Bash Lessons: Arrays

gistfile1.txt

$ # Arrays...
$
$ foo=( word 'this has spaces' )
$
$ # Unless you treat it like an array, 
$ # it just behaves like a scalar with
$ # the first element of the array.
$ echo $foo
word
$ echo ${#foo}
$ 4
$
$ # Okay, let's treat it like an array.
$ echo ${#foo[*]}
2
$ echo ${foo[*]}
word this has spaces
$ echo ${foo[@]}
word this has spaces
$
$ # Hmm. Is there a difference between those?
$ for item in ${foo[*]}; do echo $item; done
word
this
has
spaces
$ for item in ${foo[@]}; do echo $item; done
word
this
has
spaces
$
$ # Actually there is a difference, but you'll
$ # need quotes to see it. 
$ for item in "${foo[*]}"; do echo $item; done
word this has spaces
$ for item in "${foo[@]}"; do echo $item; done
word
this has spaces
$
$ # Arrays support appending as you might expect
$ foo+=( 'appended' )
$ echo "${foo[@]}"
word this has spaces appended
$
$ # You can index from the end too,
$ # but make sure you aren't off-by-one
$ echo ${foo[-1]}
appended