mail_pipe(1M)                  DG/UX R4.11MU05                 mail_pipe(1M)


NAME
       mailpipe - invoke recipient command for incoming mail

SYNOPSIS
       mailpipe [ -x debuglevel ] -r recipient -R pathtosender -c
       contenttype -S subject

DESCRIPTION
       When a new mail message arrives, the mail command first checks if the
       recipient's mailbox indicates that the message is to be forwarded
       elsewhere (to some other recipient or as the input to some command).
       If the message is to be piped into a recipient-specified command,
       mail invokes mailpipe to do some validation and then execute the
       command in the context of the recipient.

       Command-line arguments are:
       -x debuglevel    Turn on debugging for this invocation. See the
                         description of the -x option for the mail command
                         for details.
       -r recipient      The recipient's login id.
       -R pathtosender The return address to the message's originator.
       -c contenttype   The value of the Content-Type: header line in the
                         message.
       -S subject        The value of the Subject: header line in the
                         message if present.

       mailpipe is installed as a setuid-to-root process, thus enabling
       itself to change it's user and group ids to that of the recipient as
       necessary.

       When invoked, mailpipe performs the following steps (if a step
       fails, the exit code is noted as [N]):
       -  Validate invocation arguments [1].
       -  Verify that recipient name is <= 14 characters long [2].
       -  Verify that the setgid flag for the recipient mailbox is set [3].
       -  Open /var/mail/recipient [4].
       -  Verify that recipient's mailbox starts with the string Forward to
          [5].
       -  Find pipe symbol indicating start of command string in recipient
          mailbox [6].
       -  Find entry for recipient in /etc/passwd [7].
       -  Set gid to recipient's gid [8].
       -  Set uid to recipient's uid [9].
       -  Change current directory to recipient's login directory [10].
       -  Allocate space to hold newly exec'ed environment for recipient
          command [11].
       -  Parse the recipient command, performing any %keyword expansions
          required.  See the `Forwarding mail' section of mail(1), for more
          information regarding %keyword substitutions [12].
       -  Execute recipient command [13 if exec fails, otherwise exit code
          from recipient command itself].

FILES
        /etc/passwd      to identify sender and locate recipients
        /etc/TIMEZONE    to set TZ for mail forwarding
        /var/mail/recipient
                         incoming mail for recipient; that is, the mail file
        /tmp/MLDBG*      debug trace file
        /usr/lib/mail/mailpipe
                         mail_pipe program

SEE ALSO
       mail(1), notify(1), vacation(1)


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