150 common commands you must know in Linux operation and maintenance

Linux commands are the core of Linux system management, similar to DOS commands. There are two types of commands in Linux systems: built-in Shell commands and Linux commands. These commands manage the CPU, memory, disk drives, etc., and are necessary for the normal operation of the system.

The

Order	Function Description
Online query and help commands (2)
man	View command help, command dictionary, more complex ones include info, but they are not commonly used.
help	View help for Linux built-in commands, such as the cd command.
File and directory operation commands (18)
ls	Quan spell list, the function is to list the contents of the directory and its content attribute information.
cd	Quanpin change directory, the function is to switch from the current working directory to the specified working directory.
cp	Quan spelling copy, its function is to copy files or directories.
find	Search means, used to find directories and files under directories.
mkdir	Quanpin make directories, its function is to create directories.
mv	Quan spell move, its function is to move or rename files.
pwd	Quanpin print working directory, its function is to display the absolute path of the current working directory.
rename	is used to rename files.
rm	Quanpin remove, its function is to delete one or more files or directories.
rmdir	Quanpin remove empty directories, the function is to delete empty directories.
touch	Create a new empty file and change the timestamp attribute of the existing file.
tree	The function is to display the contents of the directory in a tree structure.
basename	Display file name or directory name.
dirname	Display file or directory path.
chattr	Change the extended attributes of the file.
lsattr	View file extension attributes.
file	Display the type of file.
md5sum	Calculate and verify the MD5 value of the file.
View file and content processing commands (21)
cat	Quanpin concatenate, the function is to connect multiple files and print to the screen output or redirect to the specified file.
tac	tac is the reverse spelling of cat, so the function of the command is to display the file contents in reverse.
more	Display file contents in pages.
less	Display the file contents in pages, the opposite usage of the more command.
head	Display the header of the file content.
tail	Display the end of the file content.
cut	Split each line of the file according to the specified delimiter and output it.
split	Split the file into different small fragments.
paste	Merge file contents line by line.
sort	Sort the text content of the file.
uniq	Remove duplicate rows. oldboy
wc	Count the number of lines, words or bytes of the file.
iconv	Convert the encoding format of the file.
dos2unix	Convert DOS format files to UNIX format.
diff	Quan spelling difference, compares the differences of files, often used for text files.
vimdiff	Command line visual file comparison tool, often used for text files.
rev	Reverse output file content.
grep/egrep	Filter string, the third of the Three Musketeers.
join	Merge by the same fields in the two files.
tr	Replace or delete characters.
vi/vim	Command line text editor.
File compression and decompression commands (4)
tar	Package and compress. oldboy
unzip	unzip files.
gzip	gzip compression tool.
zip	Compression tool.
Information display commands (11)
uname	Command to display operating system related information.
hostname	Display or set the host name of the current system.
dmesg	Displays boot information and is used to diagnose system faults.
uptime	Display system running time and load.
stat	Display the status of a file or file system.
du	Calculate disk space usage.
df	Report file system disk space usage.
top	Real-time display of system resource usage.
free	View system memory.
date	Display and set system time.
cal	View calendar and other time information.
Search file commands (4)
which	Search for binary commands and search according to the path of the environment variable PATH.
find	Traverse the disk to find files or directories.
whereis	Search for binary commands and search according to the path of the environment variable PATH.
locate	Find the command from the database (/var/lib/mlocate/mlocate.db) and use updatedb to update the library.
User management commands (10)
useradd	Add user.
usermod	Modify user attributes that already exist in the system.
userdel	delete users.
groupadd	Add user group.
passwd	Change user password.
chage	Modify the user password validity period.
id	View the user's uid, gid and user group.
su	Switch user identity.
visudo	Exclusive command to edit /etc/sudoers file.
sudo	Execute commands previously allowed in the sudoers file as another user (default root user).
Basic network operation commands (11)
telnet	Use TELNET protocol to log in remotely.
ssh	Use SSH encryption protocol to log in remotely.
scp	Quanpin secure copy, used to copy files between different hosts.
wget	Command line download file.
ping	Test the network connectivity between hosts.
route	Display and set the routing table of the linux system.
ifconfig	Commands to view, configure, enable or disable network interfaces.
ifup	Start the network card.
ifdown	Close the network card.
netstat	Check network status.
ss	Check network status.
In-depth network operation commands (9)
nmap	Network scan command.
lsof	Full name list open files, which is to list the files that have been opened in the system.
mail	Send and receive emails.
mutt	Mail management commands.
nslookup	Command to interactively query Internet DNS servers.
dig	Find the DNS resolution process.
host	Query DNS command.
traceroute	Track data transmission routing status.
tcpdump	Command line packet capture tool.
Commands related to disk and file system (16)
mount	Mount the file system.
umount	Unmount the file system.
fsck	Check and repair Linux file system.
dd	Convert or copy files.
dumpe2fs	Export ext2/ext3/ext4 file system information.
dump	ext2/3/4 file system backup tool.
fdisk	Disk partition command, applicable to disk partitions below 2TB.
parted	Disk partition command has no disk size limit and is commonly used for disk partitions below 2TB.
mkfs	Format to create a Linux file system.
partprobe	Update the kernel’s hard disk partition table information.
e2fsck	Check ext2/ext3/ext4 type file system.
mkswap	Create Linux swap partition.
swapon	Enable swap partition.
swapoff	Close the swap partition.
sync	Write the data in the memory buffer to disk.
resize2fs	Adjust the size of the ext2/ext3/ext4 file system.
System permissions and user authorization related commands (4)
chmod	Change file or directory permissions.
chown	Change the owner and group of a file or directory.
chgrp	Change the file user group.
umask	Display or set permission mask.
Commands to view system user login information (7)
whoami	Display the currently valid user name, which is equivalent to executing the id -un command.
who	Display the user information currently logged into the system.
w	Display the list of users who have logged in to the system and display the instructions that the user is executing.
last	Display users logged into the system.
lastlog	Display the latest login information of all users in the system.
users	Display the user list of all users currently logged in to the system.
finger	Find and display user information.
Built-in commands and others (19)
echo	Print variables, or directly output the specified string
printf	Format the results and output them to standard output.
rpm	Commands to manage rpm packages.
yum	Automate and simplify the management of rpm package commands.
watch	Periodically execute the given command and display the output of the command in full screen mode.
alias	Set system alias.
unalias	Cancel system alias.
date	View or set the system time.
clear	Clear the screen, referred to as clear screen.
history	View the history of command execution.
eject	Eject the optical drive.
time	Calculate command execution time.
nc	Powerful network tool.
xargs	Convert standard input into command line parameters.
exec	The command to call and execute the instruction.
export	Set or display environment variables.
unset	Delete variables or functions.
type	Used to determine whether another command is a built-in command.
bc	Command line scientific calculator
System management and performance monitoring commands (9)
chkconfig	Manage Linux system startup items.
vmstat	Virtual memory statistics.
mpstat	Display status statistics of each available CPU.
iostat	Statistics system IO.
sar	Comprehensively obtain the system's CPU, run queue, disk I/O, paging (swap area), memory, CPU interrupt and network performance data.
ipcs	Used to report the status of inter-process communication facilities in Linux. The information displayed includes message list, shared memory and semaphore information.
ipcrm	Used to delete one or more message queues, semaphore sets or shared memory identifiers.
strace	Used to diagnose and debug Linux user space tracker. We use it to monitor the interaction between user space processes and the kernel, such as system calls, signal transmission, process state changes, etc.
ltrace	command will track the library function calls of the process, and it will show which library function is called.
Commands to shut down/restart/log off and view system information (6)
shutdown	Shut down.
halt	Shut down.
poweroff	Turn off the power.
logout	Quit the currently logged in Shell.
exit	Quit the currently logged in Shell.
Ctrl d	Shortcut key to exit the currently logged in Shell.
Process management related commands (15)
bg	Convert a command that is paused in the background to continue execution (execute in the background).
fg	Move the command in the background to the foreground to continue running.
jobs	Check how many commands are currently running in the background.
kill	Terminate the process.
killall	Terminate the process by process name.
pkill	Terminate the process by process name.
crontab	Scheduled task command.
ps	Display a snapshot of the process.
pstree	Tree display process.
nice/renice	Adjust the priority of program running.
nohup	Ignore the pending signal and run the specified command.
pgrep	Find processes matching the conditions.
runlevel	View the current running level of the system.
init	Switch run level.
service	Start, stop, restart and shut down system services, and also display the current status of all system services.

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