The Uncarved Block

Sometimes it's useful to have shell functions that can be used both from within my current shell and sourced inside scripts which I write. To achieve this is fairly easy if you arrange things according to a simple convention. What I do is to make a directory called "lib" in my homedir, and put each function into a seperate file in there that has the same name as the function.

For example, I wrote a small function to print the name of the file in a given directory that has most recently been modified. To make this more generic, I got it to print the n-th from last, rather than specifically the last. So I make a small file called ~/lib/printlastfile containing the following:

# vim: set syn=zsh:

#if no args are supplied, print the last filename from $TMP
#if one arg, print the n-th from last filename from $TMP
#if two args, the second arg is the name of a dir to use instead of TMP
printlastfile()
{
    RANK=${1:-1}
    #expand $TMPDIR and append a trailing slash if it doesn't have one
    DIR=$( echo ${2:-${TMPDIR:-'/tmp/'}} | sed 's,[^/]$,&/,' )

    ls -t "${DIR}"* | sed -n "${RANK}p;${RANK}q"
}

So any time I want that function I can just source that file. Now say I want an executable that runs printlastfile. I could make ~/bin/printlastfile as follows:

#!/bin/zsh
. ~/lib/printlastfile
printlastfile "${1}" "${2}"

... but that gets a bit tedious when you have a few of these things so I made one generic executable that for any function, will source the function and then run it. I call it libsquiggle because it turns things which are in squiggle/lib into executables and it looks like this:

#!/usr/bin/env zsh

MYNAME="${0:t}"
. "${HOME}/lib/${MYNAME}"

$MYNAME "$@"

So I make an executable called libsquiggle that looks like that and for any function in ~/lib that I want to work as an executable I make a symlink in ~/bin called the name of the function and pointing to ~/bin/libsquiggle. Thus:

ls -l =printlastfile

lrwxrwxrwx  1 sean sean 11 Oct  5  2005 /home/huntse/bin/printlastfile -> libsquiggle