head outputting text on single line without linebreaks

Question

My command is this:

df=$(echo `df -h | head -3`)
echo $df

I would expect it to display the first three lines of df -h output as such:

Filesystem      Size  Used Avail Use% Mounted on
/abc/asdf       16G   5.6G  9.4G  38% /
abcd            1.9G   12K  1.9G   1% /dev

Instead, it outputs this:

Filesystem Size Used Avail Use% Mounted on /abc/asdf 16G 5.6G 9.4G 38% / abcd 1.9G 12K 1.9G 1% /dev

• How can I make sure that echo $df outputs the newline character in my shell script?
• What is causing the echo to ignore the newline character from head?

Answer 1

Quote the variable to prevent word splitting:

echo "$df"

99% of the time you should quote variables when you use them. Only use variables unquoted if you really want them to be subject to word splitting and globbing. There are some occasions where quotes are not needed (e.g. assignments like a=$b), but the redundant quotes won't hurt.

I just notieced that you're also using echo inside the $(). I'm not sure why, but you also need quotes there:

df=$(echo "`df -h | head -3`")

But you don't need echo, you can just write:

df=$(df -h | head -3)