Shell Script - save substring to variable

Question

Hey,

A really simple shell script question. I have a file with something like this:

var "aaaaa"
var "bbbbb"
...

Now, how can I assign the string in quotes to a variable? This is what I have now (but I'm missing the assign part...):

while read line
do
  echo $line | cut -d" " -f3
done

which prints what I want... how do I save it to a variable?

Thanks

Answer 1

Depends on a shell.

Bourne and derivatives, you do

my_var_name=expression

C shell and derivatives, you do

setenv my_var_name expression

If you want to save the output of a command (e.g. "cut xyz"), you use backticks operator as your expression:

my_var_name=`echo $line | cut -d" " -f3`

I think that bash also supports $() but not sure of a difference from backticks - see section 3.4.5 from http://tldp.org/LDP/Bash-Beginners-Guide/html/sect_03_04.html

Answer 2

my_var=$(echo $line | cut -d" " -f3)

You need to execute the command. That is what the $() is for.

Answer 3

you don't have to use external cut command to "cut" you strings. You can use the shell, its more efficient.

while read -r a b
do
  echo "Now variable b is your quoted string and has value: $b"
done <"file"

Or

while read -r line
do
  set -- $line
  echo $2
done <"file"