How would I write a one-off boot script?

Question

I would like to run a script that would run only on the first boot. For example, Tom could use it to generate unique SSH certs in How can I copy the same image to many SDs?.

I was thinking that I could get the script to delete itself, is this a good idea?

Boot scripts are handled differently by different distributions. So re-tagging with what distro you're using would be helpful. — Jivings, Jul 17 '12 at 12:56
That would have to be a separate answer for each distro then. — Jivings, Jul 17 '12 at 12:58

score 3 · Answer 1 · answered Jul 17 '12 at 13:08

3

Why should it be a bad idea? Check if your script was succesful and put as last command

rm -f $0

answered Jul 17 '12 at 13:08

macrojames

96
3

I couldn't think of a reason! – Alex Chamberlain Jul 17 '12 at 13:10
But check if everything went well. Raspbmc does not and tried to boot a zero-byte root filesystem – macrojames Jul 17 '12 at 13:11

score 1 · Answer 2 · answered Jul 17 '12 at 16:29

Why not check if the output exists before you try to write it? Here is some pseudo-code:

if( file_exists( '/etc/myfile' ) ) {
    delete( $SELF );
    exit( 0 );

} else {
    create_file( '/etc/myfile' );
}

It makes sure your output exists before it deletes itself. This way, you can be (more) sure that your script did its job (or wasn't required for some reason).

How would I write a one-off boot script?

2 Answers2