
• Timestamp - 2016-05-02 22:10 UTC
• Extra info - (1.54 KB, patch)

[MichaelChirico]

Frederick, thank you for the patch. I rebuilt R with it and I can confirm that it fixed the very annoying terminal width issue for me. If I can be of any assistance somehow in getting it accepted into R please let me know.

(In reply to Frederick Eaton from comment #3)

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METADATA

• Comment author - Terran
• Timestamp - 2016-11-11 23:03:00 UTC

[MichaelChirico]

(In reply to Terran from comment #4)

Frederick, thank you for the patch.  I rebuilt R with it and I can confirm
that it fixed the very annoying terminal width issue for me.  If I can be of
any assistance somehow in getting it accepted into R please let me know.

(In reply to Frederick Eaton from comment #3)

For some reason we forgot to say here, but this bug was fixed ... indeed (partly) thanks to Frederick's patch for R version R 3.3.2 (and newer) quite a while ago.

So, Terran, did you observe the bug in R 3.3.2 ???

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METADATA

• Comment author - Martin Maechler
• Timestamp - 2016-11-12 15:50:33 UTC

[MichaelChirico]

Ah; I just built 3.3.1 (the latest version available as source package for Debian stable), so the patch here applied cleanly for me and fixed the problem. I'll try to verify on a newer version that it's fixed as released and let you know here.

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METADATA

• Comment author - Terran
• Timestamp - 2016-11-12 15:54:59 UTC

[github-actions]

I think that the loss to follow-up here indicates that this bug was indeed fixed for R 3.3.2. Corresponding NEWS item:

Versions of the readline library >= 6.3 had been changed so that terminal
window resizes were not signalled to readline: code has been added using a
explicit signal handler to work around that (when R is compiled against
readline >= 6.3). (PR#16604)

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METADATA

• Comment author - Sebastian Meyer
• Timestamp - 2020-07-09 17:56:03 UTC