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.