Contents:
The Syntax of -d
Debugging Behavior
Interpreting the Output
Pitfalls
Reference in Numerical Order
The
sendmail
program offers a command-line switch for investigating and solving mail problems. The debugging
-d
switch allows you to observe
sendmail
's inner workings in detail.
The form for the
-d
command-line switch is
-dcategory.level,category.level,....
-dANSI V8.8 and above
The
-d
may appear alone, or it may be followed by one or more
category.level
pairs separated by commas or, beginning with V8.8, by the word ANSI. We cover the
category.level
pairs first then ANSI.
The
category
limits debugging to an aspect of
sendmail
(such as queuing or aliasing). The
level
limits the verbosity of
sendmail
(with low levels producing the least output).
The
category
is either a positive integer or a range of integer values specified as
first-last
When
category
is a range,
first
is a positive integer that specifies the first category in the range. It is followed by a hyphen character (
-
) and then
last
, a positive integer that specifies the last category in the range. The value of
first
must be less than the value of
last
, or the range will be ignored.
The level is a positive integer. A level of 0 causes sendmail to produce no output for the category.
When the
-d
is specified with neither
category
nor
level
, an internal
sendmail
default is used:
0-99.1
This default causes sendmail to set all the categories, from zero through 99 inclusive, to a level of 1.
When
category
is included but
level
is omitted, the value for
level
defaults to 1. When a dot (
.
) and
level
are included, but
category
is omitted, the value for
category
defaults to 0.
The maximum value that may be specified for a single
category
is 99. Any value specified above the maximum is reduced to the maximum. The maximum value for
level
is that of an
unsigned char
(255 decimal). Nondigits for the
category
or range evaluate to zero. Nondigits for the
level
evaluate to 1.
The
level
specifies the maximum amount of verbose output to produce. All levels below the
level
specified also produce output.
The expression that produces the maximum debugging output is
-d0-99.127
But beware that debugging levels of 100 or greater may cause
sendmail
to modify its behavior. (For example, one category at such a high level causes
sendmail
to not remove its temporary files.) For this reason,
-d0-99.99
is the maximum level recommended.
Debugging can be turned on from the command line and from within
-bt
rule-testing mode (see
Section 38.7, "Add Debugging for Detail"
). If
sendmail
is wrongly compiled with SMTPDEBUG defined (see
Section 18.8.42, SMTPDEBUG
), debugging can be turned on via an SMTP DEBUG command.
Beginning with V8.8 sendmail , a special debugging word can be specified at the command line to cause debugging output to become clearer:
-dANSI V8.8 and above
ANSI is case sensitive and must be the only argument following the
-d
. If you wish to combine it with other debugging switches, you must specify them separately:
-dANSI -d0.4
ANSI causes defined macros, class macros, and operators to be displayed in reverse video:
R $+ $# local $: $1
This is truly a "hack." The escape code to highlight characters is hard-coded into sendmail . Your display must support ANSI standard escape sequences for this to work. There is no plan to use standard library support for this "aid to rule-set hackers."