Alt-[hjkl] doesn't work when $TERM is not xterm

[lacygoill]

According to $ man htop, M-j and M-k can be pressed to scroll in the list of processes. On my machine, it works only when $TERM has the value xterm or xterm-256color.

In tmux, $TERM must have the value screen, screen-256color, tmux or tmux-256color. Because of this, M-j and M-k don't work in htop inside tmux.

I can reproduce on the latest commit of the htop github repository.

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I don't think this is is a bug in tmux, because:

• I'm using a recent version (2 days old)
• I haven't found any relevant report on the issue tracker
• I can reproduce inside tmux with no config ($ tmux -Lx -f/dev/null)
• I can reproduce outside tmux with $ TERM=tmux-256color htop

I don't think the issue is in my tmux-256color terminal description, because:

• I have compiled the most recent version of terminfo:

   $ curl -LO http://invisible-island.net/datafiles/current/terminfo.src.gz
   $ gunzip terminfo.src.gz
   $ tic -sx terminfo.src

• I can reproduce with other TERM values, such as st-256color, gnome-256color, konsole-256color.

• As a temporary experience, I have compiled a custom terminal description for tmux-256color which is identical to the one of xterm, and the issue still persists.

I don't think the issue is in my shell, because:

• I can reproduce in bash, zsh and dash
• I can reproduce without any shell config ($ env -i bash --norc --noprofile, $ env -i zsh -f, $ env -i dash)

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As a workaround, I use this shell alias:

alias top='TERM=xterm-256color htop'

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Here's a gif to illustrate the issue:

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Environment:

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 16.04.6 LTS
Release:        16.04
Codename:       xenial

$ zsh --version
zsh 5.7.1 (x86_64-pc-linux-gnu)

$ xterm -version
XTerm(322)

[lacygoill]

I'm not sure this is a bug, because maybe the keys are not meant to be used there, but I've also noticed that M-[hjkl] don't work in some menus. For example, in the menu opened when you press l to get the list of files opened by the process under the cursor.

OTOH, C-[np] seem to work in all menus, and with any TERM value. I don't think they are documented – at least I couldn't find them here – but they are very handy, so I use them instead of M-[jk].