Linux System Information Commands: Essential Tools for System Administration
Contents
Introduction
Explore essential Linux system information commands, including uname, lsb_release, and more. Learn how to retrieve valuable system data and optimize your system’s performance.
Linux provides a variety of commands to gather system information.
Here are some commonly used commands to retrieve system information:
Remember that many of these commands may require super (root) privileges to access certain system information.
Additionally, the availability and behavior of these commands may vary slightly between different Linux distributions.
hostname:
Displays the system’s hostname.
hostname: code example
To retrieve the hostname of a Linux system using a code example, you can use various programming languages.
Example in Python:
import socket
def get_hostname():
hostname = socket.gethostname()
return hostname
if __name__ == "__main__":
hostname = get_hostname()
print("Hostname:", hostname)
- This Python script uses the socket module to retrieve the system’s hostname and then prints it to the console. You can save this script to a .py file, execute
- it using Python, and it will display the hostname of the Linux system.
Here’s how you can run the script in your terminal:
- Create a file, e.g., get_hostname.py, and paste the Python code into it.
- Open your terminal and navigate to the directory where you saved the script.
Run the script using the following command:
python get_hostname.py
It will display the hostname of your Linux system.
uname:
- Shows system information like the kernel name, network node hostname, kernel release, kernel version, machine hardware name, and processor type.
- You can use the uname command in a Linux terminal to display system information.
Here’s an example of how to use the uname command:
- Open your terminal and simply type the following command:
uname -a
- This command will provide a detailed output with information such as the kernel name, network node hostname, kernel release, kernel version, machine hardware name, and processor type.
For example, the output might look like this:
Linux mycomputer 5.4.0-91-generic #102-Ubuntu
SMP Fri Aug 13 16:18:06
UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
- This output includes information about the kernel version, hostname, architecture, and more.
- The specific details may vary depending on your system and Linux distribution.
lsb_release Linux command:
- Provides information about the Linux distribution.
Here’s an example of how to use it:
Open your terminal and run the following command:
lsb_release -a
- This command will provide detailed information about your Linux distribution, including the distributor ID, description, release number, and codename.
The output might look something like this:
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04.3 LTS
Release: 20.04
Codename: focal
- The specific details in the output may vary depending on your Linux distribution and version.
- This information is useful for identifying your distribution and its version.
cat /etc/os-release Linux command:
Another way to display information about the Linux distribution.
cat /etc/os-release:
- You can use the cat command to display the contents of the /etc/os-release file
- It typically contains information about the Linux distribution.
Here’s an example:
Open your terminal and run the following command:
cat /etc/os-release
This command will display the content of the /etc/os-release file, which may look something like this:
PRETTY_NAME=”Ubuntu 20.04.3 LTS”
NAME=”Ubuntu”
VERSION=”20.04.3 LTS (Focal Fossa)”
ID=ubuntu
ID_LIKE=debian
HOME_URL=”https://www.ubuntu.com/”
SUPPORT_URL=”https://help.ubuntu.com/”
BUG_REPORT_URL=”https://bugs.launchpad.net/ubuntu/”
PRIVACY_POLICY_URL=”https://www.ubuntu.com/legal
/terms-and-policies/privacy-policy”
The specific details in the output will correspond to your Linux distribution and version.
This file is a common way to obtain information about your Linux distribution programmatically.
cat /etc/issue Linux command:
Displays the system’s issue file, which may contain distribution-specific information.
cat /etc/issue:example
- The /etc/issue file typically contains a message or banner that is displayed when someone logs into the system.
- It may contain distribution-specific information or a custom message set by the system administrator.
- To display the content of this file, you can use the cat command.
Here’s an example:
Open your terminal and run the following command:
cat /etc/issue
The output will depend on what is in the /etc/issue file on your system.
Here’s an example of what you might see:
Welcome to My Linux System
This is a customized message or banner.
You can add important information or instructions here.
The specific content of the file can vary depending on the system’s configuration and the preferences of the system administrator.
Top Linux command:
Real-time system monitoring tool showing system information and process statistics.
- The top command is used to display real-time system statistics, including information about running processes, system load, memory usage, and more.
top:example
Here’s an example of how to use the top command:
Open your terminal.
Simply type top and press Enter.
top
The top command will start displaying a real-time, updating view of system information and processes.
Here’s a brief explanation of some of the columns you might see in the top display:
PID: Process ID.
: The who started the process.
PR: Priority of the process.
NI: The nice value of the process.
VIRT: Virtual memory used by the process.
RES: Resident (non-swapped) physical memory used by the process.
SHR: Shared memory used by the process.
S: The status of the process (e.g., R for running, S for sleeping).
%CPU: Percentage of CPU usage by the process.
%MEM: Percentage of memory usage by the process.
TIME+: Total CPU time used by the process.
COMMAND: The command that started the process.
How to Exit top command?
To exit top, you can press the q key.
You can also sort the processes by different columns by pressing the corresponding keys (e.g., press P to sort by CPU usage, M to sort by memory usage).
top:
Here’s an example of using the top command in a Linux terminal:
Open your terminal.
Simply type top and press Enter.
top
- The top command will start displaying real-time system statistics and a list of running processes.
- It will continuously update the information on your terminal screen.
Here’s an example of what the top display might look like:
top – 10:00:00 up 1 day, 1:30, 1 , load average: 0.00, 0.02, 0.05
Tasks: 236 total, 1 running, 235 sleeping, 0 stopped, 0 zombie
%Cpu(s): 3.2 us, 1.0 sy, 0.0 ni, 95.6 id, 0.1 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem : 2048348 total, 1676684 free, 195496 used, 1731680 buff/cache
KiB Swap: 2097148 total, 2097024 free, 12384 used. 1641580 avail Mem
PID PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
997 root 20 0 394488 64516 55540 S 6.6 3.2 2:35.51 Xorg
2454 20 0 1055056 151100 38108 S 3.6 7.4 3:10.35 gnome-shell
1140 20 0 2257800 133676 50448 S 2.6 6.5 6:09.82 gnome-software
1879 20 0 1965588 110508 27180 S 2.0 5.4 3:31.18 chrome
698 20 0 584440 74864 27576 S 1.3 3.7 0:47.69 gnome-terminal
591 20 0 1725588 98372 48428 S 1.0 4.8 1:43.42 gnome-shell
- The top command provides information about system load, the number of tasks, CPU usage, memory usage, and a list of running processes.
- You can navigate and interact with the top interface to sort processes, send signals to processes, and more.
- To exit top, press the q key.
Htop Linux command:
htop is an interactive process viewer that provides a more detailed and -friendly representation of system information compared to top.
htop:
Here’s an example of how to use the htop command:
Open your terminal.
Simply type htop and press Enter.
htop
- htop will start and display a real-time, updating view of system information and running processes.
- It provides a colorful and interactive interface with a lot of useful information.
Here’s an example of what the htop display might look like:
1 [|||||||||||||||||||||||||||||||||||100.0%] Tasks: 38, 174 thr, 3 running
2 [||| 4.2%] Load average: 0.42 0.59 0.54
Mem[|||||||||||||||||||||||||||||1.98G/3.86G] Uptime: 0d 09:45:39
Swp[ 0K/2.00G]
PID PRI NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1 root 20 0 4.2M 2.1M 1.1M S 0.0 0.1 19:14.47 init
2 root 20 0 0K 0K 0K S 0.0 0.0 0:00.00 kthreadd
3 root 20 0 0K 0K 0K I 0.0 0.0 0:00.01 rcu_gp
4 root 20 0 0K 0K 0K I 0.0 0.0 0:00.00 rcu_par_gp
6 root 20 0 0K 0K 0K I 0.0 0.0 0:00.01 kworker/0:0H
- The htop interface provides information about system load, memory usage, swap space, and a list of running processes.
- It also allows you to sort processes, search for processes, and interact with them (e.g., sending signals, killing processes).
How to exit htop command?
- To exit htop, you can press the q key, just like in top.
- You can navigate htop using keyboard shortcuts, and it’s a powerful tool for monitoring system performance and managing processes.
Free Linux command:
- Displays information about system memory, including total, used, and free memory.
- The free command is used to display information about system memory usage.
- It provides details about both physical and swap memory.
free:
Here’s an example of how to use the free command:
Open your terminal.
Simply type free and press Enter.
free
The free command will display memory statistics, including total, used, free, and cached memory.
Here’s an example of what the free display might look like:
total used free shared buff/cache available
Mem: 4048824 1242964 2471464 136044 3343962651464
Swap: 4194300 0 4194300
- In this example, the Mem section provides information about physical memory (RAM), including the total, used, free, shared, buffer/cache, and available memory.
- The Swap section provides information about swap space, including the total, used, and free swap space.
- The values are typically shown in kilobytes (KB), but you can use the -m option with the free command to display the values in megabytes, which can be more human-readable:
free -m Linux command
This will display the memory statistics in megabytes, making it easier to interpret.
Df Linux command:
- Shows disk space usage on mounted filesystems.
- The df command is used to display disk space usage for mounted file systems on a Linux system.
df:
Here’s an example of how to use the df command:
Open your terminal.
Simply type df and press Enter.
df
- The df command will display information about all mounted file systems, including the device or partition, the total space, the used space, the available space, and the mount point.
Here’s an example of what the df output might look like:
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda1 10321208 3350148 6434884 35% /
tmpfs 102400 4 102396 1% /dev
tmpfs 1024000 1496 1022504 1% /run
tmpfs 1024000 0 1024000 0% /dev/shm
tmpfs 1024000 0 1024000 0% /run/lock
tmpfs 1024000 0 1024000 0% /sys/fs/cgroup
In this example, the output displays information about various file systems.
The columns represent:
Filesystem: The device or partition name.
1K-blocks: The total disk space in 1-kilobyte blocks.
Used: The amount of space used.
Available: The amount of space available.
Use%: The percentage of space used.
Mounted on: The mount point of the file system.
- This information is useful for monitoring disk space usage on your system and identifying any potential issues with disk storage.
- You can use various options with the df command to format the output differently or focus on specific file systems.
- For example, you can use df -h to display sizes in a human-readable format (e.g., in gigabytes and megabytes).
du Linux command:
Estimates the disk usage of files and directories.
du:example
The du (disk usage) command is used to estimate the file and directory space usage on a Linux system.
Here’s an example of how to use the du command:
Open your terminal.
To check the disk usage of a specific directory, navigate to that directory using the cd command.
For example, if you want to check the disk usage of the /var/log directory, you would do:
cd /var/log
- Once you are in the directory you want to analyze, run the du command with optional flags to customize the output.
For example, you can simply type du to see the sizes of all files and directories within the current directory:
du Linux command
This will display a list of files and directories with their respective disk space usage.
If you want to see the sizes in a more human-readable format (e.g., in megabytes or gigabytes), you can use the -h option:
Linux command
- This will display sizes in a human-readable format.
- To sort the output by the size of the files and directories, you can use the sort command in combination with du.
For example, to see the top 10 largest items in the current directory:
du -h | sort -rh | head -n 10
- This will display the top 10 largest items within the directory.
- The du command can be very useful for finding large files or directories that are consuming a lot of disk space on your system.
- You can use it to identify where disk space is being used and manage your storage more effectively.
ifconfig or ip addr Linux command:
- Displays network interface configuration.
- The ifconfig and ip addr commands are used to display network interface configuration on a Linux system.
ifconfig or ip addr:
Here’s an example of how to use both commands to view network information:
Open your terminal.
To view network information using ifconfig, simply type:
ifconfig
This command will display information about all network interfaces on your system, including their IP addresses, MAC addresses, and more.
The output may look something like this:
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.100 netmask 255.255.255.0 broadcast 192.168.1.255
inet6 fe80::e0:24ff:fe56:78e4 prefixlen 64 scopeid 0x20<link>
ether 00:e0:24:56:78:e4 txqueuelen 1000 (Ethernet)
RX packets 18137 bytes 2675585 (2.5 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 11126 bytes 1313992 (1.2 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
To view network information using ip addr, type:
ip addr
- This command will also display information about network interfaces, including their IP addresses, MAC addresses, and more, but in a slightly different format.
The output may look something like this:
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP>
mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
inet 192.168.1.100/24 brd 192.168.1.255 scope global dynamic eth0
valid_lft 85556sec preferred_lft 85556sec
inet6 fe80::e0:24ff:fe56:78e4/64 scope link
valid_lft forever preferred_lft forever
- Both ifconfig and ip addr provide information about network interfaces, and which one to use may depend on your Linux distribution and personal preference.
- The ip command is more modern and recommended for more recent Linux distributions, but ifconfig is still widely supported and used on many systems.
Netstat Linux command:
Displays network statistics, routing tables, interface statistics, masquerade connections, and more.
netstat:example
- The netstat command is used to display network-related information on a Linux system.
- However, netstat has been deprecated in favor of the ss (Socket Statistics) command.
Here’s an example of how to use both netstat and ss:
Using netstat (deprecated):
Open your terminal.
To view network information using netstat, you can run the following command to display a list of network connections:
netstat -tuln
- This command will show a list of listening and established TCP and UDP network connections.
- The -t option displays TCP connections, the -u option displays UDP connections,
- The -l option shows only listening sockets.
- The -n option displays numerical addresses and port numbers instead of resolving hostnames.
Using ss (recommended):
Open your terminal.
To view network information using ss, you can run the following command to display a list of network sockets:
ss -tuln
- This ss command is similar to the netstat example above, displaying information about listening and established TCP and UDP network sockets.
- The -t, -u, -l, and -n options have the same meanings as in the netstat example.
- The primary difference between netstat and ss is that ss is more modern and generally more efficient.
- It’s recommended to use ss over netstat on recent Linux distributions.
- The example commands provided above will help you inspect network connections and sockets on your Linux system.
ss Linux command:
A replacement for netstat that shows socket statistics.
The ss (Socket Statistics) command is used to display detailed information about network sockets and connections on a Linux system.
Here’s an example of how to use the ss command:
ss:example
Open your terminal.
To view network socket information using ss, you can run the following command to display a list of network sockets:
ss
- This command will display a comprehensive list of network sockets, including established connections, listening sockets, and more.
- To filter the output to only show TCP connections, you can use the -t option:
ss -t
- This will display only TCP sockets.
- To filter the output to only show UDP connections, you can use the -u option:
ss -u
- This will display only UDP sockets.
To display listening sockets (servers), you can use the -l option:
ss -l
- This will show only listening sockets.
To display numerical addresses and port numbers instead of resolving hostnames, you can use the -n option:
ss -n
- This is especially useful for readability and performance.
Here’s an example of what the ss output might look like:
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 0.0.0.0:22 0.0.0.0:*
ESTAB 0 0 192.168.1.100:22 192.168.1.10:48512
ESTAB 0 0 192.168.1.100:22 192.168.1.11:39862
- The output provides details about the state, receive and send queues, local and peer addresses, and port numbers for each socket.
- The ss command is a powerful tool for inspecting network sockets and connections on your Linux system.
- You can combine various options to filter and customize the output based on your needs.
Lshw Linux command:
Lists hardware information about your system.
The lshw (List Hardware) command is used to list detailed hardware information about your system on a Linux system.
lshw:example
Here’s an example of how to use the lshw command:
Open your terminal.
To view hardware information using lshw, you can run the following command:
sudo lshw
- Running lshw without sudo may not display detailed information about some hardware components. You might need super privileges to access certain parts of the hardware.
- After running the command, lshw will start listing detailed information about your system’s hardware components, such as the CPU, memory, storage devices, network interfaces, and more.
Here’s an example of what the lshw output might look like:
*-memory
description: System Memory
physical id: 2
slot: System board or motherboard
size: 8GiB
*-bank:0
description: DIMM DDR3 Synchronous 1600 MHz (0.6 ns)
product: M471B5173EB0-YK0
vendor: Samsung
physical id: 0
serial: 3A0E54E3
slot: ChannelA-DIMM0
size: 4GiB
width: 64 bits
clock: 1600MHz (0.6ns)
…
*-network
description: Wireless interface
product: Wireless 7260
vendor: Intel Corporation
physical id: 0
bus info: pci@0000:02:00.0
logical name: wlp2s0
…
- The output will include detailed information about various hardware components on your system.
- You can use this information to identify your system’s hardware specifications, including CPU, memory, graphics, storage, and network interfaces.
- Keep in mind that the output from lshw can be quite extensive, and you may need to scroll through the terminal to view all the hardware details.
- You can also redirect the output to a file if you want to save the information for later reference:
sudo lshw > hardware_info.txt
This will save the hardware information in a text file named hardware_info.txt.
Lscpu Linux command: Displays CPU information.
The lscpu command is used to display detailed information about the CPU(s) on a Linux system.
lscpu:example
Here’s an example of how to use the lscpu command:
Open your terminal.
To view CPU information using lscpu, simply type:
lscpu
- This command will display information about the CPU(s) on your system, including details about the number of CPUs or cores, CPU architecture, model name, and more.
Here’s an example of what the lscpu output might look like:
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 4
On-line CPU(s) list: 0-3
Thread(s) per core: 2
Core(s) per socket:2
Socket(s): 1
NUMA node(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model: 78
Model name: Intel(R) Core(TM) i7-6500U CPU @ 2.50GHz
Stepping: 3
CPU MHz: 499.961
CPU max MHz: 3100.0000
CPU min MHz: 400.0000
BogoMIPS: 5184.00
Virtualization: VT-x
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 4096K
NUMA node0 CPU(s): 0-3
- The output provides information about the CPU’s architecture, operating mode, number of CPUs or cores, model name, clock speed, cache sizes, and more.
- The lscpu command is a valuable tool for understanding the characteristics of the CPU(s) in your system.
- It’s particularly useful for system administrators, programmers, and anyone interested in system performance.
lsblk Linux command:
Shows information about block devices (e.g., hard drives and SSDs).
The lsblk command is used to list block devices, such as hard drives, SSDs, and their respective partitions on a Linux system.
lsblk:example
Here’s an example of how to use the lsblk command:
Open your terminal.
To view block device information using lsblk, simply type:
lsblk
This command will display a hierarchical view of block devices, including their sizes, mount points, and more.
Here’s an example of what the lsblk output might look like:
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 238.5G 0 disk
├─sda1 8:1 0 512M 0 part /boot/efi
├─sda2 8:2 0 2G 0 part /boot
└─sda3 8:3 0 235.9G 0 part
└─root 253:0 0 235.9G 0 lvm /
sdb 8:16 0 1.8T 0 disk
├─sdb1 8:17 0 1.8T 0 part /mnt/data
sdc 8:32 0 250G 0 disk
- The output provides information about block devices, their major and minor numbers, size, read-only status, type, and mount points (if applicable).
- The lsblk command is helpful for identifying the storage devices and partitions on your system, allowing you to see how storage is organized and where devices are mounted.
- This information can be useful for disk management and system administration tasks
Lspci Linux command:
- Lists PCI devices on the system.
- The lspci command is used to display information about the PCI devices (Peripheral Component Interconnect) connected to your Linux system.
lspci:
Here’s an example of how to use the lspci command:
Open your terminal.
To view PCI device information using lspci, simply type:
lspci
- This command will list all the PCI devices, including details like the device’s vendor and model, the device’s ID, the subsystem, and more.
Here’s an example of what the lspci output might look like:
00:00.0 Host bridge:
Intel Corporation Xeon E3-1200 v6/7th Gen Core Processor Host Bridge/DRAM Registers (rev 05)
00:01.0 PCI bridge:
Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor PCIe Controller (x16) (rev 05)
00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 620 (rev 02)
00:04.0 Signal processing controller:
Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Thermal Subsystem (rev 05)
00:14.0 USB controller:
Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller (rev 21)
…
- The output provides information about PCI devices present on your system, including their vendor, device ID, and a description of the device.
- lspci is a valuable tool for identifying and understanding the PCI devices connected to your system, which can be useful for diagnosing hardware issues, finding the appropriate drivers, or verifying hardware compatibility.
Lsusb Linux command:
Lists USB devices on the system.
The lsusb command is used to list USB devices connected to a Linux system.
Here’s an example of how to use the lsusb command:
lsusb:
Open your terminal.
To view USB device information using lsusb, simply type:
lsusb
This command will list all the USB devices connected to your system, including their vendor and product IDs, device descriptions, and bus information.
Here’s an example of what the lsusb output might look like:
Bus 002 Device 001:
ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 006:
ID 0a12:0001 Cambridge Silicon Radio, Ltd Bluetooth Dongle (HCI mode)
Bus 001 Device 004:
ID 04f2:b40e Chicony Electronics Co., Ltd HD WebCam (Acer)
Bus 001 Device 003:
ID 046d:c534 Logitech, Inc. Unifying Receiver
Bus 001 Device 002: ID 05e3:0610 Genesys Logic, Inc. 4-port hub
Bus 001 Device 001:
ID 1d6b:0002 Linux Foundation 2.0 root hub
- The output provides information about the USB devices, including the bus and device numbers, vendor and product IDs, and a description of the device.
- lsusb is a useful tool for identifying USB devices connected to your system.
- It can help you verify that USB devices are recognized by your system and identify their specifications.
dmidecode Linux command:
- Provides information about the computer’s hardware components as reported by the BIOS/UEFI.
- The dmidecode command is used to retrieve hardware information from the system’s DMI (Desktop Management Interface) table.
- This table contains information about the system’s hardware components, such as the BIOS, motherboard, CPU, memory, and more.
dmidecode:example
Here’s an example of how to use the dmidecode command:
Open your terminal.
To view detailed hardware information using dmidecode, you can run the following command:
sudo dmidecode
Running dmidecode with sudo is often required to access certain parts of the DMI information.
After running the command, dmidecode will display an extensive list of hardware components and their details.
Here’s an example of what the dmidecode output might look like (the output is quite lengthy):
# dmidecode 3.3
Getting SMBIOS data from sysfs.
SMBIOS 2.8 present.
126 structures occupying 4426 bytes.
Table at 0x000E5100.
Handle 0x0000, DMI type 0, 24 bytes
BIOS Information
…
Handle 0x0010, DMI type 1, 27 bytes
System Information
…
Handle 0x1000, DMI type 16, 23 bytes
Physical Memory Array
…
Handle 0x1100, DMI type 17, 34 bytes
Memory Device
…
The output provides extensive information about the BIOS, system, memory, CPU, and other hardware components.
You can also use specific keywords to extract information about particular components.
For example, to get information about the BIOS, you can use:
sudo dmidecode –type bios
- dmidecode is a powerful tool for retrieving detailed hardware information, and it can be helpful for system administrators, diagnosing hardware issues, or ensuring hardware compatibility.
- The command allows you to access a wide range of hardware details, so you can specify which type of information you want to extract based on your needs.
lsmod Linux command:
- The lsmod command is used to display a list of currently loaded kernel modules on a Linux system.
- Kernel modules are pieces of code that can be dynamically loaded and unloaded into the Linux kernel to provide additional functionality or device support.
Lists currently loaded kernel modules.
lsmod:example
Here’s an example of how to use the lsmod command:
Open your terminal.
To view the list of currently loaded kernel modules, simply type:
lsmod
This command will list all the kernel modules along with their respective sizes, usage counts, and dependencies.
Here’s an example of what the lsmod output might look like:
Module Size Used by
nvidia 34763776 67
nvidia_drm 40960 6
nvidia_modeset 1196032 12 nvidia_drm
joydev 20480 0
uvcvideo 98304 0
videobuf2_vmalloc 16384 1 uvcvideo
videobuf2_memops 16384 1 videobuf2_vmalloc
btusb 53248 0
btrtl 20480 1 btusb
…
- The output provides information about each loaded kernel module, including the module’s name, size, and usage count.
- lsmod is a useful tool for inspecting which kernel modules are currently loaded on your system, which can be valuable for diagnosing hardware support or troubleshooting issues related to kernel modules.
ps Linux command:
Displays information about running processes.
ps:example
The ps command is used to view a list of currently running processes on a Linux system. It provides information about processes, such as their Process ID (PID), status, resource utilization, and more. Here’s an example of how to use the ps command:
Open your terminal.
To view a list of currently running processes using the default output format, simply type:
ps
Ps Linux command
This command will display a list of processes running in your current terminal session.
Here’s an example of what the ps output might look like (the actual output can vary depending on your system and the processes running):
PID TTY TIME CMD
5187 pts/0 00:00:00 bash
5233 pts/0 00:00:00 ps
- The output includes the Process ID (PID), the terminal associated with the process (TTY), the CPU time used by the process, and the command associated with the process.
To view a more detailed list of all processes, including those running in the background and owned by other s, you can use the following command:
ps aux Linux command
This command will provide a comprehensive list of processes along with details such as the who owns the process, CPU and memory utilization, and more.
ps aux
Here’s an example of what the ps aux output might look like (the actual output can be quite extensive):
PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
5187 0.0 0.0 20080 3876 pts/0 Ss Oct28 0:00 bash
5236 0.0 0.0 20428 3864 pts/0 R+ 11:49 0:00 ps aux
The output includes information about the who started the process, the PID, CPU and memory usage, the terminal (TTY) associated with the process, and more.
The ps command is a powerful tool for inspecting and monitoring processes running on your system. You can also use various options and filters with ps to display specific process information or customize the output format as needed.
who Linux command:
Shows who is logged into the system.
who:example
The who command is used to display information about s who are currently logged in to a Linux system. Here’s an example of how to use the who command:
Open your terminal.
To view a list of s who are currently logged in, simply type:
who
This command will display a list of names along with their terminal, login time, and originating IP address (if applicable).
Here’s an example of what the who output might look like:
pts/0 2023-10-28 08:30 (192.168.1.100)
guest pts/1 2023-10-28 09:15 (192.168.1.101)
- The output includes the name, terminal (TTY), login time, and the IP address from which the logged in.
- You can use who to check who is currently logged in to your system and which terminals they are using.
- This can be useful for system administration tasks or for monitoring activity on the system.
w Linux command:
Displays information about currently logged-in s.
w:example
The w command is used to display a list of currently logged-in s on a Linux system, along with information about their activities and the terminals they are using.
Here’s an example of how to use the w command:
Open your terminal.
To view a list of logged-in s and their activities, simply type:
w
- This command will display a list of s, their login times, terminal (TTY), remote IP addresses (if applicable), and the commands they are currently running.
Here’s an example of what the w output might look like:
09:00:17 up 1 day, 1:30, 2 s, load average: 0.08, 0.03, 0.05
TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
tty1 :0 08:30 1:30m 0.08s 0.01s bash
guest pts/1 192.168.1.101 09:15 0.00s 0.08s 0.02s ssh @hostname
- The output includes information about system uptime, the number of logged-in s, the load average, details, terminal (TTY), remote IP addresses (if applicable), login times, idle times, and the commands s are running.
- The w command is a valuable tool for monitoring activity and checking who is currently logged in to your system. It provides a more detailed overview of sessions compared to the who command.
uptime Linux command:
Shows how long the system has been running and the current system load.
uptime:example
- The uptime command is used to display the system’s current uptime and load averages.
- It provides information about how long the system has been running and the system load over the last 1, 5, and 15 minutes.
Here’s an example of how to use the uptime command:
Open your terminal.
To view the system’s uptime and load averages, simply type:
uptime
This command will display the current time, system uptime, and load averages.
Here’s an example of what the uptime output might look like:
09:00:17 up 1 day, 1:30, 2 s, load average: 0.08, 0.03, 0.05
- The output includes the current time, system uptime (1 day, 1 hour, and 30 minutes in this example), the number of logged-in s, and the system load averages (0.08, 0.03, and 0.05) for the last 1, 5, and 15 minutes, respectively.
- The uptime command is a useful tool for quickly checking how long your system has been running and whether it is experiencing high or low load.
- It’s handy for monitoring system performance and determining when the system was last restarted.
Date Linux command:
Displays the current date and time.
date:example
- The date command is used to display or set the system date and time on a Linux system. Here’s an example of how to use the date command:
Open your terminal.
To simply view the current system date and time, type:
date
- This command will display the current date and time in the default format.
Here’s an example of what the date output might look like:
Thu Oct 28 09:00:17 UTC 2023
- The output includes the day of the week, month, day, time, timezone (in this case, UTC), and the year.
- To set the system date and time, you can use the –set option followed by the desired date and time in the format YYYY-MM-DD HH:MM:SS.
For example, to set the system date and time to October 1, 2023, at 15:30:00, you can use the following command (you’ll need super privileges):
sudo date --set "2023-10-01 15:30:00"
- Make sure to replace the date and time in the command with the desired values.
- The date command is essential for managing system date and time settings. It can also be used in scripts to generate timestamps or perform time-related tasks.
cat /proc/cpuinfo Linux command:
Provides detailed CPU information.
cat /proc/cpuinfo:example
- To view detailed information about the CPU(s) on your Linux system, you can use the cat command to display the contents of the /proc/cpuinfo file.
Here’s an example of how to do this:
Open your terminal.
To view the CPU information, simply type:
cat /proc/cpuinfo
- This command will display detailed information about the CPU(s) on your system.
Here’s an example of what the cat /proc/cpuinfo output might look like (the actual output can vary depending on your system’s hardware):
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 94
model name : Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz
stepping : 3
microcode : 0xd6
cpu MHz : 3327.347
cache size : 6144 KB
physical id : 0
siblings : 8
core id : 0
cpu cores : 4
apicid : 0
initial apicid : 0
fpu : yes
fpu_exception : yes
cpuid level : 22
wp : yes
………..
- The output provides information about the CPU, including its model, vendor, clock speed, cache size, and various CPU features and flags.
- /proc/cpuinfo is a virtual file that provides detailed information about the CPU(s) on your system.
- This information can be valuable for understanding your hardware configuration and optimizing system performance.
cat /proc/cpuinfo :example
Here’s an example of using the cat command to display the contents of the /proc/cpuinfo file, which provides detailed information about the CPU(s) on your Linux system:
Open your terminal.
To view the CPU information, simply type:
cat /proc/cpuinfo
This command will display detailed information about the CPU(s) on your system.
Here’s an example of what the cat /proc/cpuinfo output might look like (the actual output can vary depending on your system’s hardware):
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 142
model name : Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz
stepping : 9
microcode : 0x84
cpu MHz : 800.000
cache size : 6144 KB
physical id : 0
siblings : 8
core id : 0
cpu cores : 4
apicid : 0
initial apicid : 0
fpu : yes
fpu_exception : yes
cpuid level : 22
wp : yes
flags : ……
bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs
bogomips : 5600.00
clflush size : 64
cache_alignment : 64
address sizes : 39 bits physical, 48 bits virtual
power management:
- The output provides information about the processor, including details such as the model, vendor, clock speed, cache size, CPU features, and more.
- The /proc/cpuinfo file is a virtual file that provides detailed information about the CPU(s) on your system.
- This information can be useful for understanding your hardware configuration, optimizing system performance, and checking for specific CPU features.
cat /proc/version Linux command:
Shows the Linux kernel version.
The /proc/version file provides information about the kernel version and build details of your Linux system.
You can use the cat command to display the contents of this file.
cat /proc/version:example
Here’s an example:
Open your terminal.
To view the kernel version and build information, simply type:
cat /proc/version
This command will display information about the kernel version, build date, and other relevant details.
Here’s an example of what the /proc/version output might look like (the actual output can vary depending on your system and kernel version):
Linux version 5.4.0-90-generic (buildd@lgw01-amd64-037) (gcc version 9.3.0 (Ubuntu 9.3.0-13ubuntu1)) #101-Ubuntu SMP Tue Nov 30 12:01:41 UTC 2021
The output includes information about the Linux kernel version, compiler version, and various details related to the kernel’s build.
/proc/version is a useful file for checking the kernel version on your system, which can be important for compatibility and troubleshooting.
ls /proc:
Explore the /proc directory for various system-related information.
ls /proc:example
The /proc directory in Linux contains a wealth of information about the system, processes, and kernel parameters. To list the contents of the /proc directory, you can use the ls command. However, keep in mind that the directory contains numerous entries, and I’ll provide you with an example that shows a few entries:
Open your terminal.
To list the contents of the /proc directory, simply type:
ls /proc
This command will display a list of files and directories inside the /proc directory.
Here’s an example of what the ls /proc output might look like (a subset of the entries):
1 156 16 189 2580 2588 2590 2598
2606 2613 2632 2637 2643 2734 2759
2760 2763 2767 2769 2771 2776 2778
2783 2785 2786 2787 2788 2789 2790
……
dmesg Linux command:
Displays kernel ring buffer messages, which can provide information about hardware and system events.
The dmesg command is used to display kernel ring buffer messages, which can contain information about the kernel, hardware, drivers, and system events. To view the kernel messages, you can use the dmesg command in your terminal.
dmesg:example
Here’s an example:
Open your terminal.
To view the kernel messages, simply type:
dmesg
This command will display the kernel messages, and you can scroll through them to see detailed information about the system, hardware, and kernel events.
Here’s an example of what the dmesg output might look like (a portion of the messages):
[ 0.000000] Linux version 5.4.0-90-generic
….
[ 0.000000] KERNEL supported cpus:
[ 0.000000] Intel GenuineIntel
[ 0.000000] AMD AuthenticAMD
[ 0.000000] Hygon HygonGenuine
[ 0.000000] Centaur CentaurHauls
[ 0.000000] zhaoxin Shanghai
[ 0.000000] Disabled fast string operations
…
The output includes kernel version information, boot parameters, CPU details, and various kernel messages.
dmesg is a valuable tool for diagnosing hardware issues, reviewing system events, and checking for kernel-related problems.
You can search for specific messages within the output to help troubleshoot system problems or monitor kernel activity.
cat /proc/meminfo:
Displays information about system memory.
cat /proc/meminfo
Quiz with answers
1-Which Linux command is used to display detailed information about the CPU(s) on a Linux system?
a) date
b) lsusb
c) lscpu
d) lsmod
Correct Answer: c) lscpu
2-What command should you use to view information about currently loaded kernel modules on a Linux system?
a) lsmod
b) lsusb
c) dmesg
d) top
Correct Answer: a) lsmod
2-Which command is used to display the system’s current uptime and load averages?
a) who
b) uptime
c) date
d) w
Correct Answer: b) uptime
3-What command displays a list of currently logged-in s on a Linux system along with their activities?
a) ls
b) ps
c) who
d) w
Correct Answer: d) w
4-Which command provides information about the kernel version and build details of a Linux system?
a) uname
b) cat /etc/os-release
c) date
d) cat /proc/version
Correct Answer: d) cat /proc/version
5-Which command is used to retrieve hardware information from the system’s DMI table?
a) lsusb
b) lspci
c) dmidecode
d) cat /proc/cpuinfo
Correct Answer: c) dmidecode
6-What command displays a list of USB devices connected to a Linux system?
a) lscpu
b) lsusb
c) lsmod
d) df
Correct Answer: b) lsusb
7-Which command provides detailed information about currently running processes on a Linux system?
a) who
b) uptime
c) w
d) ps
Correct Answer: d) ps
8-Which command is used to display the Linux distribution and version information?
a) uname
b) cat /etc/os-release
c) lsb_release
d) cat /proc/version
Correct Answer: b) cat /etc/os-release
9-What command displays a list of currently mounted filesystems on a Linux system?
a) lsblk
b) mount
c) df
d) lsusb
Correct Answer: b) mount
10-Which command provides information about the network interfaces and their configuration on a Linux system?
a) ifconfig
b) ip addr
c) netstat
d) lshw
Correct Answer: b) ip addr
11-What command is used to display information about the listening network sockets and routing tables on a Linux system?
a) netstat
b) ifconfig
c) ip addr
d) ss
Correct Answer: a) netstat
12-Which command is used to display information about the memory usage on a Linux system, including total, used, and free memory?
a) lsusb
b) lshw
c) free
d) top
Correct Answer: c) free
13-What command provides information about block devices such as hard drives and partitions on a Linux system?
a) lscpu
b) lsblk
c) df
d) cat /proc/cpuinfo
Correct Answer: b) lsblk
14-Which command is used to display a list of currently loaded kernel modules on a Linux system?
a) lsusb
b) lspci
c) lsmod
d) lscpu
Correct Answer: c) lsmod
15-What command should you use to display the system’s current date and time?
a) dmesg
b) cat /proc/version
c) uptime
d) date
Correct Answer: d) date
16-Which command is used to show a list of USB devices connected to a Linux system?
a) lscpu
b) lsusb
c) lsmod
d) w
Correct Answer: b) lsusb
17-What command is used to display detailed information about the currently running processes on a Linux system?
a) who
b) uptime
c) top
d) ps
Correct Answer: d) ps
18-Which command provides information about the system’s hostname?
a) uname
b) hostname
c) who
d) lsb_release
Correct Answer: b) hostname
19-What command is used to display information about network interfaces, including IP addresses, on a Linux system?
a) ifconfig
b) netstat
c) lshw
d) ip addr
Correct Answer: d) ip addr
20-Which command is used to view detailed information about the currently mounted filesystems on a Linux system, including device names and mount points?
a) mount
b) df
c) lsblk
d) lscpu
Correct Answer: b) df
21-What command provides information about the system’s hardware, including details about the CPU, memory, and peripheral devices?
a) lshw
b) lsblk
c) dmesg
d) w
Correct Answer: a) lshw
22-Which command is used to display a list of available PCI devices and their details on a Linux system?
a) lsusb
b) lsmod
c) lspci
d) cat /proc/cpuinfo
Correct Answer: c) lspci
23-What command is used to show information about currently active and established network connections on a Linux system?
a) ss
b) ip addr
c) netstat
- d) dmesg
Correct Answer: a) ss
24-Which command is used to display detailed information about the system’s memory usage, including physical and swap memory?
a) free
b) top
c) lsusb
d) lscpu
Correct Answer: a) free
References
- Linux Forums and Communities: Websites like Stack Exchange’s Unix & Linux Stack Exchange, LinuxQuestions.org, and various subreddits dedicated to Linux are excellent places to ask questions and find information.
- Linux Tutorials and Blogs: Websites like Linuxize, TecMint, and Linux Journal often publish tutorials and articles on Linux-related topics.
- Linux Books: There are many books available on Linux administration and commands. Some well-regarded titles include “Linux Pocket Guide” by Daniel J. Barrett and “The Linux Command Line” by William E. Shotts, Jr.