lib/portage/output.py provides xtermTitle() and xtermTitleReset() to set window titles for various xterm-like terminal emulators by wrapping the string with escape codes, namely '\x1b]0;%s\x07', which does not work as expected for terminal multiplexers like screen or tmux, setting their pane titles instead window titles especially in tmux. The correct escape codes to change window title in screen/tmux are '\033k%s\033\\' in octet or '\x1bk%s\x1b\\' in hex according to their manuals. But the current emerge outputs '\x1b]0;%s\x07' in those multiplexers anyway, not changing the window title but overriding the pane title, especially in tmux with default config showing truncated emerge status info on the right of its status line. Although tmux can be configured to show its active pane title on the window title, this is not a solution and gives inconsistent user experience as almost no command line program tries to change its multiplexer's pane title which are left for user's setting but now blindly overridden and gone by every emerge run. Since the terminal emulator/multiplexer handles the actual terminal's window title, the program running under it should follow the escape codes specific to the emulator/multiplexer in order to change the terminal's window title, otherwise it's crippled support. The patch fixes this by conditioning the escape codes to 'TERM' environ matching regex ^(screen|tmux). Other multiplexers besides tmux are not tested though. p.s. For multiplexers, letting emerge set the pane title also could be an option, but looks overbearing and xtermTitle()/xtermTitleReset() should be modified to somehow save and restore previous pane title in those multiplexers. Reproducible: Always Steps to Reproduce: 1. Without FEATURES="notitles", emerge any package within one of those terminal multiplexers, screen or tmux inside xterm or the likes. 2. Watch whether the emerge status info shows up at the window title of the terminal emulator. Actual Results: In tmux configured default except allow-rename, emerge's status info does not show up on the terminal window title but unexpectedly on the right side of its status line truncated very short. Expected Results: Within a terminal multiplexer or not, emerge's status info shows up on xterm-like terminal's window title. Vim also uses wrong escape codes for screen/tmux, but it can be corrected by changing its 't_ts' and 't_fs' variables. But emerge is hard-coded with the escape codes, thus needs to be patched.
Created attachment 568556 [details, diff] correct escaped codes to change window title in screen/tmux
Need one more setting for tmux: set-titles. To reproduce the issue with tmux in xterm-like terminals: 1. # emerge tmux 2. $ echo "set -g set-titles on" > ~/.tmux.conf 3. $ echo "setw -g allow-rename on" >> ~/.tmux.conf 4. Fire up xterm or the like and open tmux session in that terminal: $ tmux 5. Within the tmux session, check out the terminal window title and the right side of tmux status line. Emerge any package and observe the window title and the tmux status line change. Compared to direct emerging in xterm, the emerge status info does not shows up on the xterm window title with the tmux session but the truncated and quoted string of it appears on the right side of tmux status line. After the emerge, the title set by the shell prior to emerging takes the right side spot as emerge restores it with wrong escape codes.
After some testings, I find this can be considered not a portage bug. In tmux, letting pane titles be modified by applications running under it with XTerm's window title escape codes(\033]0; and \007) and setting up tmux to show its active pane title on the window title (plus, pane title on pane border status) seems more intriguing. But this needs somewhat unified setups between applications 'cause now they have two different ways to influence the window title, disparities in those configurations can lead to weird outcomes. For example, if the shell is using tmux's escape codes, VIM is using XTerm's and tmux is configured with set-titles-string to show both window title(#W) and pane title(#T) on the actual window title, recursively repeated title strings as many as times VIM invocated will happen. As VIM is saving/restoring actual window title to pane title and the shell is changing only window title(#W) leaving pane title untouched, a new VIM starts up again saving previous actual window title which is still dirty with previous VIM's pane title and so on. VIM expects saving and restoring previous window title--current VIM saves the actual window title and restores it with escape codes set in t_ts and t_fs--would be enough, but in tmux it's not. tmux intercepts those two sets of escape codes and handles application requested window title strings by the code set, using XTerm's codes to change pane title(#T) and tmux's codes to do window title(#W), leaving what the actual window title string should be up to user's preference. Also, tmux won't allow any application to directly change the actual window title. To fix the problem, configuring VIM to save previous pane title in tmux would be too special. However, one of the simple workarounds is with the shell's PROMPT_COMMAND or PS1 to purge dirty pane title VIM left. Another way to fix is to set VIM's t_ts and t_fs variable in accordance with the shell's preference or vice versa. So it is a problem of configuration mix-up. Setting up the applications window title escape codes to be only one set of them fixes the problem, i.e. use only the window title escape codes(\033k and \033\\) to update window title even by inactive pane's application or use only the pane title escape codes(\033]2; and \033\\ from tmux manual or \033]0; and \007 from XTerm) to get more distinguishable panes. Portage needs patching to use tmux's window title escape codes instead of XTerm's. Bash's default bashrc sets PS1 to use tmux's when TERM=screen* but user can set up PS1 either way. VIM uses the pane title escape codes regardless of TERM value but can configured by setting t_ts t_fs variables to use either one. To set PS1 in bashrc to use XTerm's escape codes and leave others to default would be less of work and more of distinguishable UX in tmux.
