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If you want to explore the secrets of Linux systems, here is a treasure trove of practical commands! From basic system information to hardware, disk, processes, network, and user information, all kinds of commands are included. For example, use <span>uname</span> to check the kernel version, and <span>top</span> for real-time process monitoring. Mastering them will allow you to easily gain insights into the system and embark on a journey of efficient management and troubleshooting!
01Comprehensive Guide to Linux System Information Commands
In Linux systems, there are many useful commands that can help us understand various information about the system. Below is a detailed introduction to these commands.
Basic System Information
uname
<span>uname</span> command can display basic information about the system, such as kernel name, hostname, kernel version, etc.
•Common parameters:•<span>-a</span>: Display all information.•<span>-r</span>: Display kernel version.•Example:
123456789# Display all information
uname -a
# Output example
Linux myhost 5.4.0-109-generic #123-Ubuntu SMP Fri Apr 8 16:08:38 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
# Display only kernel version
uname -r
# Output example
5.4.0-109-generichostname
<span>hostname</span>
The command is used to display or set the system’s hostname.
•Example:
10111213141516# Display current hostname
hostname
# Output example
myhost
# Set hostname (requires root privileges)
sudo hostname newhostlsb_release
<span>lsb_release</span> command can display information about the Linux distribution.
•Common parameters:•<span>-a</span>: Display all information.•Example:
17181920212223
lsb_release -a
# Output example
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04.4 LTS
Release: 20.04
Codename: focalHardware Information
lshw
<span>lshw</span> command is used to display hardware information of the system, including CPU, memory, disk, etc.
•Common parameters:•<span>-short</span>: Display information in a short format.•Example:
24252627282930313233343536# Display all hardware information (requires root privileges)
sudo lshw
# Display information in short format
sudo lshw -short
# Output example
H/W path Device Class Description
=====================================================/0 system Computer
/0/0 bus Motherboard
/0/0/0 memory 64KiB BIOS
/0/0/100 bridge 4thGenCoreProcessor DRAM Controller
/0/0/100/1 bridge Xeon E3-1200 v3/4thGenCoreProcessor PCI Express x16 Controller
/0/0/100/1/0 display GK107 [GeForce GT 640]lscpu
<span>lscpu</span> command is used to display information related to the CPU.
•Example:以下视频来源于熊小白玩数码
37383940414243444546474849505152535455565758596061
lscpu
# Output example
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
ByteOrder: 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: 60
Model name: Intel(R) Core(TM) i5-4200U CPU @ 1.60GHz
Stepping: 3
CPU MHz: 2394.000
BogoMIPS: 5184.00
Hypervisor vendor: VMware
Virtualization type: full
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 3072K
NUMA node0 CPU(s): 0-3lsblk
<span>lsblk</span> command is used to list block device information, such as hard drives, USB drives, etc.
•Example:
62636465666768697071
lsblk
# Output example
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 1K 0 part
└─sda5 8:5 0 237.9G 0 part ├─vgubuntu-root 252:0 0 230.9G 0 lvm /
└─vgubuntu-swap_1 252:1 0 7G 0 lvm [SWAP]
sr0 11:0 1 1024M 0 romfree
<span>free</span> command is used to display memory usage of the system.
•Common parameters:•<span>-h</span>: Display information in a human-readable format.•Example:
72737475767778798081828384# Display memory usage
free
# Output example
total used free shared buff/cache available
Mem: 8165920 2248340 4787700 75020 1129880 5477440
Swap: 7340028 0 7340028
# Display in human-readable format
free -h
# Output example
total used free shared buff/cache available
Mem: 7.8G 2.2G 4.6G 73M 1.1G 5.2G
Swap: 7.0G 0B 7.0GDisk Usage Information
df
<span>df</span> command is used to display disk usage of the file system.
•Common parameters:•<span>-h</span>: Display information in a human-readable format.•Example:
858687888990919293949596979899100101102103104105106107108109# Display disk usage
df
# Output example
Filesystem 1K-blocks Used Available Use% Mounted on
udev 4031000 0 4031000 0% /dev
tmpfs 816592 8472 808120 2% /run
/dev/mapper/vgubuntu-root 242087936 15573880 214328840 7% /
tmpfs 4082944 2500 4080444 1% /dev/shm
tmpfs 5120 4 5116 1% /run/lock
tmpfs 4082944 0 4082944 0% /sys/fs/cgroup
/dev/sda1 523248 67208 456040 13% /boot/efi
tmpfs 816592 40 816552 1% /run/user/1000
# Display in human-readable format
df -h
# Output example
Filesystem Size Used Avail Use% Mounted on
udev 3.9G 0 3.9G 0% /dev
tmpfs 798M 8.3M 790M 2% /run
/dev/mapper/vgubuntu-root 231G 15G 205G 7% /tmpfs 3.9G 2.5M 3.9G 1% /dev/shm
tmpfs 5.0M 4.0K 5.0M 1% /run/lock
tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup
/dev/sda1 512M 66M 447M 13% /boot/efi
tmpfs 798M 40K 798M 1% /run/user/1000du
<span>du</span> command is used to estimate the disk usage of files or directories.
•Common parameters:•<span>-h</span>: Display information in a human-readable format.•<span>-s</span>: Display only the total.•Example:
110111112113114115116117118119120121# Display disk usage of each subdirectory in the current directory
du
# Display in human-readable format
du -h
# Display total of the current directory
du -s
# Display total in human-readable format
du -sh
# Output example
4.0K ./test
8.0K ./data
12K .Process Information
ps
<span>ps</span> command is used to display the current status of processes.
•Common parameters:•<span>-e</span>: Display all processes.•<span>-f</span>: Display process information in full format.•Example:
122123124125126127128129130131132133134135# Display current user's processes
ps
# Output example
PID TTY TIME CMD
1234 pts/0 00:00:00 bash
1235 pts/0 00:00:00 ps
# Display full information of all processes
ps -ef
# Output example
UID PID PPID C STIME TTY TIME CMD
root 1 0 0 00:00:00 /sbin/init splash
root 2 0 0 00:00:00 [kthreadd]
root 3 2 0 00:00:00 [rcu_gp]top
<span>top</span> command is a dynamic tool for displaying real-time system process information.
•Example:
136topAfter running the <span>top</span> command, you will enter an interactive interface that displays real-time information about the system, including CPU and memory usage, as well as detailed information about each process. You can sort and filter by pressing different keys. Press the <span>q</span> key to exit the <span>top</span> interface.
htop
<span>htop</span> is a more powerful and intuitive process monitoring tool than <span>top</span>. You need to install the <span>htop</span> package first (the installation method varies by system; for example, on Ubuntu, you can use <span>sudo apt install htop</span> to install).
•Example:
137htop<span>htop</span> has a more beautiful interface, clearer information display, and can also monitor system process information in real-time, with mouse operation support.
Network Information
ifconfig
<span>ifconfig</span> command is used to display or configure network interface information.
•Example:
138139140141142143144145146147148149150151152153154155156ifconfig
# Output exampleeth0: 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::a00:27ff:fe12:3456 prefixlen 64 scopeid 0x20<link> ether 08:00:27:12:34:56 txqueuelen 1000 (Ethernet) RX packets 1000 bytes 123456 (123.4 KB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 500 bytes 67890 (67.9 KB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10<host> loop txqueuelen 1000 (Local Loopback) RX packets 10 bytes 1200 (1.2 KB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 10 bytes 1200 (1.2 KB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0ip
<span>ip</span> command is a more powerful alternative to <span>ifconfig</span>.
•Example:
157158159160161162163164165166167168169170171# Display all network interface information
ip addr show
# Output example
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 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 fq_codel state UP group default qlen 1000 link/ether 08:00:27:12:34:56 brd ff:ff:ff:ff:ff:ff inet 192.168.1.100/24 brd 192.168.1.255 scope global dynamic eth0 valid_lft 86399sec preferred_lft 86399sec inet6 fe80::a00:27ff:fe12:3456/64 scope link valid_lft forever preferred_lft forevernetstat
<span>netstat</span> command is used to display network connections, routing tables, network interface statistics, etc.
•Common parameters:•<span>-t</span>: Display TCP connections.•<span>-u</span>: Display UDP connections.•<span>-n</span>: Display addresses and port numbers in numeric form.•<span>-l</span>: Display listening connections.•Example:
172173174175176177178# Display all TCP listening connections
netstat -tnl
# Output example
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp6 0 0 :::22 :::* LISTENUser Information
who
<span>who</span> command is used to display information about users currently logged into the system.
•Example:
179180181182who
# Output example
user1 pts/0 2023-09-10 10:00 (192.168.1.101)
user2 pts/1 2023-09-10 10:30 (192.168.1.102)w
<span>w</span> command is used to display information about users currently logged into the system, as well as what they are doing.
•Example:
183184185186187188w
# Output example
10:45:00 up 1:45, 2 users, load average: 0.00, 0.01, 0.05
USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
user1 pts/0 192.168.1.101 10:00 0.00s 0.05s 0.00s w
user2 pts/1 192.168.1.102 10:30 0.00s 0.00s 0.00s bashid
<span>id</span> command is used to display user identity information, including user ID, group ID, etc.
•Example:
189190191id
# Output example
uid=1000(user1) gid=1000(user1) groups=1000(user1),4(adm),24(cdrom),27(sudo),46(plugdev),116(lpadmin),126(sambashare)These are the commonly used information commands in Linux systems, which allow for a comprehensive understanding of various system information,
facilitating system management and troubleshooting.