If I may... I don't think we're all on the same page. I say that because the bash shell does not
have a command or built-in named push nor unshift. Perl does
have both of those commands.
So, I think ajhunter wants a one-liner Perl script--even though it was not specified in the original post. I don't care for Perl. So I can't help beyond giving this link: Perl's env module documentation
. Read it and look at the short examples.
Even so, following the examples given on that page will not make the changes permanent. As udaman said, the appropriate entry in ~/.profile (or any other appropriate startup file for your shell) will need to be made/updated.