Question

I have some lines like below:

aaa
bbb
ccc
ddd

I want them to be changed like this:

aaa=$aaa
bbb=$bbb
ccc=$ccc
ddd=$ddd

so I use the following command to do it in vim, but I got an error

:s/\(\^*\)/\1=\$\1/

and I realized the \1 here could not be used twice, then how should I do this?

Answer 1

The back reference \1 can be used as many times as you wish, but you have another problem. Your regex should look like that:

:%s/^\(.*\)/\1=\$\1/

Explanation: the % tells vim to replace on all lines; ^ as a mark for the beginning of line should be the first character in your regex and should not be escaped. The .* means “any character any number of times”. However, the original expression \(\^*\) will look for any number of repeats of the literal character ^ (including none).