Prepend to block of text, but ignore blank lines

Question

How to add the string 'export ' to the beginning of each line of this text, with emacs:

RBENV_VERSION="2.n.0"

AUTHORIZE_NET_API_LOGIN_ID=example
AUTHORIZE_NET_TRANSACTION_KEY=example

# Google Calendar Integration

# Google Calendar
GOOGLE_CLIENT_ID=example
GOOGLE_CLIENT_SECRET=example

# Live Mailchimp keys
MAILCHIMP_API_KEY=example

Answer 1

An answer to a different question would be to add

 _oldflags=$- ; set -a

as the first line of the file and

 [[ "$_oldflags" =~ a ]] || set +a ; unset _oldflags

which tells bash to export all the variables (the set -a) and restore the state of the "set -a" flag at the end. If you never use "set -a" then this can be simplified to adding "set -a" at the start and "set +a" at the end.

Answer 2

Here's one way:

(defun doit ()
  (interactive)
  (while (not (eobp))
    (beginning-of-line)
    (when (looking-at "[A-Z]")
      (insert "export "))
    (next-line)))

This will walk through the lines starting at the cursor until the end of the buffer, and if the line starts with a capital letter (per the given regular expression range), then it will prepend with the string.

To use, paste this into *scratch*, position your cursor after the last close paren, and hit C-x C-e to load the definition. Then go to the buffer with your text, position your cursor on the first line you want to change, and invoke with M-x doit.

Of course this could be enhanced to only work in a region, parameterize in various ways, etc.

Another option, if you don't want to define a function, is to adapt the approach into a macro like this:

1. Go to the first line you want to change in your buffer
2. Type C-x ( to start recording macro
3. Type C-a to go to beginning of line (don't skip this step even if you're already at the beginning of the line)
4. Type M-: to bring up the "Eval:" prompt and enter (when (looking-at "[A-Z]") (insert "export "))
5. Type C-n to go to the next line
6. End the macro with C-x )
7. Repeat the macro a bunch of times: C-u 10 C-x e