mail_pipe(1M)         UNIX System V(Essential Utilities)          mail_pipe(1M)


NAME
      mailpipe - invoke recipient command for incoming mail

SYNOPSIS
      mailpipe [ -x debug_level ] -r recipient -R path_to_sender -c
      content_type -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 debug_level    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 path_to_sender The return address to the message's originator.
      -c content_type   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].





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mail_pipe(1M)         UNIX System V(Essential Utilities)          mail_pipe(1M)


FILES
     /etc/passwd      to identify sender and locate recipients
     /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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