Revision as of 11:27, 26 June 2011

As a commandline junkie, my prompt is important. It is a key element to my interface.

It needs to be both informative and terse (I can't stand 2line prompts for eg)

I have used ZSH as my shell of preference since roughly the turn of the century. (previously: bash). Part of the incentive to switch was the prompt interface features found in zsh that were not in bash at the time. (my memory has right-aligned-prompt as notable, but I'm sure there were more reasons than just that ;)

The prompt I use dates it's heritage back to an old dos (specifically: 4DOS) prompt that I setup in... 1994, for a guess.

Features

currently implemented

prompt action

• Verbose date/time and $USER greeting on the very first prompt. This detail never recurs. I don't need $USER every prompt, since this custom prompt is enough to indicate to me that it's my account. I do not use this prompt on any other user accounts, nor as UID=0. (despite being configured to handle that usage gracefully)
• last job exit status (invisible when zero)
• host:path in network friendly (ish) format
• path shortening to last three components, plus subtle visual indication when this occurs (deliminating colon changes from host colour to directory colour, and '…' appears as the first element)
  • this shortening balances path context needs with space limitations. and is why the preceeding 'network friendly' format is "ish" :)
• path colourisation to indicate whether $PWD is RW or not (not usually means RO, but may also mean 'directory does not exist')
• count of background jobs (invisible if zero)
• ^ and $ reminder mnemonic for regex start/end line matching (I have a dyslexia about this!)
• priveliged user (usually UID=0) indication. Using # instead of $
• bang (!) hints (ie, history event number)
• VIM keybinding 'command' mode indication
• version control system repository information (supports bzr, git, svn, cvs... others?)
• live updating load average (colourised with thresholds. invisible below 0.4)
• live updating of time
  • "live" for both of these is at a = "20 second refresh"
  • this refresh ensures that an abandoned prompt will keep-alive a remote shell over dodgy NAT :)
  • first prompt after a command shows time with seconds in favour of the TTY, and following refresh forces a newline. The upshot of this is that you have both start (to the minute) and end (to the second) time of every command run. Think of it as the poor-mans `time $0` (with the caveat that the right-prompt does not show if the $PWD or $0 is too long)
• current tty

under consideration / TODO

these have been suggested, but not yet implemented. Or maybe I wont implement them - but I haven't decided yet

• make priv user prompt (#) be an alternate colour
• make the first prompt reset wipe the visibility of any half-written command in that location
• remove history event hint, or change format to eventnum@time ?

• moving the vcs_info to replace the host:path element, since within a vcs, it's often a different command namespace.
  • example of vcs_info
• per-host auto-colourisation
  • http://screwtape.jottit.com/per-host_prompt_colouring
  • http://ft.bewatermyfriend.org/comp/zsh/functions/prompt_ft_setup.html

• • note comment from screwtape: http://identi.ca/conversation/31704527#notice-31817077
• active group when not default

ignored / NOT be implemented

note: some of these I just don't use (or at least, ever expect to), others were clearly suggested in jest :)

• count of subshells
• http://www.facebook.com/#!/nemothorx?v=wall&story_fbid=121814377837169&ref=mf
  • Free disk, highest mem and CPU process, length of current prompt! -- Norgus
  • current Dow, weather and TV listings -- Julian

Configuration

My current prompt config is findable here:

http://wiki.thorx.net/~nemo/m/zfunk/

Using single quotes around $PS1 and $RPS1 to delay evaluation of variables until the prompt is displayed requires that you have the PROMPT_SUBST option set.

If the output of $RPS1 isn't remaining on the line with $PS1 after a command is executed, unset TRANSIENT_PROMPT option.