[pdkl95]

Traditionally, this would be a job for m4:

    $ cat examples/config.yaml.in 
    user: USERNAME
    password: ifelse(PASSWORD,`PASSWORD',`defaultpass',PASSWORD)
    files:
    patsubst(esyscmd(`ls'), `.+$', `  - \&')

    $ m4 -DUSERNAME=somebody examples/config.yaml.in
    user: somebody
    password: defaultpass
    files:
      - README.m4
      - examples
      - sempl