Chapter 16. Debug sendmail with -d
-d command-line switch allows you
sendmail’s inner workings in
detail. But note that
sendmail’s various debugging
switches differ from vendor to vendor and from version to version.
This chapter is specific to V8.13 sendmail.
These switches are perhaps best used with a copy of the
sendmail source by your side.
Also note that many of the internal details shown here will change as sendmail continues to evolve and improve.
What’s New with V8.13
Although there are no additional, useful debugging switch settings in V8.13, there is one new debugging command-line switch described next.
The New -D Debug File Switch
-D command-line switch is used
sendmail’s debugging output
(16.1[3ed]) into a file for later
examination. It is used as in the following example, where
file is the name of an existing or new
-D command-line switch (if used) must precede
-d switch on the same command-line, otherwise
the following error will print, and all debugging output will be
printed to the standard output (possibly causing you to miss seeing
-D file must be before -d
file specified with
-D must live in a directory that is writable by
the user running
sendmail. If the file does not
exist, it will be created. If the file already exists, it will be
silently appended to.
Extra care must be exercised when using the
command-line switch as root because the target file will be appended to, even if it is a symbolic link ...