How Linux views common commands such as process, kill process, start process, etc.

Keywords: Linux check process, kill process, START process

1. Check process

The PS command finds the PID number associated with the process:

PS A shows all programs under the current terminal, including other users ' programs.

Ps-a Show All Programs.

PS C shows the actual instruction name of each program when the program is listed, not including the path, parameter, or indication of the resident service.

Ps-e the effect of this parameter is the same as specifying the "A" parameter.

When you list a program, PS e displays the environment variables that are used by each program.

PS F Displays the tree structure with ASCII characters and expresses the relationship between the programs.

PS-H displays a tree structure that represents the inter-program relationship.

Ps-n shows all the programs except the ones that perform the PS command terminal.

PS s uses program signal format to display program status.

PS S lists programs, including interrupted sub-program data.

ps-t< Terminal number > Specify the terminal number, and list the status of the program belonging to the terminal.

PS U Displays the status of the program in a user-oriented format.

PS x shows all the programs, not the terminal to distinguish.



The most common method is PS aux, which is then filtered by the grep command to find a particular process and then operate on a particular process.

PS aux | grep program_filter_word,ps-ef |grep Tomcat



Ps-ef|grep java|grep-v grep shows all the Java processes and places the current grep process away.



2. Killing process

To end a process with the KILL command: Kill XXX

Freq used: kill-9 324

Linux also provides a killall command that directly uses the name of the process rather than the process identification number, for example: # killall-9 Name



3. Go to the path where the execution file of the process is located, execute the file./File name



Report:



This is the time I spent two days to tidy up, some of the most commonly used by the Earth people know the order is omitted! Finally, PDF brochure is available for download



1. Change the owner of the file

Command: Chown [-CFHVR] [--help] [--version] user[:group] File ...

Function: Change the owner of a file or folder

Parameter format:

User: The user of the new file owner idGROUP: The user group of the new file owner (group)

C: If the file owner has changed, the change action is displayed

-F: Do not display an error message if the owner of the file cannot be changed

-H: Changes to the link only, not the file that the link really points to

-V: Show details of owner changes

-R: Same owner change for all files in the current directory and subdirectories (i.e., one by one in a recursive way)



Example: Chown-r oracle:oinstall/oracle/u01/app/oracle

Change the directory owner to Oracle



2. Modify Permissions

Command: chmod (change mode)

Function: Change the file read and write and execute permissions. Signed method and octal number method.

Option: (1) Symbol method:

Command format: chmod {u|g|o|a}{+|-|=}{r|w|x} filename

U (user) indicates the users themselves.

G (group) represents the same group of users.

O (oher) represents another user.

A (all) represents all users.

+ Used to give permission to the specified user.

-Used to cancel the permissions of the specified user.

= Assign the permission to the file.

R (Read) Read permission, which means that the contents of the file or directory can be copied.

W (write) writes a permission that indicates that the contents of the file or directory can be modified.

X (execute) Executes the license, indicating that the file can be executed or entered into the directory.



(2) Octal number method:

Command format: chmod ABC file

Each of the a,b,c is an octal number, which represents the permissions of user, Group, and other respectively.

4 (100) indicates readable.

2 (010) indicates writable.

1 (001) indicates executable.

To rwx the attribute then 4+2+1=7;

To rw-the attribute then 4+2=6;

To r-x the property, 4+1=5.



Example: # chmod A+RX filename

Allows all users to read and execute file filename.

# chmod GO-RX filename

Cancels the permissions of the same group and other users to read and execute file filename.

# chmod 741 filename

Allow me to read and write execution, the same group of user-readable, other user executable file filename.

# Chmod-r 755/home/oracle

Recursive change of directory permissions, I can read and write execution, the same group of user-readable executable, other user-readable executable



3. Modify File Date

Command: Touch

Format: Touch Filenae

Function: Change the date of the file, do not modify the contents of the file, if the file does not exist, create a new file.

For example:% Touch file



4. Link files

Command: ln (link)

Format: ln [option] filename linkname

ln [option] Directory pathname

Function: Create a chain for a file or directory. where filename and directory are the source file names and

The source directory name, Linkname, and pathname, respectively, that are linked to the source file or source directory name.

File or directory.

Option:-S to create a symbolic link for a file or directory. Do not add-s to create a hard link for a file or directory

Note: The purpose of a link is to give more than two names to a file or directory so that it can be

Now, in different directories, you can share files or directories and save disk space.

For example:% ln-s filename linkname



5. Display Date

Command: Date

For example:% date



6. Show Calendar

Command: Cal (Calendar)

Format: Cal [month] Year

Function: Displays the calendar specified within a year

Example:% cal 1998



7. Display the file header

Command: Head

Format: head [option] filename

Function: Display the file's head

Option: The first 10 rows of the file are displayed by default.

-I displays the start of the file I line.

Example:% head filename



8. Display the tail of the file

Command: Tail

Format: tail [option] filename

Function: Displays the tail of the file

Option: Displays the last 10 lines of the file by default.

-I displays the last line of the file.

The +i is displayed starting at line I of the file.

Example:% tail filename



9. Display User ID

Command: ID

Format: ID [option] [user]

Features: Displays the user ID and all groups to which the user belongs.

Option:-a displays the user name, user ID, and all groups to which the user belongs

Comments:

Example:% ID username



10. View the currently logged on user

Command: Users



11. Show who is logged on to the machine

Command: WHO

Format: Who

Function: Displays all user names currently in the system, using terminal number, registration time.

For example:% who



12. Display the user name on the current terminal

Command: WhoAmI

Format: WhoAmI

Function: Displays the user used on the current terminal.

Example:% WhoAmI



13. Finding files

Command: Find

Format: Find pathname [option] Expression

Function: Look for a file that matches the expression in the given path name.

Option:-name indicates file name

-user user name, select the file to which the user belongs

-size by size, in block, a block is 512B

-mtime n Search by last modification time, select files modified in n days

-perm Search by permissions

-type Find by File type

-atime Search by last access time



For example:% find./-name ' *abc* '-print



14. Search for matching characters in files

Command: grep

Format: grep [option] pattern filenames

Function: Searches the specified file or standard input line by row, and displays each row of the matching pattern.

Option:-I ignores case when matching

-V Find the row for pattern mismatch



For example:% grep-i ' java* './test/run.sh



15. Statistical file Count

Command: WC [option] filename

Features: Number of file lines, words, and characters in the statistics file.

Options:-L Statistics File line count

-W Statistics file number of words

The number of characters of the-C statistic file

Note: If the default file name refers to the standard input

For example:% wc-c./test/run.sh



16. Show Disk space

Command: DF (disk free)

Format: DF [option]

Function: Displays disk space usage, including file system installation directory name, block device name, total

The number of bytes, bytes used, and percentage of bytes remaining.

Options:

-A: Displays all file systems and disk usage for each partition

-I: Show i-nodes usage

-K: size is represented by K (default value)

-T: Displays all partition disk usage for one file system

-X: Displays all partition disk usage that are not a single file system

-T: Displays the name of the file system to which each partition belongs

-H: Indicates the use of "human-readable" output, that is, in the file system size using GB, MB and other easy-to-read format.

Comments:

Example:% Df-hi



17. Query the disk usage space of the file or directory

Command: Du (disk usage)

Format: du [option] [filename]

Function: Displays the amount of disk space occupied by all the files in each directory in a subdirectory of the specified directory

Options:

-A: Displays the disk space occupied by all directories and each file under the second directory

-B: Size is represented by bytes (default is k bytes)

-C: Last plus Total (default value)

-S: Show only the sum of each file size

-X: Only files that belong to the same file system are counted

-L: Calculate all file sizes

-H: Indicates that the file system size is in an easy-to-read format such as GB and MB.

Example:% du-a

% du-sh/etc only shows the sum of this directory

% Du/etc | Sort-nr | More statistical results are sorted using the sort command,

The parameter-nr of sort indicates that you want to reverse-sort by a numeric sort.



18. Show Process

Command: PS

Format: PS [option]

Features: Displays information about processes in the system. Includes process ID, control process terminal, execution time, and command.

Options:

-a displays all process information

-U uidlist Lists all processes for this user

-e Displays each process information that is currently running

-F Displays a complete list

The-x display includes process status without terminal control.

Comments:

Example:% Ps-ef

% Ps-aux then use a pipe symbol to guide grep to find a specific process and then manipulate the specific process.



19. Terminating the process

Command: Kill

Format: Kill [option] PID

Function: Sends a signal to the specified process or terminates the process. The KILL command is used to send a signal to a process,

Because most of the SIGKILL or SIGHUP are sent to kill the process, so called kill

Options:-9 forcibly terminate the process

Note: PID indicates the process number, which can be obtained by the PS command.

Example:% kill-9 pid

You can also use Kill-l to see the number of words that can be substituted for signal numbers. For more information on kill, see Man Kill.



20. View your IP address

Command: Ifconfig

Format: ifconfig-a



21. View the routing table

Command: Netstat

Format: Netstat-rn



22. Telnet

Command: Telnet

Format: telnet hostname



23. File Transfer

Command: FTP (file transfer program)

Format: FTP hostname

Functions: Network File transfer and remote operation.

Options: FTP command:

CD [dirname] into the remote machine directory

LCD [dirname] set directory for local machine

Dir/ls displaying remote directory files

Bin is transferred in binary mode

ASC is transmitted as a text file

Get/mget fetching one or more files from a remote machine

Put/mput sending one or more files to the remote machine

Prompt interactive hints When multiple file transfers are turned on or off

Close closes the connection to the remote machine

Quit FTP

!/exit FTP login state,! Indicates that the FTP state is temporarily exited back to the local directory, exit indicates the FTP state is returned

Comments:

For example:% FTP hostname



24. View your Email

Command: MAILX

Format: MAILX

Options:

Delete Deletes

Next

Quit quitting

Reply reply



25. Recall command

Command: History

Format: History

Features: Helps users recall executed commands.

Options:

Comments:

For example:% history



26. Online dialogue

Command: Talk

Format: Talk username

Function: Chat with another user on the web.

Options:

Note: The system divides the terminal into two parts in the dialogue, the upper part displays its own type of information, the second part

Displays information typed by the other user. Type Delete or CTRL + C to end the conversation.

For example:% talk username



27. Allow or refuse to accept information

Command: MESG (message)

Format: MESG [n/y]

Functionality: Allows or denies other users from sending information to the terminal they are using.

Option: N denies other users from writing to the terminal they are using

Y allows other users to write information to the terminal they are using (default value)

Comments:

Example:% MESG N



28. Write messages to other users

Command: Write

Format: Write username [ttyname]

Function: Write information to other users ' terminals.

Options:

Note: If the other party does not reject, two users can chat, type EOF or CTRL + C to end the conversation.

Example: Write username



29. Create, modify, delete users and groups

A. Create a group:

Example: Groupadd oinstall create groups named Oinstall

Groupadd-g 344 dba

Create a group with a group number of 344, at which time a group ID (GID) is generated in the/etc/passwd file as a 344 project.

B. Modify the group:

Groupmod: This command is used to change the properties of the user group account

Groupmod–g new GID user group account name

Groupmod–n New group name original group name: This command changes the name of the user group



C. Delete a group:

Groupdel Group Name: This command is used to delete the specified group account number



D. Create a new User:

Command: Useradd [-D home] [-s Shell] [-c comment] [-M [--template]]

[-F Inactive] [-e Expire] [-P passwd] [-R] Name

Main parameters

-C: Add note text, note text is saved in passwd's remarks column.

-D: Specifies the start directory at which the user logged in.

-D: Change the preset value.

-e: Specifies the expiration date of the account and the default is permanent.

-F: Specify the number of days after the password expires to close the account.

-G: Specifies the group to which the user belongs.

-G: Specifies the additional group to which the user belongs.

-M: Automatically establish the user's login directory.

-M: Do not automatically create a user's login directory.

-N: Cancels the creation of a group named after the user name.

-R: Set up the system account.

-S: Specifies the shell to use when the user is logged in.

-U: Specifies the user ID number.



Example: # useradd-g oinstall-g DBA Oracle Create Oracle User



E. Deleting users

Command: Userdel user name

Delete the specified user account

Userdel–r User name (userdel user name; RM username): Delete the specified user account and host directory

Example: #useradd-G root KKK//Add KKK user to the root group



F. Modifying users

Command: Usermod

Modify information for an existing user

Usermod–l old username New user name: Modify user Name

USERMOD–L user name: Used to lock the specified user account so that it cannot log on to the system

Usermod–u Username: Unlocking a locked user account

Passwd–d Username: Make the Account no password, that is, the user does not need a password to log on to the system

Example: #usermod-L User2 user1//renaming user User2 to User1



30. Start and close the firewall

Open permanently or close

Chkconfig iptables on

Chkconfig iptables off

Immediate effect: Restore after reboot

Service Iptables Start

Service Iptables Stop

Or:

/etc/init.d/iptables start

/etc/init.d/iptables stop



31. Start the VSFTP service

Instant Start:/ETC/INIT.D/VSFTPD start

Instant STOP:/ETC/INIT.D/VSFTPD stop



Boot default vsftp service starts automatically:

Method one: (Common \ Convenient)

[Email protected] etc]# chkconfig--list|grep vsftpd (view)

VSFTPD 0:off 1:off 2:off 3:off 4:off 5:off 6:off

[[email protected] etc]# chkconfig vsftpd on (performing on setting)

Or: Method Two:

Modify the file/etc/rc.local, put the line/USR/LOCAL/SBIN/VSFTPD & Insert the file in order to enable the boot automatically.



VI Tips

A. Enter input mode

New (Append)

A: From the cursor position to start the new data, the data after the cursor with the new data to move forward.

A: Start adding data from the end of the column where the cursor is located.



Inserting (insert)

I: Insert data from the cursor position, and the data after the cursor moves with the new data.

I: Insert data from the first non-whitespace character in the column where the cursor is located.



Start (Open)

O: Add a new column under the Cursor column and enter the input mode.

O: Add a column above the cursor column and enter the input mode.

B. Exit VI

In instruction mode type: Q,:Q!,:WQ or: X (note: number), you will exit VI. Where: Wq and: X is to save the exit, and: Q is directly exited, if the file has new changes, VI will
Prompts you to save the file and: The Q command also fails, you can use: w command to save the file and then use: Q
Exit, or use: Wq or: X command to exit, if you do not want to save the changed file, you need to use: q! command, this command will not save the file and directly exit VI.




C. Delete and modify a file command:

x: Deletes the character of the cursor.

DD: Deletes the column where the cursor is located.

R: Modifies the character of the cursor, and R is followed by the characters to be corrected.

R: Enter the replace state and the new text will overwrite the original text until you press [ESC] back to instruction mode.

S: Delete the character of the cursor and enter the input mode.

S: Delete the column where the cursor is located and enter the input mode.



D. Screen Tumbling Class command

Ctrl+u: First half screen to file

Ctrl+d: Half-screen to the end of the file

CTRL+F: Flip a screen to the end of a file

Ctrl+b: Turn one screen at the top of the file

NZ: Rolls line N to the top of the screen and scrolls the current line to the top of the screen when n is not specified.



E. Delete command

NDW or NDW: Delete the n-1 characters at the beginning and after the cursor

Do: Delete to the beginning of the line

d$: Delete to end of line

NDD: Deletes the current line and its subsequent n-1 rows

X or x: Deletes a character, x deletes the cursor, and x deletes the cursor before the

Ctrl+u: Delete text entered under input mode



F. Search and Replace commands

/pattern: Searches for pattern at the end of the file from the beginning of the cursor

? pattern: Searches for pattern from the beginning of the cursor to the top of the file

N: Repeat the last search command in the same direction

N: Repeats the last search command in the opposite direction

: s/p1/p2/g: Replaces all P1 in the current row with P2

: n1,n2s/p1/p2/g: All P1 in line N1 to N2 are replaced with P2

: g/p1/s//p2/g: Replace all P1 in the file with P2



G. Copying, pasting

(1) Select text block, use V to enter visual mode; Move cursor key selection

(2) Copy the selected block to the buffer, use Y; Copy the whole line, with YY

(3) Cut the selected block to the buffer, use D; cut the whole line with DD

(4) Paste the contents of the buffer, using p



H. Other

Open the second file in the same edit window with: SP [filename]

Switch between multiple edit files, using Ctrl+w

How Linux views common commands such as process, kill process, start process, etc.