Different outputs for `w`, `who`, `whoami` and `id`












8















In command line platforms online, like for instance the one on Codecademy, when I run



for cmd in w who whoami id
do
echo $cmd
$cmd
echo =========================
echo " "
done


I get



w                              
00:52:54 up 8 days, 14:10,  0 users,  load average: 3.78, 2.98, 2.69      
USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT       
=========================                            

who
=========================                                                 

whoami                          
ccuser                          
=========================                              
  
id
uid=1000(ccuser) gid=1000(ccuser) groups=1000(ccuser)     
=========================                   


Note that only whoami and id output something. When I run the same thing on my computer, I see similar results for all commands.



Why doesn't Codecademy display the user for w and who? What's different about these commands?










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    8















    In command line platforms online, like for instance the one on Codecademy, when I run



    for cmd in w who whoami id
    do
    echo $cmd
    $cmd
    echo =========================
    echo " "
    done


    I get



    w                              
    00:52:54 up 8 days, 14:10,  0 users,  load average: 3.78, 2.98, 2.69      
    USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT       
    =========================                            

    who
    =========================                                                 

    whoami                          
    ccuser                          
    =========================                              
      
    id
    uid=1000(ccuser) gid=1000(ccuser) groups=1000(ccuser)     
    =========================                   


    Note that only whoami and id output something. When I run the same thing on my computer, I see similar results for all commands.



    Why doesn't Codecademy display the user for w and who? What's different about these commands?










    share|improve this question









    New contributor




    whoami is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.























      8












      8








      8


      2






      In command line platforms online, like for instance the one on Codecademy, when I run



      for cmd in w who whoami id
      do
      echo $cmd
      $cmd
      echo =========================
      echo " "
      done


      I get



      w                              
      00:52:54 up 8 days, 14:10,  0 users,  load average: 3.78, 2.98, 2.69      
      USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT       
      =========================                            

      who
      =========================                                                 

      whoami                          
      ccuser                          
      =========================                              
        
      id
      uid=1000(ccuser) gid=1000(ccuser) groups=1000(ccuser)     
      =========================                   


      Note that only whoami and id output something. When I run the same thing on my computer, I see similar results for all commands.



      Why doesn't Codecademy display the user for w and who? What's different about these commands?










      share|improve this question









      New contributor




      whoami is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.












      In command line platforms online, like for instance the one on Codecademy, when I run



      for cmd in w who whoami id
      do
      echo $cmd
      $cmd
      echo =========================
      echo " "
      done


      I get



      w                              
      00:52:54 up 8 days, 14:10,  0 users,  load average: 3.78, 2.98, 2.69      
      USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT       
      =========================                            

      who
      =========================                                                 

      whoami                          
      ccuser                          
      =========================                              
        
      id
      uid=1000(ccuser) gid=1000(ccuser) groups=1000(ccuser)     
      =========================                   


      Note that only whoami and id output something. When I run the same thing on my computer, I see similar results for all commands.



      Why doesn't Codecademy display the user for w and who? What's different about these commands?







      users who w whoami






      share|improve this question









      New contributor




      whoami is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      share|improve this question









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      whoami is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.









      share|improve this question




      share|improve this question








      edited Mar 17 at 10:50







      whoami













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      asked Mar 17 at 1:04









      whoamiwhoami

      433




      433




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          1 Answer
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          12
















          • id reports


            • the current credentials of its own process; or

            • the credentials of a named user, as read out of the system account database.




          • whoami reports the current credentials of its own process.


          • who and w report the active login sessions table from the login database.


          BSD doco notes that whoami does a subset of the job of id, and that id renders it obsolete.



          A system does not have to have an active login sessions table. On Linux operating systems and on the BSDs, if the table has not been created at bootstrap, or has been deleted since, the system will operate without one. Logging in and out does not implicitly create it on Linux operating systems, moreover.



          Furthermore, the table need not be readable by unprivileged users and neither the who nor the w command will report this as an error.



          Further reading




          • Jonathan de Boyne Pollard (2018). The Unix login database. Frequently Given Answers.

          • Jonathan de Boyne Pollard (2018). "login-update-utmpx". User Commands. nosh toolset.

          • Lennart Poettering et al. (2018). systemd-update-utmp.service. systemd manual pages. Freedesktop.org.

          • Is it necessary for a login-shell to create utmp entry?

          • https://unix.stackexchange.com/a/409036/5132






          share|improve this answer

























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            12
















            • id reports


              • the current credentials of its own process; or

              • the credentials of a named user, as read out of the system account database.




            • whoami reports the current credentials of its own process.


            • who and w report the active login sessions table from the login database.


            BSD doco notes that whoami does a subset of the job of id, and that id renders it obsolete.



            A system does not have to have an active login sessions table. On Linux operating systems and on the BSDs, if the table has not been created at bootstrap, or has been deleted since, the system will operate without one. Logging in and out does not implicitly create it on Linux operating systems, moreover.



            Furthermore, the table need not be readable by unprivileged users and neither the who nor the w command will report this as an error.



            Further reading




            • Jonathan de Boyne Pollard (2018). The Unix login database. Frequently Given Answers.

            • Jonathan de Boyne Pollard (2018). "login-update-utmpx". User Commands. nosh toolset.

            • Lennart Poettering et al. (2018). systemd-update-utmp.service. systemd manual pages. Freedesktop.org.

            • Is it necessary for a login-shell to create utmp entry?

            • https://unix.stackexchange.com/a/409036/5132






            share|improve this answer






























              12
















              • id reports


                • the current credentials of its own process; or

                • the credentials of a named user, as read out of the system account database.




              • whoami reports the current credentials of its own process.


              • who and w report the active login sessions table from the login database.


              BSD doco notes that whoami does a subset of the job of id, and that id renders it obsolete.



              A system does not have to have an active login sessions table. On Linux operating systems and on the BSDs, if the table has not been created at bootstrap, or has been deleted since, the system will operate without one. Logging in and out does not implicitly create it on Linux operating systems, moreover.



              Furthermore, the table need not be readable by unprivileged users and neither the who nor the w command will report this as an error.



              Further reading




              • Jonathan de Boyne Pollard (2018). The Unix login database. Frequently Given Answers.

              • Jonathan de Boyne Pollard (2018). "login-update-utmpx". User Commands. nosh toolset.

              • Lennart Poettering et al. (2018). systemd-update-utmp.service. systemd manual pages. Freedesktop.org.

              • Is it necessary for a login-shell to create utmp entry?

              • https://unix.stackexchange.com/a/409036/5132






              share|improve this answer




























                12












                12








                12









                • id reports


                  • the current credentials of its own process; or

                  • the credentials of a named user, as read out of the system account database.




                • whoami reports the current credentials of its own process.


                • who and w report the active login sessions table from the login database.


                BSD doco notes that whoami does a subset of the job of id, and that id renders it obsolete.



                A system does not have to have an active login sessions table. On Linux operating systems and on the BSDs, if the table has not been created at bootstrap, or has been deleted since, the system will operate without one. Logging in and out does not implicitly create it on Linux operating systems, moreover.



                Furthermore, the table need not be readable by unprivileged users and neither the who nor the w command will report this as an error.



                Further reading




                • Jonathan de Boyne Pollard (2018). The Unix login database. Frequently Given Answers.

                • Jonathan de Boyne Pollard (2018). "login-update-utmpx". User Commands. nosh toolset.

                • Lennart Poettering et al. (2018). systemd-update-utmp.service. systemd manual pages. Freedesktop.org.

                • Is it necessary for a login-shell to create utmp entry?

                • https://unix.stackexchange.com/a/409036/5132






                share|improve this answer

















                • id reports


                  • the current credentials of its own process; or

                  • the credentials of a named user, as read out of the system account database.




                • whoami reports the current credentials of its own process.


                • who and w report the active login sessions table from the login database.


                BSD doco notes that whoami does a subset of the job of id, and that id renders it obsolete.



                A system does not have to have an active login sessions table. On Linux operating systems and on the BSDs, if the table has not been created at bootstrap, or has been deleted since, the system will operate without one. Logging in and out does not implicitly create it on Linux operating systems, moreover.



                Furthermore, the table need not be readable by unprivileged users and neither the who nor the w command will report this as an error.



                Further reading




                • Jonathan de Boyne Pollard (2018). The Unix login database. Frequently Given Answers.

                • Jonathan de Boyne Pollard (2018). "login-update-utmpx". User Commands. nosh toolset.

                • Lennart Poettering et al. (2018). systemd-update-utmp.service. systemd manual pages. Freedesktop.org.

                • Is it necessary for a login-shell to create utmp entry?

                • https://unix.stackexchange.com/a/409036/5132







                share|improve this answer














                share|improve this answer



                share|improve this answer








                edited Mar 17 at 2:16

























                answered Mar 17 at 1:43









                JdeBPJdeBP

                37.4k477179




                37.4k477179






















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