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Tag: PRIMARY

XSel, for command-line operations on X selections

January 31, 2010 /

Since I first learned that Windowmaker installs two command-line tools, wxcopy and wxpaste, to play around with X selections, I have wanted to be able to make and use X selections from my Bash shell. wxcopy and wxpaste never did what I expected them to do, so I gave up until recently I learned about all the different X selections.

By default, wxcopy and wxpaste operate on the CUT_BUFFER[n] selections. These are deprecated. That’s why I could never make it work, because modern applications use only CLIPBOARD and SELECTION. So, wxcopy is pretty useless (unless its used to copy something to paste with wxpaste). With this knowledge wxcopy does seem useful thanks to its -selection [selection-name] flag, but this doesn’t seem to work; I only get the contents of CUT_BUFFER. This is not how the feature is advertised:

-selection [selection-name]
The data will be copied from the named selection. If cutting from the selection fails, the cutbuffer will be used. The default value for the selection name is PRIMARY.

Enter XSel

Fortunately, there’s XSel by Conrad Parker, a program which made him passionately hate the ICCCM.

XSel does exactly what it advertises. I’m actually surprised that I never heard of it before. It’s available in Gentoo, Debian and Ubuntu, so it’s a breeze to install.

Among its features are: --append, --follow, --clear, --delete (very weird, but logical if you understand X IPC), --primary, --secondary, --clipboard, --keep, and --exchange. Read the man page for more. It’s an excellent read.

One of the places where I’m going to use this tool is when copy-pasting to and from VIM. I really like how this compares to using :insert or :r!cat</dev/tty and then using the pointer to paste (or (Shift+)Insert with my custom XTerm config). Now, to paste something in VIM, I can simply type:

:r!xsel

I use the following to copy any amount of text from VIM. This works much better than fooling around with the mouse:

:'>,'> !tee >(xsel -i)

The '>,'> range is entered automatically if you press : while in visual (selection) mode. You could enter any range there, or even % to select the whole file. To copy to the CLIPBOARD instead of the PRIMARY, use xsel -i -b in the above example.

If someone know of a way to make VIM pipe something to a program without replacing the given range with that program’s output, I could simplify this…

Copy-pasting to and from XTerms

January 31, 2010 /

By default, XTerms only supports the PRIMARY selection for copy and paste. The PRIMARY selection is the one that is used by most ‘modern’ X application when you select text. This text can then usually be pasted by clicking the middle/second mouse button. Because this selection is set whenever you select, it’s easily overwritten, often accidentally. That’s why most newer X apps offer a parallel copy/paste mechanism where the selection is only explicitly set by choosing “Cut” or “Copy” from the application’s “Edit” menu or from its context menu (or with the Control-X/C/V keyboard shortcuts). In X, this selection is called CLIPBOARD, just like in Windows where it’s the only selection.

X also has these selections called Cut Buffers, but these are considered obsolete. Maybe that’s just too bad, because they appear to be the only selections with persistence; the other selections, PRIMARY and CLIPBOARD, disappear when the application is quit. Apparently, this is a feature, because it enables content negotiation.

Anyway, XTerm can be configured to do anything and I want it to be CLIPBOARD aware, for two reasons: one is that I often copy things from applications that can only set the CLIPBOARD selection; another is that I want to be able to really copy something from the XTerm, without losing it as soon as I select something else (especially if that something else is something I want to replace with the selection).

So, I added the following to my VT100.Translations #override in .Xdefaults.XTerm:

XTerm*VT100.Translations: #override \
    ShiftInsert: insert-selection(CLIPBOARD) \n\
    Insert: insert-selection(PRIMARY) \n\
    Shift: insert-selection(CLIPBOARD) \n\
    Shift: select-start() \n\
    Shift: select-extend() \n\
    Shift: select-end(CLIPBOARD)

What this does:

  • This gives me an XTerm that pastes the content of the CLIPBOARD when I hold down Shift during my two-finger tab (I’m using a touchpad, so that works as a Btn2).
  • Because I don’t like moving my hands, I can do the same by pressing Shift+Insert.
  • I can use my Insert key without Shift to paste the PRIMARY selection.
  • To copy something to the clipboard, I hold down the Shift key while making the selection.

That’s how you can make use of the CLIPBOARD from your XTerm.

Sources

If you want to learn more.

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