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Comments in .mc Files

  • m4 sees files as streams, but recognizes newline characters as significant
  • Normally, # sets off a comment, as in many languages
  • But...! The macro files used by Sendmail disable this so that comments beginning with "#" can be passed through to sendmail.cf
  • Sample .mc files for Sendmail use divert(-1) and divert(0) to comment out blocks of text. This is dangerous! May have unexpected side effects.
  • Best to use dnl (delete to newline) macro for all comments and at ends of all commands