Bash – How to stop screen from clobbering the titles

Let me see if I have deciphered your screen configuration correctly:

• You use something like logfile "%t-screen.log" (probably in a .screenrc file) to configure the name of the log file that will be started later.
• You use the title <hostname> (C-a A) screen command to set the title of a new window, or
  you do screen -t <hostname> ssh0 <hostname> to start a new screen session.
• You use the C-a H (C-a :log) screen command to toggle logging to the configured file.

If so, then is nearly equivalent (requires tmux 1.3+ to support #W in the pipe-pane shell command; pipe-pane is available in tmux 1.0+):

• In a configuration file (e.g. .tmux.conf):

  bind-key H pipe-pane -o "exec cat >>$HOME/'#W-tmux.log'"
  

• Use tmux rename-window <hostname> (C-b ,) to rename an existing window, or
  use tmux new-window -n <hostname> 'ssh <hostname>' to start a new tmux window, or
  use tmux new-session -n <hostname> 'ssh <hostname>' to start a new tmux session.
• Use C-b H to toggle the logging.

There is no notification that the log has been toggled, but you could add one if you wanted:

bind-key H pipe-pane -o "exec cat >>$HOME/'#W-tmux.log'" \; display-message 'Toggled logging to $HOME/#W-tmux.log'

Note: The above line is shown as if it were in a configuration file (either .tmux.conf or one you source). tmux needs to see both the backslash and the semicolon; if you want to configure this from the a shell (e.g. tmux bind-key …), then you will have to escape or quote both characters appropriately so that they are delivered to tmux intact. There does not seem to be a convenient way to show different messages for toggling on/off when using only a single binding (you might be able to rig something up with if-shell, but it would probably be ugly). If two bindings are acceptable, then try this:

bind-key H pipe-pane "exec cat >>$HOME/'#W-tmux.log'" \; display-message 'Started logging to $HOME/#W-tmux.log'
bind-key h pipe-pane \; display-message 'Ended logging to $HOME/#W-tmux.log'

Your shell configuration is setting the terminal title to the command that's currently running. It's a fairly common configuration. Since it's done by the shell, it isn't done if the shell is running on another machine with a different shell configuration. The escape sequence to set the Screen window title is ␛kTITLE␛\ where ␛ is the escape character (byte value 27).

In bash, look for code that emits this escape sequence. The escape character is probably represented as \e or \033. The code could be in the prompt (PS1) or in the command that's executed before displaying a new prompt after running a command (PROMPT_COMMAND). Check their values (taking care not to emit the escape sequences to the terminal in case they contain a literal escape character):

printf 'PS1=%s\nPROMPT_COMMAND=%s\n' "$PS1" "$PROMPT_COMMAND" | cat -v

It's also possible but less common to emit this escape sequence before running a command, via the DEBUG trap:

trap -p DEBUG

These variables (or the trap) would have to be set in the bash configuration, either yours or system-wide: normally ~/.bashrc, and /etc/bash.bashrc on some systems, but also possibly ~/.bash_profile, ~/.profile, /etc/profile or ~/.bash_login, or a file included by one of these. You can narrow it down by running a new shell with fewer settings:

env -i bash                  # no environment variables or per-user settings
env -i HOME="$HOME" bash     # no environment variables, normal interactive shell
env -i HOME="$HOME" bash -l  # no environment variables, login shell
HOME=/none bash              # skips your per-user settings

A comparison on which of those exhibits the problem will tell you whether the settings come from your settngs or system-wide ones, and whether they're from .bashrc (read by interactive shells) or from a login-time file (.profile, etc.).