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I have graphical machine of rhel7 , when i run who command , the output of 4th column is ':0' , what does that mean? When my other machine take access of this graphical machine , the output of who commands 4th column is ip address of the machine that took the graphical machine's ssh , please explain why so.

marked as duplicate by Mat, X Tian, Barmar, dhag, muru Oct 15 '15 at 16:29

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  • 2
    man who and who -H.. You are like walking through all the columns. – Arthur2e5 Oct 15 '15 at 13:35
  • 2
    shall we call Doctor Who ? – Archemar Oct 15 '15 at 13:40
  • 1
    @Archemar Well, who only outputs 4 cols and I think this question is the last one. – Arthur2e5 Oct 15 '15 at 13:41
  • @Arthur2e5 - that answer is for the 2nd column - I'll post another answer here for the 4th column and hopefully get some points :-) – garethTheRed Oct 15 '15 at 13:56
  • @garethTheRed wait, .. ah, you are right, 2nd col may contain :0 as well. – Arthur2e5 Oct 15 '15 at 14:21

The fourth column (comment column) is actually the column, as you have said, that displays the IP address of the machine through which the user has logged in. Meaning of ':0' is that the IP address of the machine is localhost and nothing else. Which means the user is logged in from the same machine where the OS is installed and not any other machine in the network

Edit: I must say that this site does not work like the way you used it. You should have made thorough research attempts and then you should have posted this question. A simple google search gave me this http://linoxide.com/linux-command/linux-who-command/

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