36.2 Command-Line Switches

Command-line switches are command-line arguments that begin with a - character, and precede the list of recipients (if any). The forms for command-line switches, where X is a single letter, are:

-X           


 Boolean switch



-Xarg        


 switch with argument

All switches are single letters. The complete list is shown in Table 36.2 .

Table 36.2: Command-Line Switches

Switch		Version	Description
-B	Section 36.7.1, -B	V8.1 and above	Specify message body type
-b	Section 36.7.2, -b	All versions	Set operating mode
-ba	Section 36.7.3, -ba	Not V8.1- V8.6	Use ARPAnet/Grey Book protocols
-bD	Section 36.7.4, -bD	V8.8 and above	Run as a daemon, but don't fork
-bd	Section 36.7.5	All versions	Run as a daemon
-bH	Section 36.7.6	V8.8 and above	Purge persistent host status
-bh	Section 36.7.7, -bh	V8.8 and above	Print persistent host status
-bi	Section 24.5.1	All versions	Initialize alias database
-bm	Section 36.7.9, -bm	All versions	Be a mail sender
-bp	Section 23.4	All versions	Print the queue
-bs	Section 36.7.11, -bs	All versions	Run SMTP on standard input
-bt	Section 38.1, "Overview"	All versions	Rule testing mode
-bv	Section 36.7.13, -bv	All versions	Verify: don't collect or deliver
-bz	Section 36.7.14, -bz	Not V8	Freeze the configuration file
-C	Section 36.7.15, -C	All versions	Location of configuration file
-c	Section 34.8.29, HoldExpensive (c)	Deprecated	Set HoldExpensive (c) option to true
-d	Section 37.1, "The Syntax of -d"	All versions	Enter debugging mode
-E	Section 36.7.18, -E	Sony NEWS only	Japanese font conversion
-e	Section 34.8.24, ErrorMode (e)	Deprecated	Set the ErrorMode (e) option's mode
-F	Section 36.7.20, -F	All versions	Set the sender's full name
-f	Section 36.7.21, -f and -r	All versions	Set sender's address
-h	Section 36.7.22, -h	Deprecated	Minimum hop count
-I	Section 36.7.23, -I	Deprecated	Synonym for -bi
-i	Section 36.7.24, -i	Deprecated	Set the IgnoreDots (i) option to true
-J	Section 36.7.25, -J	Sony NEWS only	Japanese font conversion
-M	Section 31.2, "Command-Line Definitions"	V8.7 and above	Define a macro on the command line
-m	Section 34.8.39, MeToo (m)	All versions	Set the MeToo (m) option to true
-N	Section 36.7.28, -N	V8.8 and above	Specify DSN NOTIFY information
-n	Section 24.6, "Prevent Aliasing with -n"	All versions	Don't do aliasing
-O	Section 34.1, "Command-Line Options"	V8.7 and above	Set a multicharacter option
-o	Section 34.1	All versions	Set a single-character option
-p	Section 36.7.32, -p	V8.1 and above	Set protocol and host
-q	Section 23.6.1	All versions	Process the queue
-R	Section 36.7.34, -R	V8.8 and above	DSN what to return on a bounce
-r	Section 36.7.21	Deprecated	Synonym for -f
-s	Section 34.8.59, SaveFromLine (f)	Deprecated	Set the SaveFromLine (f) option to true
-T	Section 34.8.52, QueueTimeout (T)	Deprecated	Set QueueTimeout (T) option
-t	Section 36.7.38, -t	All versions	Get recipients from message header
-U	Section 36.7.39, -U	V8.8 and above	This is the initial MUA to MTA submission
-V	Section 36.7.40, -V	V8.8 and above	Specify the ENVID string
-v	Section 36.7.41	All versions	Run in verbose mode
-X	Section 26.4, "Log Transactions with -X"	V8.1 and above	Log transactions
-x	Section 36.7.43, -x	V8.2 and above	Ignored

Some switches are called Boolean because they are either true or false. The -v switch, for example, is Boolean because it puts sendmail into verbose mode if it is present (true). If it is absent (false), sendmail does not run in verbose mode.

Some switches take arguments. The -C switch, for example, tells sendmail where to find its configuration file. When a switch takes an argument, the argument may immediately follow the letter or be separated from it with whitespace: [2]

[2] Prior to V8 sendmail , whitespace was not allowed between the letter and the argument.

-Ctest.cf          
 good

-C test.cf         
 also good

The only exception to this rule is the -d command-line switch (set debugging mode). It may not have whitespace between the letter and the arg .

Some switches, such as -q (process the queue), can either be Boolean or take an argument:

-q                  boolean
-q1h                with argument

The position of switches in the command line is critical. If any follow the list of recipients, they are wrongly taken as mail addresses and lead to bounced mail. But the order in which switches appear prior to the recipients is not important. That is, they may appear in any order without changing the behavior of sendmail .

An undefined switch letter causes the following error to be printed and sendmail to immediately exit:

sendmail: illegal option - 
bad letter here

The special switch -- can be used to delimit the switches from the list of recipients:

% 

/usr/lib/sendmail -- -jim

Here, the recipient is -jim . To prevent the - of -jim from being wrongly interpreted as indicating a switch, the special switch -- is used to mark the end of all switches. [3]

[3] Under pre-V8 sendmail , recipient names could never begin with a -C , -b , -d , -q , or -Z . If any did, they were wrongly interpreted as switches during preprocessing.