logname

Wat het doet

Zo schrijf je het

logname [OPTION]

Meest gebruikt

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$ als gewone gebruiker# als root (of met sudo)

1. 1Show the login name

   $logname
   student

   The user who logged in.

2. 2After switching to root

   $sudo -i
   #whoami; logname
   root
   student

   logname still shows the real person.

3. 3Use the real user in a root script

   #echo "$(date) $(logname) changed the firewall" >> /var/log/admin-changes.log

   Better audit text than "root".

4. 4Compare with SUDO_USER

   $sudo sh -c 'echo $SUDO_USER; logname'
   student
   student

   SUDO_USER is set only by sudo; logname also works after su.

5. 5Without a terminal

   $ssh server2 logname
   logname: no login name

   A remote command without a terminal has no login record.

6. 6In cron

   $crontab -l | grep logname

   Cron jobs have no login name; use id -un there.

7. 7Give a file back to the real user

   #chown "$(logname)": /tmp/report.txt

   After a root script, the user can open the file.

8. 8Check the login records

   $who am i
   student  pts/0        2026-10-25 09:02 (192.168.122.1)

   logname reads the same data.

9. 9Script that needs a person

   $logname >/dev/null 2>&1 || echo "no interactive login"

   Exit code 1 when there is no login name.

10. 10Show the home folder of the real user

    #getent passwd "$(logname)" | cut -d: -f6
    /home/student

    Useful in an install script run with sudo.

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