Bash variables without double quotes can give surprising results. The special characters inside a variable when not double quoted, gets interpreted by bash. Few points to note:
- echo will pint newline as space if variable is not quotes.
- bash for loop will treat a string with spaces/newlines as multiple values delimited by space.
Here are some code examples
ls outcome – echo variable with quote vs without quote
#!/bin/bash mkdir -p testdir cd testdir; touch file1.txt; touch file2.txt a=$(ls) echo '===echo $a [newlines not expected]===' echo $a echo '===echo "$a" [newlines expected]===' echo "$a"
===echo $a [newlines not expected]=== file1.txt file2.txt ===echo "$a" [newlines expected]=== file1.txt file2.txt
Env: GNU bash, version 4.2.46
ls outcome – for loop iteration on variable with quote vs without quote
#!/bin/bash mkdir -p testdir cd testdir; touch file1.txt; touch file2.txt a=$(ls) echo '===iterating over $a===' for i in $a do echo "val: $i" done echo '===iterating over "$a"===' for i in "val: $a" do echo "$i" done
===iterating over $a=== val: file1.txt val: file2.txt ===iterating over "$a"=== val: file1.txt file2.txt
Env: GNU bash, version 4.2.46
