System Overview

"What kind of server is this? How long has it been up? What version is the kernel?"

These questions come up constantly. Let's learn the quick answers.

hostname - What's This Machine Called?

Terminal

$hostname

webserver-01

$hostname -f

webserver-01.example.com

-f gives the fully qualified domain name (FQDN).

uname - System Information

Terminal

$uname

Linux

$uname -a

Linux webserver-01 5.15.0-91-generic #101-Ubuntu SMP x86_64 GNU/Linux

-a shows everything: kernel name, hostname, kernel version, architecture.

Individual Flags

Flag	Shows
`-s`	Kernel name (Linux)
`-n`	Hostname
`-r`	Kernel release
`-v`	Kernel version
`-m`	Machine hardware (x86_64)
`-o`	Operating system

Terminal

$uname -r

5.15.0-91-generic

$uname -m

x86_64

uptime - How Long Running?

Terminal

$uptime

10:30:45 up 45 days, 3:22, 2 users, load average: 0.15, 0.10, 0.09

Shows:

Current time
Uptime
Users logged in
Load averages (1, 5, 15 minutes)

Load Average

Load average shows CPU demand. Compare to your core count:

1.0 on 1 core = 100% utilized
4.0 on 4 cores = 100% utilized Higher than core count = overloaded

Distribution Information

/etc/os-release

Terminal

$cat /etc/os-release

NAME="Ubuntu" VERSION="22.04.3 LTS (Jammy Jellyfish)" ID=ubuntu VERSION_ID="22.04" PRETTY_NAME="Ubuntu 22.04.3 LTS"

lsb_release

Terminal

$lsb_release -a

Distributor ID: Ubuntu Description: Ubuntu 22.04.3 LTS Release: 22.04 Codename: jammy

Date and Time

Terminal

$date

Tue Jan 14 10:30:45 UTC 2025

$date +%Y-%m-%d

2025-01-14

$date +%s

1736850645

%s gives Unix timestamp (seconds since 1970).

Timezone

Terminal

$timedatectl

Local time: Tue 2025-01-14 10:30:45 UTC Universal time: Tue 2025-01-14 10:30:45 UTC Time zone: UTC (UTC, +0000)

Quick System Check Script

echo "=== System Overview ==="
echo "Hostname: $(hostname)"
echo "OS: $(cat /etc/os-release | grep PRETTY_NAME | cut -d'=' -f2)"
echo "Kernel: $(uname -r)"
echo "Uptime: $(uptime -p)"
echo "Users: $(who | wc -l)"
echo "Load: $(cat /proc/loadavg | cut -d' ' -f1-3)"

Knowledge Check

What does a load average of 4.0 on a 2-core system indicate?

Quick Reference

Command	Shows
`hostname`	Machine name
`uname -a`	All system info
`uname -r`	Kernel version
`uptime`	Uptime and load
`cat /etc/os-release`	Distribution info
`date`	Current date/time
`timedatectl`	Time settings

Key Takeaways

hostname tells you what machine you're on
uname -a gives kernel and architecture
uptime shows how long system's been running
/etc/os-release identifies the distribution
Load average should stay below your core count

Next: checking disk usage.

System Overview

"What kind of server is this? How long has it been up? What version is the kernel?"

These questions come up constantly. Let's learn the quick answers.

hostname - What's This Machine Called?

Terminal

$hostname

webserver-01

$hostname -f

webserver-01.example.com

-f gives the fully qualified domain name (FQDN).

uname - System Information

Terminal

$uname

Linux

$uname -a

Linux webserver-01 5.15.0-91-generic #101-Ubuntu SMP x86_64 GNU/Linux

-a shows everything: kernel name, hostname, kernel version, architecture.

Individual Flags

Flag	Shows
`-s`	Kernel name (Linux)
`-n`	Hostname
`-r`	Kernel release
`-v`	Kernel version
`-m`	Machine hardware (x86_64)
`-o`	Operating system

Terminal

$uname -r

5.15.0-91-generic

$uname -m

x86_64

uptime - How Long Running?

Terminal

$uptime

10:30:45 up 45 days, 3:22, 2 users, load average: 0.15, 0.10, 0.09

Shows:

Current time
Uptime
Users logged in
Load averages (1, 5, 15 minutes)

Load Average

Load average shows CPU demand. Compare to your core count:

1.0 on 1 core = 100% utilized
4.0 on 4 cores = 100% utilized Higher than core count = overloaded

Distribution Information

/etc/os-release

Terminal

$cat /etc/os-release

NAME="Ubuntu" VERSION="22.04.3 LTS (Jammy Jellyfish)" ID=ubuntu VERSION_ID="22.04" PRETTY_NAME="Ubuntu 22.04.3 LTS"

lsb_release

Terminal

$lsb_release -a

Distributor ID: Ubuntu Description: Ubuntu 22.04.3 LTS Release: 22.04 Codename: jammy

Date and Time

Terminal

$date

Tue Jan 14 10:30:45 UTC 2025

$date +%Y-%m-%d

2025-01-14

$date +%s

1736850645

%s gives Unix timestamp (seconds since 1970).

Timezone

Terminal

$timedatectl

Local time: Tue 2025-01-14 10:30:45 UTC Universal time: Tue 2025-01-14 10:30:45 UTC Time zone: UTC (UTC, +0000)

Quick System Check Script

echo "=== System Overview ==="
echo "Hostname: $(hostname)"
echo "OS: $(cat /etc/os-release | grep PRETTY_NAME | cut -d'=' -f2)"
echo "Kernel: $(uname -r)"
echo "Uptime: $(uptime -p)"
echo "Users: $(who | wc -l)"
echo "Load: $(cat /proc/loadavg | cut -d' ' -f1-3)"

Knowledge Check

What does a load average of 4.0 on a 2-core system indicate?

Quick Reference

Command	Shows
`hostname`	Machine name
`uname -a`	All system info
`uname -r`	Kernel version
`uptime`	Uptime and load
`cat /etc/os-release`	Distribution info
`date`	Current date/time
`timedatectl`	Time settings

Key Takeaways

hostname tells you what machine you're on
uname -a gives kernel and architecture
uptime shows how long system's been running
/etc/os-release identifies the distribution
Load average should stay below your core count

Next: checking disk usage.