IRAF
User's Guide to Reducing Slit Spectra with IRAF, Phil Massey, Frank Valdes, Jeannette Barnes, April 1992
Guide to the Slit Spectra Reduction Task DOSLIT, Francisco Valdes, February 1993
Python
PyRAF provides a thin Python interface to IRAF. Here is an example of a longslit reduction pipeline written in PyRAF; note that it is heavily adapted to the file and header formats of the Palomar 200-inch Double Beam Spectrograph (DBSP).