The -b switch tells sendmail in what mode to operate . For example, sendmail can "become" a daemon listening for incoming SMTP connections, or it can run in a mode that tells it to simply print the contents of the queue and exit. The form of the -b switch is: -b mode If mode is more than a single letter, all but the first letter is silently ignored. If the mode is missing or not one of those allowed, sendmail prints the following error message and exits: Invalid operation mode bad letter here If the -b command-line switch is omitted altogether, the default mode becomes -bm (deliver mail and exit). Beginning with V8.7 sendmail , the letter that selected the operating mode is assigned at startup to the ${opMode} sendmail macro (${opMode}). |