Question

The following line:

`eval echo echo $VAR=\\$$VAR` >> $FILE

will output to a file called $FILE:

FOO=value_of_full
BAR=value_of_bar

I want to I output quotes, such as in:

FOO="value_of_full"
BAR="value_of_bar"

I have already tried using \" and "" but both did not work as I expected.

Answer 1

It is your eval that is swallowing up your quotes.

You can use indirect variable referencing with bash >= 2.0 to alleviate the need for the eval:

echo "${VAR}=\"${!VAR}\"" >> $FILE

Unfortunately, double (or triple…) dereferences arn’t supported, so you can’t do ${!!VAR} or ${!${!VAR}} — you still have to resort to the eval method for those. But I don’t think you need that in this case.

If you really do want to use eval, then you will have to double-escape your escapes, like this:

eval echo "$VAR=\\\"\$$VAR\\\"" >> $FILE

Or, if you really need the extra level of execution (as in your example above), then you need to triple-escape your escapes!

`eval echo echo $VAR=\\\\\"\\$$VAR\\\\\"` >> $FILE

Personally, I prefer the 1st method 🙂