Advanced Bash−Scripting Guide

Advanced Bash−Scripting Guide
echo −n "area2[0] = "
echo ${area2[0]}
# Aha, zero−based indexing (first element of array is [0], not [1]).
echo −n "area2[1] = "
echo ${area2[1]} # [1] is second element of array.
# −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
echo; echo; echo
# −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
# Yet another array, "area3".
# Yet another way of assigning array variables...
# array_name=([xx]=XXX [yy]=YYY ...)
area3=([17]=seventeen [24]=twenty−four)
echo −n "area3[17] = "
echo ${area3[17]}
echo −n "area3[24] = "
echo ${area3[24]}
# −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
exit 0
Bash permits array operations on variables, even if the variables are not explicitly
declared as arrays.
string=abcABC123ABCabc
echo ${string[@]}
echo ${string[*]}
echo ${string[0]}
echo ${string[1]}
# abcABC123ABCabc
# abcABC123ABCabc
# abcABC123ABCabc
# No output!
# Why?
echo ${#string[@]} # 1
# One element in the array.
# The string itself.
# Thank you, Michael Zick, for pointing this out.
Once again this demonstrates that Bash variables are untyped.
Example 26−2. Formatting a poem
#!/bin/bash
# poem.sh
# Lines of the poem (single stanza).
Line[1]="I do not know which to prefer,"
Line[2]="The beauty of inflections"
Line[3]="Or the beauty of innuendoes,"
Line[4]="The blackbird whistling"
Line[5]="Or just after."
# Attribution.
Attrib[1]=" Wallace Stevens"
Chapter 26. Arrays 293