Bash Word splitting IFS & word splitting
Example
See what, when and why if you don't know about the affiliation of IFS to word splitting
let's set the IFS to space character only:
set -x
var='I am
a
multiline string'
IFS=' '
fun() {
echo "-$1-"
echo "*$2*"
echo ".$3."
}
fun $var
This time word splitting will only work on spaces. The fun function will be executed like this:
fun I 'am
a
multiline' string
$varis split into 3 args.I,am\na\nmultilineandstringwill be printed
Let's set the IFS to newline only:
IFS=$'\n'
...
Now the fun will be executed like:
fun 'I am' a 'multiline string'
$varis split into 3 args.I am,a,multiline stringwill be printed
Let's see what happens if we set IFS to nullstring:
IFS=
...
This time the fun will be executed like this:
fun 'I am
a
multiline string'
$varis not split i.e it remained a single arg.
You can prevent word splitting by setting the IFS to nullstring
A general way of preventing word splitting is to use double quote:
fun "$var"
will prevent word splitting in all the cases discussed above i.e the fun function will be executed with only one argument.
