Advanced Bash−Scripting Guide

Advanced Bash−Scripting Guide
CopyArray=CpArray_Mac
# Statement Builder
Hype()
{
# Hype the array named $1.
# (Splice it together with array containing "Really Rocks".)
# Return in array named $2.
local −a TMP
local −a hype=( Really Rocks )
}
$($CopyArray $1 TMP)
TMP=( ${TMP[@]} ${hype[@]} )
$($CopyArray TMP $2)
declare −a before=( Advanced Bash Scripting )
declare −a after
echo "Array Before = ${before[@]}"
Hype before after
echo "Array After = ${after[@]}"
# Too much hype?
echo "What ${after[@]:3:2}?"
declare −a modest=( ${after[@]:2:1} ${after[@]:3:2} )
# −−−− substring extraction −−−−
echo "Array Modest = ${modest[@]}"
# What happened to 'before' ?
echo "Array Before = ${before[@]}"
exit 0
−−
Arrays permit deploying old familiar algorithms as shell scripts. Whether this is necessarily a good idea is left
to the reader to decide.
Example 26−6. An old friend: The Bubble Sort
#!/bin/bash
# bubble.sh: Bubble sort, of sorts.
# Recall the algorithm for a bubble sort. In this particular version...
# With each successive pass through the array to be sorted,
#+ compare two adjacent elements, and swap them if out of order.
# At the end of the first pass, the "heaviest" element has sunk to bottom.
# At the end of the second pass, the next "heaviest" one has sunk next to bottom.
# And so forth.
# This means that each successive pass needs to traverse less of the array.
Chapter 26. Arrays 299