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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.


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)
  • wall clock execution time of command if it's longer than one minute
  • 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)
  • 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?)
    • Note: this is almost entirely untested
  • live updating load average (colourised with thresholds. invisible below 0.4)
  • live updating of time (or, if on battery, then battery discharge/charge info (I show minutes remaining for either when < 1hour, otherwise % of battery. Colour indicated charging (green/greenbold) vs discharging (yellow/yellowbold/redbold/redboldinverted). Battery required 'acpi' command with expected output to parse.
  • live updating of 'biff'. ie, number of mailboxes with unread mail (Maildir++ format mailboxes only. Notes in Mutt indicate the basis of this)
  • current tty

Extra Notes

  • The initial greeting recurs if the '$msg' variable is non-empty. It is echoed to the screen, then the prompt cleared to a new line with a refresh after only 1second.
  • All "live" updates are at a 20 second refresh rate. Live updating also ensures that an abandoned prompt will keep-alive a remote shell over dodgy NAT :)
  • The first prompt after any command always shows time with seconds, and does NOT show TTY or battery. They appear only after the first refresh

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 ?

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 :)


My current prompt config is findable here:

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.

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