Irreal

I’ve been using undo-tree for a long time but mostly I just take advantage of it’s (very much improved) redo functionality. The other day, I saw this tweet

Or just use M-x undo-tree-visualize to go to anywhere in any of your pasts #emacshttps://t.co/FudQrDBkVB

— Johan Lindstrom (@jplindstrom) September 23, 2016

which inspired me to try to learn a bit more about undo-tree‘s features. The first thing, as suggested by the tweet is that you can step through the undo tree and your buffer will reflect the buffer state at that point in the undo tree. Once you get the buffer to the desired state, you can make that the current buffer or you can save that state to a register for later retrieval.

The main problem with undo-tree is that it’s feature rich and a bit hard to figure out how things work. Fortunately, there’s a long commentary at the head of the source file that serves as a tutorial. If you read through that once or twice you’ll have a good idea of what it can do.

What undo-tree really needs, I think, is a good video tutorial. Emacs Gifs has a short video on undo-tree-visualize but it doesn’t really show the power. I vaguely remember Magnar Sveen discussing it but I don’t think it was one of the Emacs Rocks videos. Mike Zamansky sometimes stops by Irreal; perhaps he’ll put it on his list of future Emacs videos. Sadly, I’m neither set up nor temperamentally suited to do the video so consider this a shameless attempt to get someone else to do the heavy lifting.

UPDATE [2016-10-06 Thu 19:42]: Fixed link to Emacs Gifs.

If you’re like me and try to stay in Emacs as much as you can, you have probably tried eshell. It’s a nice Emacsy shell (Mickey has an excellent eshell tutorial you should check out) but can sometimes have problems with applications that do direct cursor addressing.

It turns out that it’s easy to teach eshell to run such applications in a term buffer so that things still work. The most common examples of such apps are less and top (at least for my workflow). All you need to do is tell eshell to treat these applications specially and everything works just fine.

The TL;DR is that you should read Mickey’s tutorial and set eshell-visual-commands to run problem applications in a term buffer.

UPDATE [2016-10-04 Tue 14:33]: At least in Emacs 25, it turns out that eshell-visual-commands is already defined to a reasonable default list. You may want to add to it for other problem applications that you discover.

UPDATE [2016-10-05 Wed 12:07]: shell –> eshell

If you’re the type of writer who likes to move text around as you edit, you might find this Emacs package helpful.

Reminds me of the amazing things you cand do in #emacs org-mode https://t.co/5HI0MGwYg6

— John (beyond sleepy) (@jr0cket) October 1, 2016

I like how you can specify a region and then move the whole thing. Sure, you can highlight the region, kill it, and then yank it back at the new location but move-text lets you move it around at will and try different locations.

If you use Emacs strictly for coding, you may not find move-text useful but if you’re writing papers, reports, novels, or some other type of creative writing, it may be just what you need.

Wilfed Hughes offers an excellent tip

Emacs command of the day: eww-search-words, bound to M-s M-w. Do a web search for the text in the current region using the built-in browser.

— Wilfred Hughes (@_wilfredh) October 1, 2016

You can highlight a region in an Emacs buffer and invoke eww to search for the text in that region. I like it because I’m not forced out to a browser; everything stays in Emacs. The search engine is, of course, configurable. It will use whatever you have eww configured (via eww-search-prefix) to use.

An odd but very useful feature of Emacs is (file) local variables. This allows you to specify certain Emacs variables either on the first line of a file or at the end in a special Local Variables block. Typical uses include specifying line lengths, indention amounts, and other formatting features and specifying how to compile the file so that the compile command will work correctly.

I described it as odd because I first encountered the Local Variables block before I became an Emacs user and I thought it was very odd to see that sort of thing in a C source file. Regardless, local variables can be very useful.

One problem with them is what happens if you change a value or when you first add them to a file. How do you get Emacs to recognize the new value? I always solved this problem by reloading the file with Ctrl+x Ctrl+v (find-alternate-file) but there are other, better ways.

Grant Rettke over at Wisdom and Wonder points to two methods for reevaluating local variables. One method re-runs the hooks associated with the file and the other method doesn’t. Hop on over and take a look; it will take you less than a minute.

I try to use ehsell as much as I can when I need to drop into the shell. That way, I stay in Emacs and still have the power of Emacs available. The other day in a post about something else, I saw this powerful use of cd mentioned.

You can cd into a directory on another machine like this

cd /ssh:aineko:org

This logs me into my iMac in the ~/org directory using tramp. Something like

cd /ssh:aineko:

is the same as connecting to aineko with SSH. If you need to log into the remote server as a different user, use something like

cd /ssh:different_user@aineko:

It’s not quite completely transparent but it does make remote machines seem like they’re mounted locally. Very nice. And powerful.