Monitoring System Usage

Many shell commands exist to help you monitor the system. The last command shows you which users have logged in most recently or when a specified user last logged in to your system.

The id command allows you to determine which groups a particular user has access to or to determine the short name for a user, given their UID.

Mac OS X systems maintain many log files. Viewing log files on your system or on another system using ssh can help you troubleshoot any number of problems. The command

tail -n 10 /Library/Logs/Software\ Update.log

displays the 10 most recently installed software updates. The command

tail -f /var/log/system.log

displays the current contents of the system log, then continues to print new lines as they are added to the file.