tmux copy mode search for a Unicode string

Question

In tmux's copy mode, I cannot search for a Unicode (non-ASCII) string, tmux just doesn't show (and just ignore) non-ASCII characters in the "Search Up:" prompt!

In ~/.tmux.conf, I have:

setw -g utf8 on
set -g status-utf8 on
set -g mouse-utf8 on
...

And I use

tmux -u

to start tmux (version 1.6) in xterm. (I've also tried this in urxvt and got same result.)

Any suggestions? Is searching with Unicode string supported? Thanks.

Answer 1

Unfortunately, it looks like only non-control ASCII is currently accepted.

See the MODEKEY_OTHER handling in window_copy_key_input() of window-copy.c.

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The underlying comparison code (window_copy_search_compare()) looks like it handles UTF-8 mode, so you might be able to get some basic functionality by simply allowing bytes greater than 127 to be added to the buffer. There are (at least!^†) some small problems if you do this though:

• Backspace still deletes one byte at a time. This can leave partial UTF-8 sequences in the buffer which seem to confuse the UTF-8 comparator (the resulting buffer matches everywhere!).
• Combining characters are not handled specially.
  As an example, the codepoint sequences U+00E9 and U+0065 U+0301 both look the same, but will compare as different (though each does compare as equal to itself).

You might want to ask on the tmux-users mailing list for better-founded advice.

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^† There could also be large problems (e.g. crashing and killing all your sessions); I do not know the code well enough to guess.