9 Common commands

This chapter will introduce the common commands when using the basic version of core electronic devices, advanced general-purpose chips and basic software products desktop operating system, hereinafter referred to as the CAB desktop OS. In this document, all commands will be used in the terminal. The terminal is the interface for human-computer interaction and all commands will be executed in it.

The open mode of the basic version of desktop terminal: Click the "Terminal" button on the taskbar in the desktop to open a terminal. The terminal interface is shown below.


 

9.1 File and directory management

9.2 File and directory search

9.3 File system management

9.4 System process management

9.5 Network management

9.6 Software management

9.1 File and directory management

(1) "ls" List the contents of the directory (List)

"ls" is of high frequency use as a command. The following sections are only a part of the most common use of options. If you want to play a greater measure of “ls” command,please check its help page“ls”—help.
ls [Option] File or directory ...
ls common options:
               -l                 Output file attributes in long list format
               -R                 Recursively listed,traverses the entire directory and its       subdirectories
--color=[WHEN]   According to the property of the output file    (file or directory type, etc.), give the project a different color
                                   The value of WHEN can be 'always' (default), 'never', 'auto',
                                   Meanings in turn are: always, never, automatic
               -d                Only lists the directory, does not list the contents of the directory
               -h                Humanized output, such as using the format   K, M, G to mark the file size
Examples of usage:
               ls              List the contents of the current directory
               ls -Rl /home     List the details of all files in the /tmp directory and its subdirectories

(2) cd Change working Directory

cd [Directory path]  # If the directory path is omitted, it will enter the user's home directory.
Examples of usage:
                cd /tmp
                cd ~            # enter the user's home directory. In the bash shell, the symbol "~" indicates the user's home directory
                cd              # Omit the path, also enter the user's home directory

(3) touch Create a text file

If the file needs to be created that has already existed,then updates file access time and modification time to the current time.
touch [Option] file name 1 ...
Examples of usage:
                touch file1     # If the file1 file does not exist, then create a text file named file1.
                                      # Otherwise update its access time and modification time.

(4) cat View the contents of the text file (Concatenate)

If there are multiple files, then output to the standard output in turn.  It is equivalent to the contents of several files connected.
cat [Option] file name 1 ...
cat Common options:
                -n      Display line number
Examples of usage:
                cat /etc/issue      # Output the contents of the file / etc / issue to the standard output

(5) cp File and directory copy (Copy)

cp [Option] Source file Target file
cp common options:
                -r Recursively copy, that is, copy the entire directory
                -v Output the information of copy process
                -i If the target file already exists, the default action will overwrite the target file. This option requests the user to confirm
                -n Do not copy files that already exist
                -u Copy files that are newer than the target file
Examples of usage:
                cp testfile testfile1 # Copy the file named testfile in the current directory and renames the file as testfile1.
                cp -r dir1 down # Copy the directory named dir1 in the current directory to the down directory

(6)mv File move and rename (Move)

The "mv" command is similar to the file copy command "cp". The difference between them is that if you use "mv" command, the source file will be deleted after completing the operation.
Attention:The mv command does not have a recursive option –r. There is no difference between moving directories and moving normal files.
mv [option] Source file  Target file
The common options of mv command:
                -i      By default, mv will overwrite the source file, and this option requests the user to confirm.
                -n      Do not move the existing files.
                -u      Only move the files that are newer than the target file
                -v      Display detailed movement process
Examples of usage:
                mv -vi file1 file2   # Move files interactively. Move files in the same directory, and actually it renames the file.

(7) mkdir Make Directory

If the directory you want to create that has already exists, then do nothing about it.
mkdir [option] Directory name 1 ...
The common options of mkdir command:
                -p|--parents    When it is necessary, build parent directory
                -m                  Set permissions for the created directory
                -v                   Output the details of the current operation
Examples of usage:
                mkdir -pv a/b/c   # Will be a/b/c hierarchical structure to establish three directories which are named a b c in turn.
                                           # Due to the use of the-p option, if a or b directory does not exist, then it will be automatically established together.
                                          # If you do not use -p, the system will report an error when the parent directory does not exist
                mkdir a b c         # Establish three directories named a b c in the current directory.

(8) rm Delete a file or directory (Remove)

rm [option] file or directory ...
rm common options:
                -f      Mandatory mode      Never prompt, and does not require user confirmation
                -i      Interactive mode       Ask users to confirm before deleting the file
                -r      Recursively delete    Delete the entire directory
                -v      Outputs the details of the current operation
Examples of usage:
                rm -vi  file1        # Delete the file file1
                rm -vir dir1        # Delete the directory dir1

(9) rmdir Delete empty directory (Remove Rirecotry)

If the directory is not empty, the system prompts the error, does not delete the directory
rmdir [option]  empty directory ...
rmdir common options:
                -p|--parents   If you delete the directory, the parent directory has become an empty directory, then delete it.
                -v              Output the details of the current operation.
Examples of usage:
                rmdir -pv a/b/c  # Delete the empty directory c, and if the b directory is empty, then delete the b directory,... 

9.2 File and directory search

(1) find Search for files

The find command is very powerful and supports regular expressions
find Command commonly used to write:
find [option] path [other options]
The common options of find command:
            -P              Do not follow the symbolic link, that is, ignore the file that the symbolic link points to
            -L              Follow the symbolic link

The other common used options of find command:
                -type <file_type>         Find the specified file type, can be f (common file), d (directory file),c(Character device file),...
                -name <file_name>      Find a specific file. It is sensitive to the capital and small letter of the file.
                -iname <file_name>    Same as –name, but ignore the capital and small letter of the file.
                -maxdepth level            Specify the maximum number of directories to search for(the number of layers), and level is a specific positive number                                                                                                                                                                                                                                                       
-mindepth level             Specify the minimum directory level to search for and level is a specific positive number
                -size [-/+] <file_size>  Limit the size of the search file, file_size is a specific number,the unit can be c w b k M G.
                The "-" or "+" sign before the number indicates that the file size is "less than" or "greater than" the number
                Omitting  "-" or "+" indicates that the file size is strictly for the number.
                -regex pattern   Using regular expressions to search for the files. Pattern is the file name expression.
                -regextype type  Setting the standard of resolving regular expression. Type optional values are emacs (default)  posix-awk, posix-egrep, posix-extended
                -exec command \;    Executive a command.  The contents after -exec are resolved as a part of the command until encounter ";" because the semicolon has special meaning in the Bash Shell, so use the slash "\" escape.
Examples of usage:
                find . -type f                   # Find all the files in the current directory
                find ~ -name .bashrc       # Find a file named ".bashrc" in the user directory
                find /usr -type f -iname "*conf*"
                # Ignore case to find the files with the file name contains "conf" in the directory /usr
                find /usr -size +100K -size -2M -regextype posix-egrep -regex ".*png$"
                # In the /usr directory, find the files whose file size are between 2kB to 2MB and the last three letters of the file name are png.
                find ~ -type d -size +40M -exec file {} \;
                # find the files that the file size is more than 40MB in the user directory, and use the file command to check its type.

9.3 File system management

(1) df List file system usage

df [option] [file] ...
df Common options:
                -a                      Output all file systems
                -h                      User-friendly output information
                -t <fs_type>      Only output the  file system type which is  limited by fs_type
                -T                      Output file system type
Examples of usage:
                df -ht ext4         #Output file system with the  type of ext4
                df -T                  # Output file system type
                df -h /dev/sda1  # Output the usage information of the first partition for the first hard disk

(2) fdisk Disk partition management

This command requires users with privileged user permission
fdisk [option] disk
The common options of fdisk:
            -v Print fdisk version information and exit
            -l List the partition table information for the specified device and exit. If it doesn’t offer device, then use the devices which are mentioned in / proc / partitions.
            -u Use the number of sectors rather than cylinders to display each partition information in the partition table
            -s Output the size of the partition (in blocks) to the standard output.
Examples of usage: fdisk -l # Output the detailed partitioning information of all hard disks in the current system. fdisk /dev/sda # Enter the hard disk split mode 1.input m Show all commands listed 2.input p Show hard disk segmentation 3. input a Set the hard disk boot area 4. input n Set the new hard disk partition 5. Input t Change the hard disk partition properties 6. input d Delete the hard disk partition properties 7. input q End and does not save the hard disk partition properties 8. input w End and save the hard disk partition properties

(3) mkfs Format the disk

This command requires the permission of privileged user
mkfs [option] Partition The common options of mkfs command: -t Specify the formatted file system type -c Check whether there is a bad block or not before formatting the file system block Specify the size of the block
Examples of usage: mkfs -t ext3 /dev/sda6 #Format the /dev/sda6 partition with the ext3 file type

(4) du Calculate the size of the file / directory

du [option]  directory or file ...
The common options of du command:
                -h       User-friendly output. The file size is marked by K, M, G
                -s        Output the total occupancy space size of each directory/file
Examples of usage:
                du -h  ~  # Output the total occupancy space size of all files and subdirectories in the user's home directory

(5) mount Mount the file system

This command requires the permission of privileged user
mount [option] device target directory
The common options  of mount command:
                -t              Specify the file system type, such as ext3, ext4 and so on
                -B             Mount directory
Examples of usage:
                mount                                       # List all mounted file systems
                mount -t ext4 /dev/sda6 /mnt  # Mount the sixth partition of the first hard disk to the /mnt directory
                mount -B /media /mnt              # mount the directory /media to the directory /mnt 

(6) umount uninstall the file system

This command requires the permission of privileged user
umount [option] device or directory ...
The common option of unmount command:
                -f              Force to uninstall the directory
Examples of usage:
                umount  /dev/sda6                 # Uninstall the mounted file system /dev/sda6

9.4 System process management

(1) "top" Display the real-time process list

Once the command top is run, then press the "q" key to exit.
               top [option]
               The common options of top command:
               -p pidlist        Only shows dynamic process whose process number in pslist
               -d num            Update interval. Num is the time, Unit is second (s)
Examples of usage:
                top -d 1 -p 1,2     # Only two processes with process numbers 1 and 2 are monitored and the information is updated once per second

(2) ps List the processes that the current system is running

 The command ps accepts three types of options. Some options are conflicting, and some options gets the same function, increasing the difficulty of usage
ps [option]
The common options of ps command:
                -e                display all processes
                -a                List all processes except the session's first process and the process of unassigned the terminal
                -u userlist     Use the user ID or user name to select the listed process, ID or name in the userlist
                -p pidlist        Only list processes that specify the process number in the pidlist, which can be used multiple times
                --ppid pidlist   Only lists the child processes of the process number that is in pidlist
                -x              List the processes that belong to the current user
                -ax            List all processes. Here 'x' is used in conjunction with 'a' and no other options are available

Examples of usage:
                ps aux oracle           # Query oracle process
                ps --ppid 1              # Lists the process whose parent process is 1

(3) ps List the processes that the current system is running

Pidof Find the process number (pid) based on the process name
pidof  [option] process name
The common options of pidof:
                -s              pidof output the process number as many as possible by the process name, the option is limited that only to output one process number.
Examples of usage:
                pidof lightdm

(4) kill Send a signal to the process

kill [option] pidlist
The common options of kill command:
                -l List the signal name
                -s signal Specify the signal to be sent, the default is 15
Examples of usage: kill -s 9 <PID> # PID is the specific process number (using the pidof command to find), the signal 9 is the kill process.

(5) killall kill process

killall Kill the process by name
killall [option] process name
The common options of killall command:
                -l     List all known signal names
                -v      Report whether the signal is sent successfully
Examples of usage: killall gedit # Kill all processes which named "gedit"

9.5 Network management

(1) ifconfig View / set the network (Interface Configure)

This command requires user with the permission of privileged user
 ifconfig setting the network will not be saved, and all changes will disappear after restarting.
 Linux network interface can be understood as a network card, cable network card number: eth0 eth1...;Wireless card number:wlan0 wlan1 ...
 ifconfig [option]  [network interface]
 ifconfig network interface [Protocol address cluster] Option address ...  
The common options of ifconfig:
                -a                  display all network interfaces
                up                  open the network interface
                down             close the network interface
                netmask         set the mask
                broadcast       set the broadcast address
Examples of usage: ifconfig -a # Displays all network interface information ifconfig eth0 192.168.1.10 netmask 255.255.255.0 broadcast 192.168.1.254 The above command sets the wired network card IP address to 192.168.1.10, the subnet mask is 255.255.255.0, the broadcast address is 192.168.1.254 ifconfig eth0 down # Close Network card eth0 ifconfig eht0 up # Open Network card eth0

(2) ping The host computer sends the packet

Test the connectivity of the network
ping [option] Host
The common option of ping:
                -c      By default, the ping is running until the user presses Ctrl+C to abort.The option limits the time of ping.
Examples of usage:
                ping -c 5 127.0.0.1 # Test whether the native TCP/IP protocol is normal or not, 127.0.0.1 has been configured to represent the native machine

(3) netstat View the network status (Network Status)

netstat [option] The common options of netstat: -p display process information -t Only list the entries associated with the tcp protocol -u Only list the entries associated with the udp protocol -n Port, address, etc. use numbers instead of name display -a display all -l only display entries in the listening state
Examples of usage: netstat -atunp # display all the process that use tcp and udp protocol, and the communication address, port number

9.6 software management

(1) dpkg Package management tool

This command requires user with the permission of privileged user
dpkg is used to manage the system deb package. You can install, uninstall, deb package, deb decompress the system deb package and so on.
dpkg [option] deb package
The  common options of dpkg:
                -i  Install the software package
                -r  Remove the software package
                -P  Delete the package (including the configuration file)
                -l  List the packages that are currently installed on the system
Examples of usage: dpkg -i cheese-common_3.10.1-1sid1_all.deb # The installation of the video camera package dpkg -r libmcrypt4 # Uninstall the software package

(2) apt-get Management tool

This command requires user the permission of privileged user
Apt-get is mainly used to automatically search, install, upgrade, and uninstall software or operating system from the Internet's software depot.
apt-get [option] command pkg
The common command of apt-get:
                update     Retrieve the package list
                upgrade  Update the package
                install     Install new packages
                remove   Remove the package
                auto remove  Automatically remove all unused packages
Examples of usage: apt-get upgrade # Update the installed packages apt-get install wine # Install the wine program apt-get remove kolourPaint # Remove the kolourPaint software from the system