Use the mouse to properly select text in less

lessterminal

I've just discovered that I can add the following lines to ~/.vimrc.

set mouse=a
:vmap <C-C> "+y

This has the effect of being able to select text with the mouse (i.e. in visual mode), and then copy the actual text to the X clipboard with Ctrl+c. This differs from the default copy from the terminal, as it's the real text I'm copying, not what the terminal sees. For example, if there were tabs in the text, then previously I'd copy them as spaces.

Is there a way to make less behave the same way? i.e. can I copy verbatim what is in the text file I'm viewing in less?

Best Answer

Not a task for less

No,
I do not think you can do that directly, because less does not have a cursor to begin with.
It would need one to navigate to start and end of the text to select.
less is just not the right tool for character-level navigation.

Tabs already expanded

You can use the key shift and the mouse to make a selection; This is handled by the terminal, not by less. But the terminal does not know how spaces and tabs where arranged - less does the interpretation of tabs internally, and writes only normal " " characters to the screen.

There are tools like screen, tmux and byobu, which can do lots of impressive things in this area. I did not check, but I assume that these terminal multiplexers do not have a way around that - being terminals, in the end - and will behave the same.

Use vim

If you are showing a file in less, there is a nice solution:
Press the key v in less to open the current file in vim - asuming your $EDITOR etc. is set up for vim.

This does not work when showing stdin from a pipeline or so, although there are workarounds.

Mouse scrolling, at least

But you can at least scroll with the mouse wheel:

That seems even to be enabled by default, but the mouse wheel events get suppressed by a different option.

For a quick test, try:

LESS=-r man less

The option -X (--no-init) blocks scrolling - check what your environment variable LESS contains:

$ echo $LESS

The option -q (--quiet, --silent) also causes trouble, according to SU: How to make mouse wheel scroll the less pager using bash and gnome-terminal?

Related Solutions

URxvt Terminal – Is It Possible to Select Tabs as Tabs with Mouse?

I don't know of any terminal that does, and I'll just say why I don't think any terminal does:

tab is one of the many characters that once displayed outputs more than one character on screen or moves the cursor. CR (move to beginning of line), LF (down), backspace (left) and all the escape sequences that move the cursor or change character attributes and/or don't display anything...

urxvt doesn't even get exactly what the application outputs. When an application sends a LF (\n) to the slave side of the pseudo-terminal, you'll notice that, most of the time, it does not just move the cursor down, as LF normally does, it also moves it back to the start of the line. That's because the pty driver translates the "\n" to "\r\n" before making it available for reading from the master side of the terminal by urxvt (you may use stty to change that behavior).

Also note that the selection will not capture trailing spaces.

The X selection selects the characters that are displayed, not the ones that have been sent by the application(s) to generate that display (consider that any character at any given position on the screen may have been overridden several times by one or more application(s)).

Some terminals though allow to capture all the characters that they receive on the master side of the pseudo-terminal, and if they don't, you can use "script" or "screen" to do it instead. But to get the output of an application into the X selection, you can also simply do:

the-command | xsel

Copy / paste text selections between tmux and the clipboard

Use the following tmux.conf with copy-pipe in the new versions of tmux (1.8+):

set -g mouse on
# To copy:
bind-key -n -t emacs-copy M-w copy-pipe "xclip -i -sel p -f | xclip -i -sel c "

# To paste:
bind-key -n C-y run "xclip -o | tmux load-buffer - ; tmux paste-buffer"

prefix+[ into copy-mode
select content with mouse(hold)
M-w to copy that part into system clipboard
C-y the paste it inside tmux, C-v to paste it inside other regular application like web browser.