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eof without closing the pipe

by csorensen (Beadle)
on Jun 30, 2000 at 00:38 UTC ( #20488=perlquestion: print w/ replies, xml ) Need Help??
csorensen has asked for the wisdom of the Perl Monks concerning the following question:

the problem: I need to send a bunch of email without using cc, bcc or anything like that.
I would like to find a way to send an email message without closing the pipe


unfortunately I have no idea how to do this so I am stuck opening and closing sendmail for each email address in the array

any ideas ??
foreach (@mail_to) { open(SENDMAIL, "|$sendmail") or die "Cannot open $sendmail: $!"; print SENDMAIL "To: $_ \n"; print SENDMAIL "From: csorensen\@uptimeresources.net \n"; print SENDMAIL "Subject: South African tourism survey \n"; print SENDMAIL "Content-type: text/plain \n\n"; print SENDMAIL $content; close(SENDMAIL); }

I moved the FIFO outside the loop and kept the print statements inside.. it created one MONSTER email for everyone and sent it to the first address.. oops !

Comment on eof without closing the pipe
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Re: eof without closing the pipe
by Shendal (Hermit) on Jun 30, 2000 at 00:56 UTC
    How about this:
    open(SENDMAIL"|$sendmail") or die "Cannot open $sendmail: $!"; print SENDMAIL "To: " . join ",",@mail_to . "\n"; print SENDMAIL "From: csorensen\@uptimeresources.net \n"; print SENDMAIL "Subject: South African tourism survey \n"; print SENDMAIL "Content-type: text/plain \n\n"; print SENDMAIL $content; close(SENDMAIL);
      Would this join create an enormously fat To: line that would get sent to everybody in it or does it do something more subtle?

      -PipTigger

      p.s. Initiate Nail Removal Immediately!
        It would create an enormously fat To: line. I guess you could use bcc to hide that, but the original question didn't want to use bcc. Another choice is using bulkmail, which has already been suggested by someone else.
Re: eof without closing the pipe
by chromatic (Archbishop) on Jun 30, 2000 at 01:36 UTC
    The author of Mail::Bulkmail claims it can process at least 884 messages per minute. If you promise your intentions are noble, have a look at that module.
      thanks .. people have mentioned that module to me before. I was hoping that someone knew a command that sent "eof" or something similiar to sendmail.
RE: eof without closing the pipe
by cleen (Pilgrim) on Jun 30, 2000 at 07:30 UTC
    I know Im going to get flamed for this becuase Im not using a module, but its quick and it works, plus that its quicker becuase it doesnt even open up a pipe..It uses a simple socket connection to a sendmail server (just one)
    #!/usr/bin/perl use strict; use Socket; my @users=('email1@server.com', 'email2@server.com', 'email3@server.co +m'); my $mailhost="localhost"; my $myemail="mark\@cidera.com"; # Your email address # this is just the subject and body of the message # you can get this information from anywhere I just # put it in here for the sake of example my $subject= "hi"; my $data = "hi hi hi hi there"; my $userz; socket(MAIL,PF_INET,SOCK_STREAM,getprotobyname('tcp')); connect(MAIL,sockaddr_in(25,inet_aton($mailhost))); select(MAIL); $|=1; select('stdout'); print MAIL "HELO blah.com\n"; foreach $userz (<@users>) { print MAIL "MAIL FROM: $myemail\n"; print MAIL "RCPT TO: $userz\n"; print MAIL "DATA\n"; print MAIL "Subject: $subject\n"; print MAIL "$data\n"; print MAIL ".\n"; } print MAIL "quit\n"; close(MAIL);
    This works becuase it doesnt quit the sendmail connection till after all the emails have been sent to each person in your @users array seperatly.

    I know this isnt EXACTLY what you were looking for, but its just another way to do this.
      I will not flame you. Looks like a nice way to do the job. There is not many who speak "natively" with sendmail nowdays ;)

      /brother t0mas
      It's nice to see someone else who uses socket (not socket.pm) and knows a protocol or two.
      now, maybe i am mistaken... however, opening up a socket connection, no matter how simple, should be MARKEDLY slower than opening up a pipe, no matter what the situation. If you are opening up a socket to a host you have to deal with:
      • TCP/IP overhead
      • Network Transport Layer Overhead
      • Communicational Latency
      • The fact that you are communicating via external means, instead of the bus!
      however, if you are opening up a pipe, to a process on the local machine then the situation is:
      • there is NO TCP/IP overhead
      • there is NO network layer overhead
      • the communicational latency is the velocity at which the receiving process can aquire STDIN
      • and you are communicating through memory and the bus, which have a MUCH greater bandwith and throughput than most any network connection!
      if speed is your constraint, and you are attempting to maximize the throughput (here being messages per minute) I can not conceive of a way faster than communicating directly with sendmail through a pipe.

      UPDATE: thanks to lhoward i have now learned that in modern operating systems, much to my suprise, the TCP subsystem has been optimized WAY better than I ever thought it would be, so, my entire coment above, should be disreguarded and i should be flogged for not having benchmarked in the first place :) keep the learning coming...

        Opening a socket is typically as fast or faster than opening a pipe.

        Pipe issues:

        • Have the overhead of starting a separate process. (you may or may not have this overhead when doing a TCP socket connection depending on if the server is forking or threading)
        socket/TCP port issues:
        • Most OSes have highly optimized TCP/IP stacks, generally much more optmized than the OSes core pipe processing functions. For today's applications network performance is typically much more important than pipe performance.
        • localhost TCP/IP connections (where client and server are on the same host) do not go out "on the wire", they are typically highly optimized with direct memory-to-memory exchange of the data. Localhost network connections have practially 0 network overhead.

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