Tales from the Gryphon

Or theming PS1

I am not fanatical about my command prompt. No sirree, not me. It is just that I spend half my life either staring at an Emacs window, or at an xterm command prompt; so even a marginal boost in productivity goes a long way. And I am often logged in over ssh to machines half a continent away, and am still comfortable enough on the Linux VT to spend time there, and I often do not have the GUI gew-gaws feeding me data. Hmm. Data. inpuuut. No. Must focus.

With all these open xterms and Emacs terminal mode frames floating around, it is easy to lose track of where I am on each terminal, and what the working directory is. So I want my command prompt to help me keep track of where I am. If the terminal is an xterm, the title can be setup like

 "user@host:../shotened/path/to/current/working/dir"

I want to know what machine, id (am I root?), and directory I am in. If I am deep down in the labyrinths of some work related directory tree, I want the path to be pruned, from the left, one component at a time. However, this does not help me on the console; so I also want the path to be in the command prompt; but it should not take up too much of the command line; and ideally, should just go away as I type a longish command. Gawd, I love zsh.

I once did a analysis of the command history. The most often used command sequences were

 cd some-place, ls

So. pwd and ls. I really really want to see the directory listing when I change directory to a new one. As one grows old, memorizing the directory contents for dozens of machines all the time taxes the gray cells a bit. So, I figure, why not let the command prompt handle all that? Having the current working dir always visible cuts down a heck of a lot on the pwd commands, and so all that’s left is to insist that the command prompt thingy always run ls after a change directory. Simple enough. Saves on typing. And time. And this is not just some crazy talk.

I want help with noticing whether the previous command exited with an error status (useful for commands that normally do not create an output).

If I am logged in to a machine on battery power, I want to know that. I also like visual cues to the amount of power remaining (good for my laptop on the long flights). I don’t want to have to know f the machine uses APM or ACPI, I just want my prompt color to change as the power fades.

I want my command prompt to let me know if I am in a directory which is under version control, and if so, what branch I am on. (I occasionally have to come in contact with arch, bzr, git, subversion, svk, and mercurial). If I am in a version controlled project, where I am relative to the root of the checked out tree is often more important than the absolute path, so I want to see relative paths, not absolute paths.

I want to know if there are uncommitted files in the working directory. Visually. I want to be reminded if I am in the middle of an ongoing

 rebase -i .

This is not asking for too much, is it?

So, here is a screen-shot of this in action: I start from my home directory, go to a directory not under version control, go to a project under git, then a different project with uncommitted files, and then finally to a subversion checkout. All with an angry fruit salad of colors warrantied to make Martin Krafft want to claw his eyes out . If you use zsh, then just grab hold of this, and then do:

 autoload -U promptinit
 promptinit
 prompt manoj

This might be a bit of a hit on slow machines, but even my laptop is a core 2 duo, so I do not find it noticeable.

Oh, and if you liked this article, you might also like Theming Emacs, and Theming XTerms.

Or configuring LS COLORS

After successfully Theming Emacs, I decoded to turn my efforts to providing more copacetic colors in other aspects of my working environment. I’ll write more about my effort to write my own color theme for fvwm when it is closer to being done. For now, I’ll concentrate on “ANSI Colors” in XTerms, and how one may theme those. The old Tektronics (or ANSI) terminals had 8 colors, namely, black, red, green, yellow, blue, magenta, cyan, and white. These colors had a normal, and a bright mode. The default set of colors is OK, but is not optimal, since they have to work on both dark and light backgrounds; however, I use mostly dark background colors.

Given that, I set to design my own colors, using fully laturated colors, with a base luminosity of 70, and equally spaced in chroma — and used the same saturation and chroma, but a luminosity of 80, for the bright set. This results in a pleasant pastely set of colors, which are e4asy on the eyes, when used on very dark backgrounds. The configuration can be seen in XTerm. I set the colors for rxvt as well as xterm. Now, the most noticeable effect of these changes is if using the color option for ls, therefore the next thing to do was to configure the colors used by ls using a utility dedicated for that task, namely, dircolors. By trial and error, I modified the default configuration provided by dircolors and ended up with dir colors, with the results as you see.

Using org mode to write ikiwiki posts

I have been much taken by org-mode in Emacs recently. Firstly, this has allowed me to actually effectively implement the tenets of “Getting things done”, which is amazing by itself. I always used to start with great enthusiasm, which rarely lasted longer than a week. Until org-mode. Then this is so amazingly flexible. It has better handling of tables and even a spreadsheet mode than anything I have used — and it has a pretty decent HTML export function. I practically live in org-mode on work days now. I strongly recommend org-mode, from things like agendas, TODO lists, calendars, appointments, articles, and now Ikiwiki posts.

I rarely ever use markdown, apart from blogging using Ikiwiki – and thus, since I blog so infrequently, I rarely ever remember all the syntax. On the other hand, org-mode syntax is now at my finger tips — so I decided it was time to write a Ikiwiki plugin so I can now write my blog posts using syntax I can actually remember. It is still rough around the edges – firstly, this requires emacs23 (or, on Debian, there is the unofficial emacs-snapshot package), secondly, it uses hueristic hacks to prune away the bits of the stand alone HTML page that org-mode creates; all I can say is that it currently works for me, as you can see from this post. How git this is for mainlne inclusion is another matter.

The code is here: org.pm. It can be dropped in to the Ikiwiki plug-in directory, and that’s all you need. With this, Ikiwiki pre-process things in the input file, and then passes it to emacs to htmlize it.