in /etc/postfix/ what does ^M mean?

Discussion in 'Technical' started by adamjedgar, Nov 14, 2019.

  1. adamjedgar

    adamjedgar Member

    I have an ISPConfig installation that was done using the automated script.

    I have been going through the perfect server setup just checking on things to see differences between the auto installer and the tutorial

    in my /etc/postfix/ i note the following two lines
    ^M -o smtpd_client_restrictions=permit_sasl_authenticated,reject
    ^M -o smtpd_client_restrictions=permit_sasl_authenticated,reject
    what does the ^M mean?
  2. Taleman

    Taleman Well-Known Member HowtoForge Supporter

    How are you looking at that file? ^M looks like a control character, Control-M or carriage return.
    If you are not sure what exactly is in that file, try
    od -c /etc/postfix/ | less
    to see character by character what exactly is in that file. If there are extra control characters they should be removed. If, on the other hand, those ^M appear where line breaks should be, has that file been copied between different systems with different ways to code line breaks?
  3. Steini86

    Steini86 Active Member

  4. adamjedgar

    adamjedgar Member

    BTW, the two lines are the same/repeated because they come from different parts of the file (so there are at least two locations where this same line exists)

    I am viewing this in putty using the nano editor.

    also, this is a default ispconfig install using the automated anything put there came from the script...i didnt do a perfect server setup first.

    is it possible that this character in the postfix file causes a dialogue box to popup before that function is executed?
  5. Taleman

    Taleman Well-Known Member HowtoForge Supporter

    What dialogue box? Where does it pop up? Which function is executed?
    Since you wrote putty and nano editor, I guess you are using Windows workstation? Windows and Unix/Linux use different line breaks, so that may be the source of confusion. But I have not seen the ^M problem you experience. Try to edit the file, remove the M and see what happens. If it is Control-M then although it is shown on screen as ^ and M it is only one character, so one backspace should remove both. Or use the od -c like I wrote previously.
    Then check settings in Putty, is it configured to do something to line breaks?
  6. adamjedgar

    adamjedgar Member

    Ok I will try that...but it can't be a Windows thing...I have four vps servers
    2 x virtualmin
    1 x ispconfig
    1 x centos-web panel

    And have also had vestacp on a fifth vps.

    None of the others have ever had these entries for mail server configuration...this is the only/first time I have seen this...So I thought perhaps the ispconfig automated installer script had done it intentionally for a reason? I am a little surprised the developer hasn't simply jumped in here and said "my code doesnt/shouldn't do that! " Then someone might actually check the script to ensure that their is nothing wrong with it, whereby this could happen during install. That would enable me to narrow down how this code came to be there.

    I know 100%, I did not manually type that code in, however perhaps I have copy and pasted code via Windows in a web browser that has caused this? (I usually only use howtoforge tutorials for ispconfig system...but on virtualmin system, because of their crap documentation, i often am forced to go for third party solutions to problems and maybe I have inadvertently done this by mistake thinking I was on other system (I often have multiple server open at same time on different screens doing stuff)? I don't recall having done this...but just trying to cover all possible bases.
  7. till

    till Super Moderator Staff Member ISPConfig Developer

    You did not even say which script you used. There is not 'the automated script' as there are several scripts available which are not developed by ISPConfig developers and I doubt that their authors read the forum on a regular basis.

    When using putty with a Linux commandline editor like nano, this should not happen. But if you edit files with a scp client, then it's possible.
  8. adamjedgar

    adamjedgar Member

    Last edited: Nov 16, 2019
  9. till

    till Super Moderator Staff Member ISPConfig Developer

    1) You did not mention in this thread which Linux Distribution and version you are using.
    2) The script you used is not from ISPConfig and I doubt that its developer will read all posts here.
    3) There are several installer scripts available as I mentioned already: ISPconfig autoinstaller from Servisys, ISPConfig Kickstarter and the new official ISPConfig Installer and I know some other companies have developed their own autoinstall scripts, so there exist even more than the 3 I mentioned.

    It makes a difference. But I see to fail now why I shall help you again in future after reading your answer, or shall I spell it out more clearly....
  10. adamjedgar

    adamjedgar Member

    So Till you are saying that the Postfix configuration file entries for Debian, Centos, and Ubuntu are all different? So when I goto /etc/postfix/, I should expect to find different entries for each of the above mentioned Operating Systems?

    You dont need to be defensive of your product,I am not attacking your product or you! This is not an "anti-donald trump media campaign"... its genuine effort on my part to try to understand under what circumstances that ^M could be in such a file.

    People who use automated installers dont necessarily check these things...because the script does most everything for a working setup. so it could be that others have the exact same entries in their postfix configuration and dont even know it?

    I make the assumption that when i am using a tutorial vetted and obviously approved by you, then when i come across something unusual on my install, you/your forums would be the resource that i approach for guidance. So here i am.​

    All i am asking is
    1. is this an expected entry from one of the vetted installer scripts and if not,
    2. can i safely remove it

    Do well really need to go through all of the above ear-bashing to get those two answers?
  11. Taleman

    Taleman Well-Known Member HowtoForge Supporter

    They may quite well be. There are countless operating systems, so it is just futile to guess what should be in a configuration file without knowing the OS and version.
    If your claim is that Postfix configuration files are identical across all operating systems and versions, you can easily prove this.
    I do not understand this amount of fuss over ^M in a file. I have asked you to use od -c or some other dump of file contents to see what actually is in that file, so there would be some amount of actual data to base this discussion on. This is now 10 entries in thread, and still it is not known what the file has at that spot or if the editor used just displays ^M for some reason.
  12. till

    till Super Moderator Staff Member ISPConfig Developer

    The files are different for each OS but what's even more important is that an installer script might use different code based on the OS and that's why it is important to know which OS and which installer you use.



    Your question was ansered with the first two responses after which you continued to raise new questions and complain that the author of a third party script did not read your post.

Share This Page