Add Debian terminfo directory default to find_terminfo_file

[christiangnrd]

Without this, Base.current_terminfo returns TermInfo(String[]; 0 flags, 0 numbers, 0 strings) because it cannot find the correct terminfo files. In the regular terminal, there was basic color and formatting functionality because $TERMs starting with xterm are treated specially, but in a tmux session, where the $TERM = tmux-256color, there was no color at all.

This also has the side-effect of enabling strikethrough and italics in the default gnome terminal emulator.

The readme found in /etc/terminfo/README (as mentioned in terminfo(5) "Fetching Compiled Descriptions") says the following:

/etc/terminfo/README 
This directory is for system-local terminfo descriptions. By default,
ncurses will search ${HOME}/.terminfo first, then /etc/terminfo (this
directory), then /lib/terminfo, and last not least /usr/share/terminfo.

I believe the manual might be different depending on the distro.

[christiangnrd]

I don't seem to have the permissions to officially request a review so I'm tagging @tecosaur in this comment.

[vtjnash]

I think we should add the full list from that README too

[tecosaur]

In principle, I don't see anything wrong with this, but I'm curious where /lib/terminfo and /etc/terminfo/README are coming from?

On my system, if I run man 'terminfo(5)' I don't see any reference to that README file (which doesn't exist for me), and I can't see it on https://www.man7.org/linux/man-pages/man5/terminfo.5.html either 😕.

[christiangnrd]

I think we should add the full list from that README too

I originally didn't add /etc/terminfo to the list because it was empty (except for the README) but I think you're right. Change made.

The rest is already handled by the function.

[tecosaur]

/etc/terminfo is also considered in #51198. Actually, I'm wondering if we could maybe merge that first/instead? If we're going to get more PRs to terminfo.jl it would be better if they build off that refactored version.

[christiangnrd]

@tecosaur What distro are you on? On Debian (raspberrypiOS) and Ubuntu 23.04, the manual has the following:

   Fetching Compiled Descriptions
       The  ncurses  library  searches  for  terminal  descriptions in several places.  It uses only the first description
       found.  The library has a compiled-in list of places to search which can be overridden  by  environment  variables.
       Before starting to search, ncurses eliminates duplicates in its search list.

       •   If  the  environment  variable TERMINFO is set, it is interpreted as the pathname of a directory containing the
           compiled description you are working on.  Only that directory is searched.

       •   If TERMINFO is not set, ncurses will instead look in the directory $HOME/.terminfo for a compiled description.

       •   Next, if the environment variable TERMINFO_DIRS is set, ncurses will interpret the contents of that variable as
           a list of colon-separated directories (or database files) to be searched.

           An empty directory name (i.e., if the variable begins or ends with a colon, or contains adjacent colons) is in‐
           terpreted as the system location /etc/terminfo.

       •   Finally, ncurses searches these compiled-in locations:

           •   a list of directories (no default value), and

           •   the system terminfo directory, /etc/terminfo (the compiled-in default).

[tecosaur]

I'm on opensuse, but I can't see the README mentioned on my NixOS server either, or:

• https://www.man7.org/linux/man-pages/man5/terminfo.5.html
• https://linux.die.net/man/5/terminfo
• https://man.netbsd.org/terminfo.5

which has me thinking this could be a "debian special"?

[christiangnrd]

Probably is. The readme is also missing from CentOS 8.

[christiangnrd]

@tecosaur I'll rebase once #51198 is merged.

[laborg]

In principle, I don't see anything wrong with this, but I'm curious where /lib/terminfo and /etc/terminfo/README are coming from?

The files in /lib/terminfo are provided by the debian package ncurses-base which, at least on ubuntu, is an "essential system-critical" (according to apt) package.

[imciner2]

which has me thinking this could be a "debian special"?

It isn't. The lack of these specified in the man page is because the terminfo directories can be specified as build time options.

For instance, the build configs of several distros are:

Debian:

--with-terminfo-dirs="/etc/terminfo:/lib/terminfo:/usr/share/terminfo" \

Fedora:

--with-terminfo-dirs=%{_sysconfdir}/terminfo:%{_datadir}/terminfo \

OpenSUSE:

--with-terminfo-dirs=%{_sysconfdir}/terminfo:%{_datadir}/terminfo \

Nix:

"--with-terminfo-dirs=${lib.concatStringsSep ":" [
  "/etc/terminfo" # Debian, Fedora, Gentoo
  "/lib/terminfo" # Debian
  "/usr/share/terminfo" # upstream default, probably all FHS-based distros
  "/run/current-system/sw/share/terminfo" # NixOS
]

[christiangnrd]

Rebased now that #51198 is merged. I tested it and it's able to find the tmux terminfo file on debian so ready to merge after review and/or passing tests.

[christiangnrd]

Test failure is unrelated