lw: A Shell repository from bgribble

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