begins to run, it performs a preliminary scan
of its command-line arguments. It does this because some actions
need to be performed before its configuration file is read.
After the command-line switches are prescanned, but before they are processed in full, sendmail performs two important internal tasks.
The environmental variables that are given to sendmail when it is first run are ignored. When running delivery agents, sendmail provides a small, customized environment. See Section 22.2, "The Environment" for a detailed discussion of this step.
Certain macros are next declared and assigned values. The
Command-line switches are processed by
appear in the command line, from left to right.
The processing of switches ends when an argument is found that lacks
The fact that the configuration file is read after the command-line switches are processed can lead to some confusion. Some, but not all, command-line switches can overwrite some configuration file commands. Since there is no general rule, we describe the behavior of each item (such as macros and options) in a chapter dedicated to each.
The final step sendmail undertakes in processing its command line is gathering the list of recipients. Each recipient (or list of recipients if more than one is contained in a single command-line argument) is fully processed for delivery, and any error messages are printed before delivery is actually undertaken.