I am new to shell scripting, and I’ve recently encountered something I didn’t comprehend.
What is the difference between these two scripts:
Script 1:
COLORS="RED YELLOW GREEN"
for i in $COLORS
do
echo $i
done
Script 2:
for i in "RED YELLOW GREEN"
do
echo $i
done
From my perspective, they should have the same output, but they don’t.
Output:
Script 1:
RED
YELLOW
GREEN
Script 2:
RED YELLOW GREEN
Thanks a lot 🙏
>Solution :
The difference comes down to quoting and variable expansion rules.
After variable expansion, the quotes in the first example are gone and this is equivalent to a loop over 3 elements:
for i in RED YELLOW GREEN
do
echo $i
done
whereas the second example is a loop over one element that happens to be a string containing spaces:
for i in "RED YELLOW GREEN"
do
echo $i
done
If you want to get the second behavior while using a variable, you need to add a level of quoting around the variable expansion, ie:
COLORS="RED YELLOW GREEN"
for i in "$COLORS"
do
echo $i
done