Usefulness of word splitting

There are some cases where word splitting can be useful:

Filling up array:

arr=($(grep -o '[0-9]\+' file))

This will fill up arr with all numeric values found in file

Looping through space separated words:

words='foo bar baz'
for w in $words;do
    echo "W: $w"
done

Output:

W: foo
W: bar
W: baz

Passing space separated parameters which don’t contain white spaces:

packs='apache2 php php-mbstring php-mysql'
sudo apt-get install $packs

or

packs='
apache2
php
php-mbstring
php-mysql
'
sudo apt-get install $packs

This will install the packages. If you double quote the $packs then it will throw an error.

Unquoetd $packs is sending all the space separated package names as arguments to apt-get, while quoting it will send the $packs string as a single argument and then apt-get will try to install a package named apache2 php php-mbstring php-mysql (for the first one) which obviously doesn’t exist

See what, when and why for the basics.