Where are the POSIX message functions (msgsnd, msgrcv, etc) man pages in Mac?

You can download them from http://manpages.ubuntu.com.

For example, to download man page msgsnd (3):

  1. Search for msgsnd in the Google Custom Search field on the right hand side:

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  2. Click on the newest man page in section 3:

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  3. Download the linked .gz man page:

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  4. Copy it to the man directory:

    • If you want to keep system and additional man pages apart, copy it to /usr/local/share/man/man3/:

      sudo mkdir -p /usr/local/share/man/man3/
      sudo cp ~/Downloads/msgsnd.3posix.gz /usr/local/share/man/man3/
      

      and add:

      export MANPATH="/usr/local/share/man:$MANPATH"
      

      to /etc/profile, if you wish the new man page to be available system-wide, or ~/.bash_profile, to be available to your user only (see man man, that is, man's man page, for more information on MANPATH.)

      Open a new Terminal window or tab for changes to take effect.

    • Otherwise, copy the man page to /usr/share/man/man3:

      sudo cp /Users/jaume/Downloads/msgsnd.3posix.gz /usr/share/man/man3/
      
  5. Enjoy:

    man 3 msgsnd
    
    MSGSND(P)                POSIX Programmer's Manual                MSGSND(P)
    
    NAME
           msgsnd - XSI message send operation
    (...)