In this tutorial, I will explain 15 useful commands which it’s the useful and frequently used Linux or Unix commands for Linux System Administrators that are used in most of their times during their entire life.
This is not all commands but it’s a compact list of commands to refer when needed. Let’s start to explain this commands and try it as I will provide a screenshot for each command.
1. The below command display how long this system is running as how many users are currently logged in.
uptime
2. The command “W“, display the current logged in users and also the process for each user, login name, tty name, remote host, login time, idle time, JCPU, PCPU.
3. The below command displays only the current username without any other parameters.
users
4. The command “WHO” gives you the username, date, time and the current host information.
5. The command “ls” display all the files so you can know what every directory contains.
6. The command “crontab” list all the scheduled jobs for the current logged in user, but you have to provide with “-l”, the below screenshot display that there are no scheduled jobs for the user.
7. The command “pwd” gives you the current directory.
8. “SSH” this command is used to login to a remote service/server, but you need to provide the user with it check the below screenshot.
9. The command “gzip” to create a compressed file.
10. The command “shutdown -h” is used to turn the machine off, you can schedule it by adding “+” following by the required time.
11. The command “free” is used to show you the free and used swap memory that you can use in your system.
12. The command “top” is used to show you all the current top process on your system.
13. The command “df” show you the file system disk space usage.
14. The command “ifconfig -a” will view all your network card interface details.
15. The command “ping” to ping any host or web service/server, use it like the below screenshot.
