The following shell commands in the Linux system

I. File, directory Operation command

1. ls command

Features: Displays information about files and directories

LS Displays the list of current directory files by default

Ls-a Show all files including hidden files

Ls-l display file attributes, including size, date, symbolic connection, whether read-write and executable

LS-LH Show file size, print file size in easy-to-understand format (e.g. 1K 234m2g)

LS-LT display files, sorted by modified time

2. CD command

Function: Renaming directory

cd dir switch to dir directory in current directory

CD/Switch to root directory

Cd.. Switch to the top level directory

Cd..　/.. Switch to the top level two directory

CD ~ Switch to the user directory, such as the root user, then switch to/root

3. CP command

Function: Copy file

CP Source target copies the file source to target

Cp/root/source. Copy the file source under/root to the current directory

Cp–av soure_dir target_dir Copy the entire directory, both directories are exactly the same

4. RM command

Features: Deleting files or directories

RM file Deletes a file

Rm-f file deletion is not prompted. Can be used with the R parameter

RM-RF dir Delete the entire directory called Dir in the current directory

5. MV Command

Function: Move the file away, or change the name, under the Uinx not renamed the command, if you want to rename, you can use the command

MV Source Target renames the file source to target

6. diff

Function: Compare file contents

Diff Dir1 Dir2 compares the file list of directory 1 with directory 2, but does not compare the actual contents of the file, but lists

diff file1 File2 Compare file 1 with the contents of file 2 is the same, if it is a text format of the file, it will be different content display, if the binary code only means that two files are not the same

Comm file1 file2 comparison file showing two different files

7. LN command

Features: Establish links. The shortcut to Windows is based on the principles of the link.

ln source_path Target_path Hard Connection

Ln-s source_path Target_path Soft Connection

Second, view the file Contents command

1. Cat commands

Displays the contents of the file, the same as the DOS type

Cat file

2. More Commands

Features: Pagination display commands

More file

The more command can also be passed through the pipe character (|) Used with other commands, such as:

PS Ux|more

Ls|more

3. Tail command

Function: Displays the last few lines of the file

Tail-n aaa.txt display the last 100 lines of a file Aaa.txt file

4. VI Command

VI File Edit files

VI Original BASIC use and command:

Enter the command by pressing the [ESC] key first, and then entering: w (write to file): w! (Do not ask the way to write the file): Wq Save and exit,: Q Quit, q! do not save the exit

5. Touch command

Function: Create an empty file

Touch Aaa.txt creates an empty file with a file name of Aaa.txt

Iii. Basic System commands

1. Man command

function: Check the help of a command, if you do not know the use of a command do not understand, you can ask him, he knows to tell you back

For example:

Man LS display Help content for LS command

2, W command

Features: Displays details of the logged-on user

For example:

sarge:~# W

22:06:51 up min, 1 user, Load average:0.00, 0.00, 0.00

USER TTY from [email protected] IDLE jcpu PCPU

Zhoulj pts/0 10.140.0.109 21:24 0.00s 0.85s 0.09s sshd:zhoulj [Priv]

3. Who command

Features: Show logged in user

For example:

sarge:~# who

Zhoulj pts/0 Mar 13 21:24 (10.140.0.109)

4. Last Order

Features: View recent User Login Systems

For example:

sarge:~# Last

Zhoulj pts/0 10.140.0.109 Mon Mar 21:24 still logged in

Reboot system boot 2.6.8-2-386 Mon Mar 13 21:23 (00:43)

Zhoulj pts/0 10.140.0.105 Sun Mar 22:51-down (00:00)

Zhoulj pts/0 10.140.0.105 Sun Mar 12 22:51-22:51 (00:00)

Root tty1 Sun Mar 22:50-down (00:01)

Root tty1 Sun Mar 12 22:46-22:48 (00:02)

Root tty1 Sun Mar 12 22:43-22:46 (00:02)

Reboot system boot 2.6.8-2-386 Mon Mar 13 06:34 ( -7:-41)

Wtmp begins Mon Mar 13 06:34:11 2006

5. Date command

Function: System Date setting

Date Displays the current date time

Date-s 20:30:30 Set the system time to 20:30:30

Date-s 2002-3-5 Set the system period for 2003-3-5

Date-s "060520 06:00:00" sets the system period to May 20, 2006 6 o'clock full.

6. Clock command

function: Clock setting

Clock–r read time parameters in the system BIOS

Clock–w writes the system time (such as the time set by date) to the BIOS

7. uname command

Function: View System version

Uname-r shows the version of the operating system kernel

For example:

sarge:~# uname-a

Linux Sarge 2.6.8-2-386 #1 Tue 12:46:35 UTC 2005 i686 Gnu/linux

8. Shutting down and restarting system commands

Reboot restart your computer

Shutdown-r Now restarts the computer, stops the service, and then restarts the computer

Shutdown-h now shut down the computer, stop the service, and then shut down the system

Halt shutting down the computer

Generally with Shutdown-r now, in rebooting the system is to close the related services, Shutdown-h now is also the case.

9. su command

Function: Switch User

Su-Switch to root user

SU-ZHOULJ switch to ZHOULJ user,

Note:--he is critical, using--that will use the user's environment variable

Iv. Monitoring System Status commands

1. Top command

Features: View system CPU, memory and other usage

2. Free command

Function: view memory and swap partition usage

For example:

sarge:~# Free-tm

Total used free shared buffers Cached

mem:187 42 145 0 6 16

-/+ buffers/cache:19 167

swap:243 0 243

total:430 42 388

3, uptime

Function: The current time, the system is running to the time elapsed now, the number of users connected, the last minute, five minutes and 15 minutes of system load

For example:

sarge:~# Uptime

21:54:46 up to Min, 1 user, Load average:0.00, 0.00, 0.00

4. Vmstat command

Function: Monitor virtual memory usage

For example:

# Vmstat

Procs Memory Swap IO system CPU

R b swpd free buff cache si so bi bo in CS US sy ID WA

1 0 0 63704 8100 32272 0 0 8 3 103 17 0 1 98 1

5. PS command

Function: Show process information

PS UX shows the current user's process

PS uxwww Show details of the current user's process

PS aux shows process for all users

PS EF Display system all process information

6. Kill command

Function: Kill a process, the process number can be obtained through the PS command

Kill-9 1001 Kill a program with process number 1001

Kill all-9 Apache kills all programs named Apapche, Kill is not omnipotent, and the zombie program is invalid.

Five, disk Operation command

1. DF command

function: Check the disk space consumption of the file system. You can use this command to get information about how much space the hard disk is taking up, and how much space is left.

Parameter function

-A Lists all directories

-TA Lists all directories and displays file types

-B Display block information

-I list all directories with the I node

-H Display according to daily habits (e.g. 1K, 100M, 20G)

-X [Filesystype] does not display [Filesystype]

For example:

# df-th

Filesystem Type Size used Avail use% mounted on

/DEV/SDA1 ext3 265M 64M 187M 26%/

Tmpfs tmpfs 94M 0 94M 0%/dev/shm

/dev/sda6 ext3 714M 8.1M 667M 2%/Home

/dev/sda8 ext3 956M 215M 691M 24%/usr

/DEV/SDA7 ext3 714M 57M 619M 9%/var

2. du command

Function: Detects a directory and (recursively) the disk space occupied by files in all its subdirectories.

Parameter function

-S [dirName] displays the total space occupied by the directory

-sk [DirName] Display directory occupies total space, in K units

-SB [DirName] Displays the total space occupied by the directory, in units B

-SM [DirName] Displays the total space occupied by the directory, in M

-SC [DirName] Displays the total space occupied by the directory, plus the catalog statistics

-sh [DirName] statistics only directory size

For example:

# DU-SH/ETC

1.3m/etc

3. Mount command

Features: Use the mount command to mount various file systems in Linux.

Format: MOUNT-T device name mount point

(1), mount/dev/sda1/mnt/filetest

Mount-t Vfat/dev/hda/mnt/fatfile

Mount-t Ntfs/dev/hda/mnt/ntfsfile

Mount-t Iso9660/dev/cdrom/mnt/cdrom

Mount-o Device Name Mount point

(2), using USB device

Modprobe Usb-storage

Mkdir/mnt/usb

Mount-t Auto/dev/sdx1/mnt/usb

Umount/mnt/usb

4. Mkswap command

Function: Use the MKSWAP command to create swap spaces, such as:

debian:~# mkswap-c/DEV/HDA4

debian:~# swapon/dev/hda4 #启用新创建的swap空间, disable the Use Swapoff command

5. fdisk command

Function: Partitioning the disk

fdisk/dev/xxx format xxx device (XXX refers to the name of the disk drive, for example, HDB,SDC)

FDISK-L display the partition table of the disk

6. MKFS command

Function: Format file system, you can specify the type of file system, such as ext2, ext3, FAT, NTFS, etc.

Format 1:mkfs.ext3 options/dev/xxx

Format 2:mkfs-t ext2 options/dev/xxx

Parameter function

-B Block Size

-I node capitalization

-m reserved administrative space size

For example:

debian:~ #mkfs. ext3/dev/sdb1

7. E2fsck command

Features: Disk detection

E2FSCK/DEV/HDA1 Check/dev/hda1 If there is a file system error, prompt repair method

E2fsck-p/dev/hda1 Check/dev/hda1 If there is an error, if any, fix it automatically

E2fsck-y/dev/hda1 Check error, all questions are executed in Yes mode

E2fsck-c/dev/hda1 Check if the disk has a bad zone

8. TUNE2FS command

Function: Adjust the parameters of the Ext2/ext3 file

Parameter function

-L View File system Information

-C Set the number of forced self-test mounts

-I set the mandatory self-test interval, per day

-m reserved percentage of blocks

-j converting ext2 file system to EXT3 format

# tune2fs-l/DEV/SDA1

9. DD Command

function: function: Copy the specified input file into the specified output file, and can be converted in format during the copy process.

Similar to the DOS diskcopy command.

DD if=/dev/fd0 of=floppy.img Copy the contents of the floppy disk into one image

DD if=floppy.img of=/dev/fd0 Copy the contents of an image to a floppy disk, which is often used when making a drive disk.

Vi. user and group related commands

1. Groupadd command

Features: Adding groups

Groupadd test1 Add test1 Group

Groupadd-g 1111 test2 add test2 Group with group ID 1111

2. Useradd command

Features: Adding users

Useradd user1 Add user user1,home to/home/user1, group User1

Useradd-g test1-m-d/home/test1 test1 Add user test1,home to/home/test1, group Test1

User list shows logged-in users

3. passwd command

Function: Change user password

passwd user1 modify password for user User1

Passwd-d root deletes the root user's password

4. Userdel command

Function: Delete User

Userdel User1 Delete user1 user

5. Chown command

Function: Change the owner of a file or directory

Chown User1/dir Set the/dir directory to user1 all

Chown-r User1.user1/dir will/dir all files and directories under the directory, set to User1 all, group User1. -R recursion to each file and directory below

6. CHGRP command

Function: Change all groups of files or directories

Chgrp User1/dir Set the/dir directory to user1 all

7. chmod command

Function: Change user's permissions

chmod a+x file to set the file to executable, the script class file must be set this way, otherwise you have to use bash file to execute

chmod 666 file is set to read/write

chmod the file is set to, the owner is the full permission, the same group can read and execute, other no permissions

8. ID command

Function: Display the user's information, including UID, GID, etc.

# ID ZHOULJ

uid=500 (ZHOULJ) gid=500 (ZHOULJ) groups=500 (ZHOULJ)

9. Finger command

Function: Display the information used

Note: There is no such command under Debian.

# finger Zhoulj

Login:zhoulj Name:

Directory:/home/zhoulj Shell:/bin/bash

On since Sun 07:59 (CST) on pts/0 from 192.168.1.4

No Mail.

No Plan.

Seven, compression command

1. gzip Format command

Features: Compressed files, GZ format

Note: The resulting file will overwrite the source file

Gzip-v compress files and show progress

-D Decompression

Gnuzip-f Decompression

For example:

# gzip A.sh

#ll

-rwxr-xr-x 1 root root 71 December 21:08 a.sh.gz

# gzip-d A.sh.gz

#ll

-rwxr-xr-x 1 root root 48 December 21:08 a.sh

2. zip Format command

Function: Compress and decompress zip commands

Zip

Unzip

For example:

# Zip A.sh.zip a.sh

adding:a.sh (stored 0%)

# LL

-rw-r--r--1 root root 188 May 10:37 A.sh.zip

# Unzip A.sh.zip

Archive:a.sh.zip

Replace a.sh? [Y]es, [N]o, [A]ll, [N]one, [R]ename:r

New name:a1.sh

extracting:a1.sh

# LL

-rwxr-xr-x 1 root root 48 December 21:08 a1.sh

3. Bzip2 Radical Command

Function: bzip2 format compression command,

Note: The resulting file will overwrite the source file

Bzip2

Bunzip2

For example:

# bzip2 A.sh

# LL

-rwxr-xr-x 1 root root 85 December 21:08 a.sh.bz2

# BUNZIP2 A.SH.BZ2

# LL

-rwxr-xr-x 1 root root 48 December 21:08 a.sh

4. Tar command

Function: archive, compress, etc., more important, will be used frequently.

-CVF compressing files or directories

-XVF unzip a file or directory

-ZCVF compressed file or, format tar.gz

-ZXVF unzip the file or, format tar.gz

-ZCVF compressed file or, format tgz

-ZXVF unzip the file or, format tgz

Example:

# tar CVF abc.tar *.sh

# tar XVF Abc.tar

# tar CZVF abc.tar.gz *.sh

# LL

-rw-r--r--1 root root 20480 May 10:50 Abc.tar

-rw-r--r--1 root root 1223 May 10:53 abc.tar.gz

# tar XZVF abc.tar.gz

Eight, network-related commands

1. Ifconfig command

Function: Display information to modify NIC

Ifconfig Displaying network information

Ifconfig eth0 display eth0 Network information

To modify network information:

Ifconfig eth0 192.168.1.1 netmask 255.255.255.0 Set the address of the network card 1 192.168.1.1, the mask is 255.255.255.0

Ifconfig Eth0:1 192.168.1.2 The second address of the bundled NIC 1 is 192.168.1.2

Ifconfig eth0:x 192.168.1.N Bundle NIC 1 The nth address is 192.168.1.N

For example:

# ifconfig Eth0:1 192.168.1.11

# ifconfig

Eth0 Link encap:ethernet HWaddr 00:0c:29:06:9c:24

inet addr:192.168.1.5 bcast:192.168.1.255 mask:255.255.255.0

Up broadcast RUNNING multicast mtu:1500 metric:1

RX packets:4220 errors:0 dropped:0 overruns:0 frame:0

TX packets:3586 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:1000

RX bytes:342493 (334.4 KB) TX bytes:469020 (458.0 KB)

Interrupt:9 Base address:0x1400

Eth0:1 Link encap:ethernet HWaddr 00:0c:29:06:9c:24

inet addr:192.168.1.11 bcast:192.168.1.255 mask:255.255.255.0

Up broadcast RUNNING multicast mtu:1500 metric:1

Interrupt:9 Base address:0x1400

2. Route command

Features: Displays current routing settings

The route shows the current routing settings, which is slower and less common.

Route add-net 10.0.0.0 netmask 255.255.0.0 GW 192.168.1.254 add static route

Route del-net 10.0.0.0 netmask 255.255.0.0 GW 192.168.1.254 add static route

Route add default GW 192.168.1.1 Metric1 set 192.168.1.1

Route del default deletes the defaults

Example:

# route add-net 10.0.0.0 netmask 255.255.0.0 GW 192.168.1.254

# NETSTAT-NR

Kernel IP Routing Table

Destination Gateway genmask Flags MSS Window Irtt Iface

192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0

10.0.0.0 192.168.1.254 255.255.0.0 UG 0 0 0 eth0

169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0

0.0.0.0 192.168.1.254 0.0.0.0 UG 0 0 0 eth0

# route del-net 10.0.0.0 netmask 255.255.0.0 GW 192.168.1.254

# NETSTAT-NR

Kernel IP Routing Table

Destination Gateway genmask Flags MSS Window Irtt Iface

192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0

169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0

0.0.0.0 192.168.1.254 0.0.0.0 UG 0 0 0 eth0

3. Netstat command

Function: Display network status

Netstat-an Viewing network port information

NETSTAT-NR View the routing table information, much faster than the route,

4, the command to start the network

Commands of the Redhat family:

/etc/init.d/network

Debian command:

/etc/init.d/networking

For example:

/etc/init.d/network Stop Stop Network,

/etc/init.d/network Start Network,

5, manually modify the network configuration

(1), Debian system

The configuration file location is:/etc/network/interfaces

# The Loopback network interface

Auto Lo

Iface Lo inet Loopback

# The Primary network interface

Auto Eth0 eth1

Iface eth0 inet Static

Address 10.4.5.6

Netmask 255.255.255.0

Network 10.4.5.0

Broadcast 10.4.5.255

Iface eth1 inet Static

Address 219.25.5.60

Netmask 255.255.255.192

Network 219.25.5.0

Broadcast 219.25.5.63

Gateway 219.25.5.30

After you save the configuration after you modify it, run

/etc/init.d/networking restart

The network configuration is changing

(2), Redhat system

The configuration file location is:/etc/sysconfig/network-scripts/ifcfg-eth0

Device=eth0

Bootproto=static

broadcast=192.168.1.255

ipaddr=192.168.1.5

netmask=255.255.255.0

network=192.168.1.0

gateway=192.168.1.254

Onboot=yes

Type=ethernet

After you save the configuration after you modify it, run

/etc/init.d/network restart

Or

Service Network restart

The network configuration is changed.

The location of the default DNS file is:/etc/resolv.conf

#cat/etc/resolv.conf

Search test.com.cn

NameServer 192.168.1.11

6. Network troubleshooting

(1), ping command

Function: Do not say, do not know to use dry this line.

Ping

(2), traceroute command

Features: route tracking

Traceroute

Traceroute 207.68.173.7

(3), nslookup command

Function: Domain name resolution troubleshooting

For example:

$ nslookup

Note:nslookup is deprecated and may removed from the future releases.

Consider using the ' dig ' or ' host ' programs instead. Run nslookup with

The '-sil[ent ' option to prevent this message from appearing.

>

server:192.168.1.11

address:192.168.1.11#53

Non-authoritative Answer:

Name:

address:202.118.66.66

> Server 202.118.66.6

Default server:202.118.66.6

address:202.118.66.6#53

>

server:202.118.66.6

address:202.118.66.6#53

Non-authoritative answer:canonical name =

.

Name:

address:202.108.22.5

Ix. Other Orders

1. SSH command

Function: remote login to other UNIX hosts

Ssh-l user1 192.168.1.2 Login to 192.168.1.2 using user name User1

Ssh

Login to 192.168.1.2 using username user1

2. SCP command

Features: Secure copy

For example:

SCP abc.tar.gz

: ~ Copy the local abc.tar.gz to the root of the 192.168.1.5 user1 user (/home/user1).

3. telnet command

Function: Login to remote host

For example:

Telnet 192.168.1.5

If you can't read it, there's another

Common directives

LS Display file or directory

-l list File details L (list)

-a lists all files and directories under the current directory, including Hidden A (all)

mkdir Creating a Directory

-P Create directory, if no parent directory, create p (parent)

CD Switch Directory

Touch creates an empty file

Echo creates a file with content.

Cat View File Contents

CP Copy

MV Move or rename

RM Delete File

-R Recursive Delete, can delete subdirectories and files

-F Force Delete

Find searches a file system for a file

WC statistics Text line number, word count, number of characters

Grep finds a string in a text file

RmDir Delete Empty Directory

Tree structure display directory, need to install tree package

PWD Displays the current directory

LN creates a linked file

More, less pagination displays text file contents

Head, tail display file header, tail content

CTRL+ALT+F1 command line full-screen mode

System administration Commands

Stat Displays details of the specified file, more detailed than LS

Who shows online login

WHOAMI Show current Operation user

Hostname Display host name

Uname Display System Information

Top dynamic display currently consumes the most resources process information

PS Display transient process status Ps-aux

Du view directory size Du-h/home with units display directory information

DF View disk size df-h with unit display disk information

Ifconfig Viewing network conditions

Ping Test network connectivity

Netstat Displaying network status information

Man command won't work, find men like: Guy ls

Clear Clear Screen

Alias renamed the Command as: Alias showmeit= "Ps-aux", in addition to de-use Unaliax Showmeit

Kill kills the process, you can first view the process ID with the PS or Top command, and then kill the process with the kill command.

Packaging compression-related commands

Gzip:

BZIP2:

Tar: Packaging compression

-C Archive File

-X Compressed file

-Z gzip Compressed file

-j bzip2 Compressed Files

-V shows the compression or decompression process V (view)

-F Use file name

Cases:

TAR-CVF/HOME/ABC.TAR/HOME/ABC only packaged, not compressed

TAR-ZCVF/HOME/ABC.TAR.GZ/HOME/ABC packaged and compressed with gzip

TAR-JCVF/HOME/ABC.TAR.BZ2/HOME/ABC packaged and compressed with bzip2

Of course, if you want to decompress, just replace the above command TAR-CVF/TAR-ZCVF/TAR-JCVF "C" in the "X".

Shut down/Restart the machine

Shutdown

-R shutdown Restart

-H shutdown does not restart

Now turn the machine off.

Halt shut down the machine

Reboot restart

Linux Pipelines

Use the standard output of one command as the standard input for another command. That is, the combination of several commands to use, the latter command in addition to the results of a previous command.

Example: Grep-r "Close"/home/* | More in the home directory to find all files, including close files, and paging output.

Linux Package Management

Dpkg (Debian package) management tool with a. deb suffix. This approach is suitable for systems that are not networked.

For example, install the tree command installation package, first upload tree.deb to the Linux system. Then install it using the command below.

sudo dpkg-i tree_1.5.3-1_i386.deb installation software

sudo dpkg-r tree Uninstall software

Note: There are several ways to upload tree.deb to a Linux system. Vmwaretool, use of Mount mode, use of WINSCP tools, etc.;

APT Advanced Packaging Tool. This method is suitable for the system to be able to connect the internet situation.

Still take tree as an example

sudo apt-get install tree

sudo apt-get remove tree unload tree

sudo apt-get update software

sudo apt-get upgrade

Convert. rpm files to. deb files

. RPM is the software format used by Redhat. cannot be used directly under Ubuntu, so you need to convert it.

sudo alien abc.rpm

Vim use

Vim three modes: Command mode, insert mode, edit mode. Use ESC or I or: to toggle the mode.

Command mode:

: Q exit

: q! Force exit

: Wq Save and exit

: Set number Displays line numbers

: Set Nonumber hidden line number

/apache find Apache in the document press N to jump to the next, Shift+n previous

YYP Copy the cursor line, and paste

H (move left one character ←), J (next line ↓), K (previous line ↑), L (move right one character →)

User and User group management

/etc/passwd Storing user accounts

/etc/group Storage Group Account

/etc/shadow Store password for user account

/etc/gshadow Password to store user group account

Useradd User Name

Userdel User Name

AddUser User Name

Groupadd Group Name

Groupdel Group Name

passwd root sets the password for root

Su Root

Su-root

/etc/profile System Environment variables

Bash_profile User Environment variables

. BASHRC User Environment variables

SU user switches the user and loads the configuration file. bashrc

Su-user switch User, load configuration file/etc/profile, load Bash_profile

User and user groups for changing files

sudo chown [-r] Owner[:group] {file| Directory}

For example: Also take jdk-7u21-linux-i586.tar.gz as an example. belongs to user Hadoop, group Hadoop

You want to switch the users and groups to which this file belongs. You can use commands.

sudo chown root:root jdk-7u21-linux-i586.tar.gz

File Rights Management

Three basic permissions

R read value represented as 4

The W write value is represented as 2

X executable value represented as 1

, the permissions for the jdk-7u21-linux-i586.tar.gz file are-rw-rw-r--

-rw-rw-r--altogether 10 characters, divided into four segments.

The first character "-" indicates a normal file, and the "L" link may also appear in this location; "D" means the directory

The No. 234 character "rw-" represents the permissions of the currently owned user. So the value is expressed as 4+2=6

The No. 567 character "rw-" represents the permissions for the group that is currently owned. So the value is expressed as 4+2=6

The No. 890 character "r--" represents other user rights. So the value is represented as 2

So the permission to manipulate this file is represented by a value of 662

Change permissions

sudo chmod [u belongs to user g belongs to group O Other User a All users] [+ Increase permissions-reduce permissions] [r W x] directory name

For example: There is a file filename, the permission is "-rw-r----x", the permission value is changed to "-rwxrw-r-x", with a numeric representation of 765

sudo chmod u+x g+w o+r filename

The above example can be represented by a numerical value

sudo chmod 765 filename

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The following shell commands in the Linux system