whoami, hostname, uname, ps & df

Know your system

Lesson 17 of 20 · 9 min · Module 5: Permissions and the system

Before you change a server, confirm where you are and how it is doing. A few short commands answer the basic questions.

Free. No installation: you write and run the code in your browser, and it is checked automatically.

By the end, you’ll be able to…

Confirm user and machine
Inspect processes and disk space
Read environment variables

The idea

whoami shows your user, hostname the computer’s name, and uname -a the system and kernel. ps aux lists running programs. df -h shows free disk space in readable units. echo $HOME prints an environment variable.

whoami
hostname
uname -a
df -h

01Confirm before you act

On a real job you may have several terminal windows connected to different servers. whoami and hostname take a second and prevent running a command on the wrong machine.

02Read the disk report

df -h lists each filesystem with its size, used and available space, and Use%. Above about 90 percent, programs may start failing to write files.

df -h

Output

Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1        40G   36G  4.0G  91% /

03Variables carry settings

$HOME, $USER, and $PATH are environment variables. echo $PATH shows where the shell looks for commands. env lists all of them.

Your turn

Print your user name and the computer’s name. Then save the disk space report from df -h into disk.txt in your home folder.

What the checks look for

Shows the user learner
Shows the host name codetemper
Saves the df -h report to disk.txt

Try it in the editor →

Take this with you

A quick look at user, host, disk, and processes is the first step of any server check.

Go a little further

Run ps aux and find the processes for the web server nginx and the database postgres.