bashtag-save

Introduction

Inspired by this (HackerNews discussion here). The idea is to use bash comments on the command line similarly to Twitter hashtags to leave strings in your history that you can find easily with ctrl+r. We'll affectionately refer to these as "bashtags". Here's an example:

jpk@truth:~$ avconv -f alsa -ac 1 -i hw:1,0 -f x11grab -s 356x464 -i :0.0+121,443 -acodec libvo_aacenc -vcodec libx264 -preset fast -qp 0 -r 30 -async 30 video.mp4 #longassffmpegcommand

We just stuff the bashtag "#longassffmpegcommand" at the end of the command line so when we ctrl+r, 'longass' reverse search finds your command:

(reverse-i-search)`longass': avconv -f alsa -ac 1 -i hw:1,0 -f x11grab -s 356x464 -i :0.0+121,443 -acodec libvo_aacenc -vcodec libx264 -preset fast -qp 0 -r 30 -async 30 video.mp4 #longassffmpegcommand

This is a nifty idea, but it begs the question: If you want to call up your huge command regularly, why not just put it in a script? Good question. That's what this joint is for.

Using bashtag-save

Adding the bashtag-save function to $PROMPT_COMMAND makes your shell aware of commands you type that have been tagged with tags starting with "#save:". Like so:

jpk@truth:~$ avconv -f alsa -ac 1 -i hw:1,0 -f x11grab -s 356x464 -i :0.0+121,443 -acodec libvo_aacenc -vcodec libx264 -preset fast -qp 0 -r 30 -async 30 video.mp4 #save:longassffmpegcommand
(avconv does stuff...)
jpk@truth:~$ ls -l ./scripts/saved/
total 4
-rwxrwxr-x 1 jpk jpk 198 Jun 30 15:57 longassffmpegcommand.sh
jpk@truth:~$ cat ./scripts/saved/longassffmpegcommand.sh 
#!/usr/bin/env bash
avconv -f alsa -ac 1 -i hw:1,0 -f x11grab -s 356x464 -i :0.0+121,443 -acodec libvo_aacenc -vcodec libx264 -preset fast -qp 0 -r 30 -async 30 video.mp4 #save:longassffmpegcommand
jpk@truth:~$ ./scripts/saved/longassffmpegcommand.sh
(avconv does stuff again...)
jpk@truth:~$ 

So tagging something with #save:scriptname will save the command to a script at ~/scripts/saved/scriptname.sh. You can leave it there for later, go edit it to build a more complex script around the command, whatever.

Installation

First, clone this repo or download and save bashtag-save.sh somewhere. Next, you should see something like this in your ~/.bashrc:

case "$TERM" in
xterm*|rxvt*)
    PROMPT_COMMAND='echo -ne "\033]0;${USER}@${HOSTNAME}: ${PWD/$HOME/~}\007"'
    ;;
*)
    ;;
esac

You'll want to source bashtag-save.sh from wherever you saved it, then add the bashtag-save function to PROMPT_COMMAND. You probably don't want to lose whatever's already there, though. So make another function nearby that will do whatever you already have in PROMPT_COMMAND, but also call bashtag-save. You should end up with something like this:

source path/to/bashtag-save.sh
function prompt_commands {
    echo -ne "\033]0;${USER}@${HOSTNAME}: ${PWD/$HOME/~}\007"
    bashtag-save
}
case "$TERM" in
xterm*|rxvt*)
    PROMPT_COMMAND='prompt_commands'
    ;;
*)
    ;;
esac

Last, you'll want to create the directory where the scripts are saved. The default is ~/scripts/saved/.

Customization

The bashtag-save function is really simple. Open bashtag-save.sh and give it a look. To change the tag prefix the function uses to recognize if a command should be saved or not, just change the save_tag_prefix variable (the default is #save:). To change the path were scripts are saved, change the script_path variable (the default is ~/scripts/saved/). To change what gets written to the script, change the stuff between the EOLs on the line that starts with cat > $script_file (the default is just a shebang line, then the command).