HowTo's

Do you ever spend 20 minutes figuring out the perfect way to do some arcane task on the command line, only to forget it and need it again in a month? I do. A lot.

I started keeping a directory with little plain text documents that had the command line I wanted inside them. I recently uploaded them to my static site and wrote a script to use them easier.

It's real simple, just download the howto bash script in the following directory http://static.velvetcache.org/howtos/ and place it in your path. Now make a directory for your HowTo's somewhere and put the whole path into a file in your home directory called ".howto".

You should be able to call $ howto --sync and it will pull down a tar of the most current files, then expand it into your HowTo directory.

If you download the howto.tar.gz by itself, be warned that it is a tar bomb and will rudely scatter its files all over your directory.

Lastly, onceyou have some HowTo's installed, just use $ howto -l to list out the possible choices, then $ howto print-unix-timestamp, replacing "print-unix-timestamp" with the name or number of the HowTo you want.

Below is the howto shell script, because I like including code in my posts whenever I can.

#!/bin/bash

function printUsage {
	echo "Usage: howto [-l | --list] file-name"
	exit 1
}

if [ $# -ne 1 ]; then
	printUsage
fi

if [ ! -f ~/.howto ]; then
	echo "No .howto file found in your home directory!"
	exit 1
fi

HOWTODIR=$(cat ~/.howto)

if [ "$1" == "--sync" ]; then
	LRECENT=$(cat $HOWTODIR/CURRENT)
	SRECENT=$(wget -O - http://static.velvetcache.org/howtos/CURRENT 2> /dev/null)
	if [ $? -ne 0 ]; then
		echo "Can't contact download server."
		exit 1
	fi
	if [ "$LRECENT" != "$SRECENT" ]; then
		cd $HOWTODIR
		if [ $? -ne 0 ]; then
			echo "Can't change to the HowTo directory."
			exit 1
		fi
		wget -O howtos.tar.gz http://static.velvetcache.org/howtos/howtos.tar.gz
		if [ $? -ne 0 ]; then
			echo "Can't download new files."
			exit 1
		fi
		tar -zxf howtos.tar.gz
		if [ $? -ne 0 ] ; then
			echo "Can't untar the updates."
			exit 1
		fi
		rm -f howtos.tar.gz
		exit 0
	else
		echo 'Nothing new to download.'
		exit 0
	fi
fi

if [ "$1" == "--list" ] || [ "$1" == "-l" ]; then
	COUNTER=0
	for howto in `ls $HOWTODIR`; do 
		echo "$COUNTER $howto"
		COUNTER=$(expr $COUNTER + 1)
	done	
	exit 0
fi

echo $1 | grep '^[0-9][0-9]*$' > /dev/null 2>&1
if [ $? -eq 0 ]; then
	COUNTER=0
	for howto in `ls $HOWTODIR`; do
		if [ $COUNTER -eq $1 ]; then
			cat $HOWTODIR/$howto
			exit 0
		fi
		COUNTER=$(expr $COUNTER + 1)
	done
	echo 'That HowTo was not found.'
	exit 1
elif [ ! -f "$HOWTODIR/$1" ]; then
	echo 'That HowTo was not found.'
	exit 1
fi

cat $HOWTODIR/$1

exit 0