Linux command
1. Simple system command
# View ip address ip a ip addr # ping network (test network connectivity) ip Of the target machine ip # View system time date # cancellation logout # Shut down shutdown now # restart reboot # Clear screen clear
2.Linux file system
Linux | meaning | Windows |
---|---|---|
/bin | Storage location of basic commands available to all users | There is no fixed command storage directory |
/sbin | Administrator privileges are required to all commands | |
/boot | Files that need to be loaded and used when the linux system starts | |
/dev | After the peripheral is connected to linux, the corresponding file storage location | It is similar to the symbol file of U SB flash disk and Cd in Windows. |
/etc | After the peripheral is connected to linux, the corresponding file storage location | Similar to the registry in windows, |
/home | Home directory. Every new user in linux will be automatically assigned a folder in home | Similar to "My Documents" in windows, each user has its own directory. |
/root | The home directory of the root account, which is only used by the root account | Similar to "My Documents" of Administrator account in windows |
/lib | linux commands and system startup need to use some public dependencies, which are placed in lib, similar to the jdk jar s that we need to introduce for code execution | |
/usr | Default installation path of many system software | It is similar to the Program Files directory under the C disk in windows. |
/var | Log files and cache files generated by system and program operation are placed here |
3. Document management order
Note: commands are case sensitive
# View the list of files in the current directory ls # View the files in the specified directory ls / # View details, metadata information (user, group, size, creation time, permission information, file type) ls -l # view hidden files ls -a # Parameter combination ls -la # 2. Switch directories cd Destination folder # Absolute path switching cd Absolute path # Absolute path switching cd Relative path # Example: switch to /etc/sysconfig/networks-scripts directory # pwd view the directory where the current command is located # Special catalog symbols ~ Current user's home catalogue . current directory .. Upper level directory # 4. Create new folders and files # Create a new folder in the current location mkdir Folder name # In the specified directory location, create a folder and create a parent folder mkdir -p /a/b/Folder name # Create a new file in the current directory touch file name # 5. Delete file # Delete file rm file # remove folders rm -r folder # Force deletion without asking rm -rf file # 6. Copy files # Copy files cp Original document new document # Copy folder cp -r Source folder new folder # 7. Move the file or modify the file name # Move source files to destination folder mv File folder # Change the name of document A to document B mv file A file B # 8. Obtain md5 fingerprint (digital signature) of the file md5sum file name # brief introduction 1. Digital signature, also known as digital fingerprint 2. You can verify whether the file has been modified 3. A string of strings calculated from a file,Unique mark of file content(The contents of the document remain unchanged,Fingerprints will not change)
4. Text content viewing command
cat command
# View all the information in the file (suitable for viewing small documents) cat file name cat -n test.log |grep "debug" Query keyword logs # Select the middle row of keywords Then check the logs of the first 10 rows and the last 10 rows of this keyword: tail -n +92 means to query the logs after 92 rows cat -n test.log |tail -n +92|head -n 20
less command
# Browse the file information in paging mode (suitable for viewing large documents), and enter the browsing mode less file name # Browse mode shortcut ↑ #previous line ↓ #next row G #last page g #first page Space #next page /key word #Search keywords # Exit browse mode and return to Linux command line mode q #sign out
tail command
# Scroll the last 10 lines of information of the file in real time (default 10 lines) tail -f file name # Display the last 20 lines of information in the file tail -n 20 file name tail -n -20 file name # Display file information from line 20 to the end of the file tail -n +20 file name
/** Parameter explanation: -f This parameter is used for monitoring File File growth. -c Number from Number Read the specified file at byte position -n Number from Number Read the specified file at the line position. -m Number from Number Read the specified file at the position of multi byte characters. For example, if your file includes Chinese characters, assume that it is specified-c Parameter, which may cause truncation, but use-m This problem will be avoided. -b Number from Number Read the specified file at the 512 byte block position represented by. -k Number from Number Indicated 1 KB The block position reads the specified file.
head command
Contrary to the tail command
# Query the first 10 lines of logs in the log file; head -n 10 test.log # Query all logs except the last 10 lines of the log file; head -n -10 test.log
sed command
# Query the log according to the date. First, grep'2014-12-17 16:17:20 'test Log to determine whether there is this time point in the log sed -n '/2014-12-17 16:17:20/,/2014-12-17 16:17:36/p' test.log # Delete rows that include keywords sed -i '/key word/d' main.log
Using the more and less commands
# In this way, you can print pages by clicking the space bar cat -n test.log |grep "debug" |more
>xxx
# Use >xxx Txt save it to a file, and then you can pull down the file for analysis cat -n test.log |grep "debug" >debug.txt
split command
The log file is too large, which can be viewed after cutting
#1 cut according to the number of rows split -l 50000 main.log newfile_ --verbose #2. Cut according to byte size: [split by 40mb per file] split -b 40m main.log -d newfile_ --verbose
grep command
# Print 5 lines before and after the matching line grep -5 'parttern' inputfile # Print 5 lines before and after the matching line grep -C 5 'parttern' inputfile # Print the last 5 lines of the matching line grep -A 5 'parttern' inputfile # Print the first 5 lines of the matching line grep -B 5 'parttern' inputfile
/** -i:Ignore case when searching -c:Output only the number of matching rows -l:Only the matching file names are listed, and the specific matching lines are not listed -n:List all matching lines and display line numbers -h:Do not display file names when querying multiple files -s:Do not display error messages that do not exist or have no matching text -v:Show all lines without matching text -w:Match whole words -x:Match entire row -r:Recursively searching -q:It is forbidden to output any results. The exited status indicates whether the search is successful -b:Print the offset of the matching line spacing file header, in bytes -o:And-b Used in combination, print the offset of the head of the matched word data file, in bytes
5. File search
File name lookup
# grammar find Search path -name "File name keyword" # example find / -name "passwd" find / -name "ifcfg-*"
File content search
# grammar grep -Parameter the directory range to find # parameter -n Display the line number of the search result -R Recursively find all files in the directory # example grep aries /etc grep aries /etc/passwd
6. System management
# Statically view system processes # Statically view system processes ps -ef Displayed results: 1.UID user ID 2.PID process ID 3.PPID Parent process ID 4.C CPU Occupancy rate 5.STIME start time 6.TTY To start this process TTY----terminal equipment 7.TIME Total time this process has been running 8.CMD Command name # View the system process in real time top # Shortcut key ↑ Turn down ↓ Upturn q sign out # Close process kill process id # Force the process to close (use with caution) kill -9 process id
Force process shutdown psmisc tool
# Display the current process of the system in the form of tree pstree # Kill process killall Process name # Show which process is using this file fuser /Target file
7. Output
Overwrite output
# Output the execution result of command 1 to the following file. `Overwrite write` Command 1 > file # example date > date.log
Append output
# Output the execution result of command 1 to the following file. `Append write` Command 1 >> file # example date >> date.log
8. Pipeline
# Syntax, take the output result of command 1 as the input of Command 2 Command 1 | Command 2
# example lookup aries User: cat /etc/passwd | grep -n "baizhi" lookup aries Group: cat /etc/group | grep -n "baizhi" lookup sshd Process: ps -aux | grep sshd Find logs tail log file | grep "keyword" Paging lookup log less log file | grep "keyword" Find the entire log more log file | grep "keyword" Find groups in the system cat File of system group | grep "keyword"
9. Document editing
System permissions | user groups
1. Create group `groupadd Group name` 2. delete group `groupdel Group name` 3. Find groups in the system `cat /etc/group | grep -n "Group name "` Note: each group information of the system will be stored in/etc/group In the file of
user
1. Create user `useradd -g Group name user name` 2. Set password `passwd user name` 3. Find system account Note: each user information of the system is saved in`/etc/passwd`In the document 4. Switch users `su user name` 5. delete user `userdel -r user name`
Permission setting
Syntax: chmod u±rwx,g±rwx,o±rwx file name Operator: - Delete permissions + add permission = Assignment authority ## Add execution permission to the owner of the file chmod u+x file name ## Delete all permissions to others in the file chmod o-rwx file name ## Set read and write permissions for the group to which the file belongs chmod g=wx file name -------------------------2----------------------------------------- # The authority value of each owner of the file is calculated by using the sum of rwx. # grammar `chmod [-R] nnn file` -R Recursively set all files in the folder # Set the permissions of the file to (the owner is readable, writable and executable, the group is readable and writable, and others are readable) chmod 764 file name
10. Compression and decompression
parameter | describe |
---|---|
-z | To operate the tar.gz file, you need to use |
-x | decompression |
-c | Compress the specified storage location |
-v | Display the execution process information of compression or decompression |
-f | The file to be processed must be placed at the end |
.zip format decompression and compression
# Install zip software first yum install zip # Installation without confirmation yum install -y zip Uninstall: yum remove zip Compressed file name original file # Compressed file zip -r Compressed file name original file # Compressed file zip Compressed file name original file zip a.zip a.txt # Recursive if folder [if recursive compression is not specified, just compress the folder] zip -r Compressed file name original folder zip -r bb.zip bb unzip Compressed file #Extract the.zip file unzip Compressed file name ;decompression
.gz format decompression and compression
# Install the file in.gz format first gzip Original document #Compressed to.gz format, the original file will disappear gzip -c Original file compressed file #Compress to.gz format, and keep the original file #-c does not mean that you need to keep files, but to output the compressed results to the console #>It means where to output the results gzip -r catalogue #Compress all sub files under the directory, but you cannot compress the directory gzip Original document : Compress the file, and the source file will disappear gzip a.txt gzip -r Original folder : Traverse the folder, compress the files in the folder, and the directory is not compressed gzip -d Compressed file gunzip Compressed file #Unzip file directory gunzip -r Compressed file directory ;decompression #Unzip file gunzip Compressed file
.bz2 format decompression and compression
bzip2 source file #Compressed to.bz2 format, the source file cannot be retained bzip2 -k source file #Keep source files after compression be careful:bzip2 The command cannot compress directories bzip2 -d source file #decompression bunzip2 Compressed file #Decompress, -k keep the compressed file bunzip2 -k Compressed file
.tar.gz format
# Packaging Command & unpacking Packaging command: tar -cvf Package file name source file option: -c pack -v Display process -f Specify the packed file name tar -cvf learn.tar learn Unpacking command: tar -xvf Package file name option: -x Unpacking
Compression and decompression
# compress tar -zcvf Compressed package name.tar.gz source file option: -z Compress to.tar.gz format tar -zcvf learn.tar.gz learn #decompression tar -zxvf Compressed package name.tar.gz option: -x decompression .tar.gz format #Add -C to extract to the specified directory tar -zxvf Compressed package name.tar.gz -C Specify directory decompression: tar -zxvf learn.tar.gz -C catalogue compress: tar -zcvf learn.tar.gz learn
rmp software
1. install rpm Software Syntax:`rpm -ivh xxx.rpm` 2. Check whether this has been installed in the system rpm Software Syntax:`rpm -qa Software name` 3. uninstall rpm Software Syntax:`rpm -e Software name` 4. Example: installation tree tool Function: view the file information in a directory # View level 2 file information in a tree structure tree -L 2 Path to view
yum command
yum is implemented based on rpm. In addition to the functions of installing and uninstalling software of rpm, it also automatically finds and downloads software, automatically handles the dependencies between software, and downloads and installs dependent packages
## List all packages that can be installed yum list ## Install software yum install -y Software name ## Uninstall software yum remove Software name ## Find packages yum search all Software name
11.linux services
# For example: sshd network firewalld, etc # Server management commands systemctl status service name # Start service systemctl start service name # Restart service systemctl restart service name # Out of Service systemctl stop service name # Prohibit the service from starting with linux. systemctl disable service name # The setup service starts with linux. systemctl enable service name
ip
[root@centos7 dirnew]# vim /etc/sysconfig/network-scripts/ifcfg-ens33 ----------------File content corresponding to the network card--------------------- TYPE="Ethernet" PROXY_METHOD="none" BROWSER_ONLY="no" BOOTPROTO="none" DEFROUTE="yes" IPV4_FAILURE_FATAL="no" IPV6INIT="yes" IPV6_AUTOCONF="yes" IPV6_DEFROUTE="yes" IPV6_FAILURE_FATAL="no" IPV6_ADDR_GEN_MODE="stable-privacy" NAME="ens33" UUID="0bd5d8a5-fe1b-42de-82bd-bfa7d2984b95" DEVICE="ens33" ONBOOT="yes" IPADDR="192.168.199.8" # Just modify the ip address here PREFIX="24" GATEWAY="192.168.199.2" DNS1="192.168.199.2" DNS2="8.8.8.8" IPV6_PRIVACY="no" [root@centos7 dirnew]# systemctl restart network #Restart network card service
firewall
# Turn on the firewall systemctl stop service name # Temporarily turn off the firewall systemctl stop firewalld # Disable firewall startup systemctl disable firewalld firewalld It is a service name or a port
# View hostname hostname # Set hostname hostnamectl set-hostname host name