Subject: bug#37564: [PATCH] don't export LINES and COLUMNS env vars in term to fix ncurses applications

From: Glenn Morris <[email-masked]>
Date: Mon, 20 Jan 2020 19:58:53 -0500

The report seems clear to me.

No other terminal emulator exports LINES and COLUMNS as environment variables.
Applications use ioctl to get the size.
   -> Therefore setting LINES and COLUMNS is pointless.
If LINES/COLUMNS are set, they override ioctl.
You can't update the environment of an already running process.
Therefore the presence of LINES/COLUMNS in the initial environment
of a process spawned from Emacs means it will fail to react to resizing.
 Therefore exporting LINES and COLUMNS is harmful.
(It's irrelevant if Emacs changes LINES and COLUMNS for new processes.)

So don't export LINES and COLUMNS.

I can't explain it any better.