For setting breakpoints, I was wondering if there is any way to copy the location of a line in a file opened in vim, to gdb rather than typing the whole file path and linenumber in the gdb shell?


2 Answers 2


Good, since you're using tmux then you can use send-keys (alias: send), a tmux command for inputting text into a different pane than the current one. You can call it from Vim using whatever data you need from there. For current (full) path and line number that would be expand('%:p') and line('.')

The following command will send those two strings (separated by :) to the terminal in pane 3. The combined string will not be submitted (i.e. carriage return is not sent).

:exe "!tmux send -t 3 '" . expand("%:p") . ":" . line(".") . "'"

So with, for example, a file /tmp/foo.txt and line number 33 the tmux command that will be executed from the shell is:

tmux send -t 3 '/tmp/foo.txt:33'

If you want to submit the sent string in the target pane (i.e. by sending a carriage return) you just need to replace the last "'" with "' Enter".

Regarding the -t param to send-keys:

  • In its simplest form, takes the target pane index as argument.
  • If you are sending your command to another pane in the same window that's the only form we need to know. (Otherwise read the man page and/or ask me.)
  • You can display pane indexes in the current window with tmux-prefix + q.

Obviously, if you're going to use this a lot you'll want to put it in a mapping and/or function. A mapping-only solution:

nnoremap XX :<C-U>exe "!tmux send -t " . v:count . " '" . expand("%:p") . " " . line(".") . "'"<CR>

Replace XX with whatever unused key or key combo you want. Determine the target pane index (used by -t) and, from Normal mode, type that number and then your XX replacement.

Though a little hard to read, the RHS of this isn't much more than the original exe command plus:

  • Insertion of the variable v:count where the -t value goes. v:count is a built-in variable that contains any number entered right before entering command-line mode (here that means the number entered before the the mapped key(s) are pressed).
  • <C-U> triggers Ctrl-U in order to clear the command line before we populate it. (Because when a number is entered right before entering command-line mode (:) the command-line is prepopulated with a line range and we don't want that here.)

Alternatively, you could prompt the user for a pane index with a function+mapping. Something like:

func! BufferInfoToPane()
    let l:pidx = ...prompt code here...
    exe "!tmux send -t ".l:pidx." '".expand("%:p")." ".line(".")."'"<CR>

With the mapping:

nnoremap XX :call BufferInfoToPane()<CR>
  • How to create a mapping for this? Also I have one more question, while making a mapping how can I make sure that I am not overwriting any existing mapping?
    – In78
    Commented May 6, 2019 at 0:05
  • 1
    Added a mapping. As for overwriting mappings you need to check manually whether something is mapped. :nmap <leader>X for normal mode mapping using "\X", for example (assuming default <leader> key).
    – B Layer
    Commented May 6, 2019 at 0:13
  • 1
    @ln78 Does it work for you?
    – B Layer
    Commented May 7, 2019 at 19:59
  • 1
    I'll take that as a yes. :)
    – B Layer
    Commented May 8, 2019 at 2:59

I have found one way which is to use the : terminal feature of vim to start a new shell, run gdb in it and paste the filename from the alternate register #.

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