SecondarySelection

Emacs has a primary selection, called the region. It also has a secondary selection. What for?

Use the secondary selection for, well, a second selection. This lets you use the region for other things, while keeping another selection available for yanking etc. In other words, think of the secondary selection as something less ephemeral than the region, something that is unaffected by changes in the region, i.e., a selection that stays put even as you move the cursor to a different position (point).

Using the Secondary Selection (Vanilla Emacs)

How do you use the secondary selection? See Secondary Selection. Selection and yanking are the same as for the region, except that you use the Meta modifier key.

• To select, do any of the usual things, but with the Meta key held down:
  • Hold the Meta key while you drag the mouse (mouse-1).
  • Meta click mouse-1, then Meta click mouse-3, to select a sequence of characters.
  • Meta double-click mouse-1, then Meta click mouse-3, to select a sequence of whole words.
  • Meta triple-click mouse-1, then Meta click mouse-3, to select a sequence of whole lines.
• To yank (paste): Meta click mouse-2.

You can also use the secondary selection as another way to do what you do with ‘query-replace’ – sometimes it is more convenient or more flexible:

1. Select the replacement text as the secondary selection.
2. Select the text to replace as the primary selection.
3. Paste the secondary selection.
4. Kill the primary selection.

Library `second-sel.el' - Secondary Selection Enhancements

Library second-sel.el enhances secondary selection.

It adds the secondary selection to a new selection ring, ‘secondary-selection-ring’, which is similar to, but separate from, the ‘kill-ring’. It also prevents the secondary selection from being added to the ‘kill-ring’, so you now have two separate selection-history rings.

‘M-y’ cycles items from the appropriate ring, depending on whether it follows a yank of the primary (region) or the secondary selection (see below).

second-sel.el defines new secondary-selection commands. Library menu-bar+.el adds some of these to the Edit menu as items Paste Secondary, Move Secondary to Region, Swap Region and Secondary, and Select Secondary as Region.

[:secondary-yank|select|move|swap]

`secondary-yank|select|move|swap' (`C-M-y')

Command `secondary-yank|select|move|swap’ rolls several secondary-selection commands into one. Library setup-keys.el binds this to ‘C-M-y’.

Its behavior depends on the prefix argument:

• No prefix arg – same as ‘yank-secondary’ (also defined in second-sel.el): Yank the secondary selection at point.
• Zero prefix arg – same as ‘secondary-to-primary’: Select the secondary selection as the region, popping to its buffer.
• Non-zero arg: Move the secondary selection to this buffer’s region.
  • Negative arg – same as ‘secondary-swap-region’: Swap the region and the secondary selection. That is, also go to where the secondary selection was and select it as the region.
  • Positive arg: Same as ‘primary-to-secondary’.

DWIM summary: Use ‘C-M-y’:

• Define the secondary using the keyboard (‘C-1 C-M-y’).
• Go to the secondary location and select it (‘C-0 C-M-y’).
  • And put the secondary where the region is now (‘C-- C-M-y’), so you can easily bounce back.

`isearch-yank-secondary' (`C-M-y' in Isearch)

In Isearch, ‘M-y’ yanks the current kill into the Isearch string. Library setup-keys.el binds command ‘isearch-yank-secondary’ to ‘C-M-y’ for Isearch, so you can yank the current secondary selection.

`yank-pop-commands' (`M-y')

Library setup-keys.el binds command ‘yank-pop-commands’ to ‘M-y’. It cycles among selections in a selection ring: either the ‘kill-ring’ or the secondary-selection ring.

• If the previous command was a normal yank, then cycle the ‘kill-ring’.
• If the previous command yanked the secondary selection, then cycle the secondary-selection ring.

`M-y' at Top Level

If the previous command was not a yank at all (from either the ‘kill-ring’ or the ‘secondary-selection-ring’), then ‘M-y’ does nothing in vanilla Emacs. Here are two alternative enhancements that work together with second-sel.el to let you yank arbitrary entries from either selection ring.

• If you use library browse-kill-ring+.el then a top-level ‘M-y’ means browse the last-used selection ring. With a prefix argument, or if you are already in a selection-ring browse buffer, it browses the other selection ring.
• If you use Icicles then a top-level ‘M-y’ means yank by completing against either the ‘kill-ring’ or (with a prefix argument) the ‘secondary-selection-ring’. IOW ‘M-y’ yanks a kill using completion, and ‘C-u M-y’ yanks a secondary selection using completion.

Defining and Deleting the Secondary Selection using the Keyboard

The second-sel.el sections above show that you can use the keyboard instead of the mouse to yank the secondary selection. You can also use keyboard keys to define it, extend/retract it, and delete its text. Anything you can do with it using the mouse you can also do using keyboard keys.

• Command ‘set-secondary-start’ (I bind it to ‘C-x C-M-SPC’) sets the start of the secondary selection at point. This also undefines it, e.g., if it was defined in some other buffer.
• Command ‘secondary-save-then-kill’ (I bind it to ‘C-x C-M-RET’) does the same thing that ‘mouse-secondary-save-then-kill’ does (e.g., bound to ‘C-M-mouse-3’ or ‘M-mouse-3’), but it uses point instead of the ‘mouse-3’ click position. That is, it sets, extends/retracts, or deletes the secondary selection.

Using a Touchpad with the Secondary Selection

If you’re using a touchpad (this is on CentOS 7.2), some actions are easy to remember:

• One way to select the region:
  • Meta tap on the location of one end of the region.
  • Meta two-finger-tap on the other end of the region. Can be before or after the first.
  • Meta three-finger-tap at the location you want to paste. The previously marked region is still is still in place and still highlighted. Pasting in this way can be done multiple times.
• Other ways to select the region using a touchpad:
  • Meta double-tap-and-drag. That is, hold down the Meta key (generally “Alt”) and tap-tap-drag from one end of the region to the other.
  • Meta double-tap on a word to make that one word the region.
• Once you have a region selected, you can change the beginning and/or end of it:
  • If you initially select the region using Meta two-finger-tap, changing an endpoint of that region will be selected in whole word units only, i.e., an endpoint of the region won’t fall in the middle of a word. If, on the other hand, you initially designate the beginning of the region with Meta tap, a subsequent Meta double-tap (tap-tap) will designate where the pointer is at that time, even in the middle of a word.
  • Meta two-finger-tap at a location before the current region to expand the region to that location.
  • Meta two-finger-tap at a location after the current region to expand the region to that location below.
  • Either of the above two actions can be performed multiple times, each time changing the beginning or end points of the region, respectively.

If something happens which you don’t want, you can do C-/ to undo– multiple times, if desired.

See Also

• AnchoredTranspose makes use of the secondary selection.

CategoryEditing CategoryGlossary CategoryRegion