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The Command Line
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36.6 Pitfalls

  • Prior to V8 sendmail , if the list of recipients contained an address that began with any of the prescanned switches, sendmail would wrongly view that recipient as a switch during its prescan phase. For example, mail to joe, bill, -Cool caused sendmail to try to use a file named ool as its configuration file.

  • Command-line switches must precede recipient addresses. Switches that are mixed in with recipient names are treated as recipient addresses.

  • Most versions of sendmail (including IDA and some versions of BSD but excluding SunOS and V8) syslog (3) a warning if the frozen configuration file doesn't exist. This can be annoying at sites that intentionally choose not to use a frozen configuration file.

  • Prior to V8 sendmail , unknown command-line switches were silently ignored. Therefore sending mail from a shell script could fail for reasons that were difficult to find. For example, specifying the preliminary hop count wrongly with -j , instead of correctly with -h , caused your presetting of the hop count to be silently ignored.

  • Some old BSD and SunOS versions of sendmail set the default sender's full name from the environmental variable NAME even when running as a daemon or when processing the queue. This can lead to the superuser's full name occasionally showing up wrongly as a sender's full name. IDA and V8 sendmail clear the full name in -bd and -q modes but use different methods. To prevent this problem under other versions of sendmail , the env (1) program can be used to clean up the environment passed to sendmail :

    env - /usr/lib/sendmail -bd -q1h

  • V8 sendmail uses getopt (3) to parse its command-line arguments so that a switch and its argument may have whitespace between them without harm:

    -C configfile

    But for bizarre historical reasons the -d switch differs. There may never be space between the -d and its arguments:

    -d 0.4

    If there is space between them, the argument (here, 0.4 ) is taken to be a recipient name.

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