lw -- get the last word using Vim motions

lw is a small Bash script I put together to (1) help practice my Vim motion skills, and (2) do something I want to do a lot: paste a fragment of a previous command's console output into a command line I'm typing.

It requires Vim (no particular version), tmux (no particular version) and bash.

Note: not intended to be actually more efficient than cut-n-paste. It will sharpen up your vim-fu though.

Usage

lw <vimkeys> <history-offset-count>

Given a Vim Golf-style sequence of keypresses as <vimkeys> (by default, yiW), lw looks at the console output of a previous command (going back <history-offset-count> commands, by default 1), executes the Vim keypresses against the console output of that command, then prints the contents of "0 (the yank register).

The cursor is positioned at G$ (end of last line) to start.

$ date
Wed Nov 11 11:38:48 EST 2015
$ lw
2015
$ lw 3ByiW 2
11:38:48
$ ls -l
total 16
-rw-r--r--  1 grib  staff  1811 Nov 11 13:47 README.md
-rwxr-xr-x  1 grib  staff  1445 Nov 11 13:48 lw
$ ./lw '?RE\nyiW'
README.md

And here's one more like my actual use case:

$ git status
On branch feature/rev-proxy-support
Your branch is up-to-date with 'origin/feature/rev-proxy-support'.
nothing to commit, working directory clean
$ lw 'gg$yiW'
feature/rev-proxy-support
$ git checkout master
$ git merge `lw 'gg$yiW' 3`

If you prefer to use a pipe instead of history, pass - as the history count:

$ ls -l | lw yiW - 
lw

Configuration

Configuration is via environment variables:

Variable	Default	Meaning
LW_PROMPT	^[^\$]*$	Regex matching prompt string
LW_HISTORY	~/.bash_history	Bash history file

Bash history setup

By default your ~/.bash_history is not written until you close the terminal. That's pretty useless! Add these lines to your ~/.bash_profile or equivalent:

export HISTCONTROL=ignoredups:erasedups  # no duplicate entries
export HISTSIZE=100000                   # big big history
export HISTFILESIZE=100000               # big big history
shopt -s histappend                      # append to history, don't overwrite it

# Save and reload the history after each command finishes
export PROMPT_COMMAND="history -a; history -c; history -r; $PROMPT_COMMAND"

Thanks to http://unix.stackexchange.com/questions/1288/preserve-bash-history-in-multiple-terminal-windows for the tip.

Caveats

• You have to be running tmux, otherwise grabbing the console output history without rerunning the last command is too much of a pain for me
• History gets pulled directly from ~/.bash_history or $LW_HISTORY since the history builtin doesn't work inside scripts.
• You have to have a sane Bash prompt that can be direct-hit by a regex. This probably means it's constant or doesn't change much (you're putting all that dynamic stuff in your tmux status line, right?).
• You are launching Vim every time you do this so it's not a performance tool.
• Patterns have to be escaped sort of crazily. The pattern is passed through shell's "printf" so you can embed things like \n and \022 (Ctrl-R, which is handy at times), but first your shell will try to expand \ escapes so you need to put another \ in front of your printf \ or enclose the whole thing in '' (which I have done above). Same for $.

Blame

Bill Gribble <[email protected]>