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(6) VIM editor MV cat redirection standard input and output more pipe symbols head tail
2022-07-01 18:12:00 【Nan Yunxi】
One 、 Knowledge supplement
1.1 env
Check the current terminal shell Of environment variable ( Global variables )
Among the contents found HISTSIZT=1000, That is, the number of historical orders is 1000
1.2 vim Use of editor
Linux Text editor under ,vi Updated version of
【 install vim Editor 】yum install vim -y( The virtual machine must be able to access the Internet )
1.2.1 touch and vim The difference between creating files
touch a.txt Just create an empty file , Don't write content into the file
vim a.txt Not only create files , At the same time, you can write content into it . If a.txt The file already exists , Is the use of vim Open this file , If it does not exist, it is new
1.2.2 Operation steps
- Press i Enter input ( Insert ) Pattern
- Press Esc Key to return to command mode
- Input :wq( Must be in English input mode , A lowercase letter )==> Exit and save
- It can be done by cat Connect the file name to check the file content
[[email protected] lianxi]# vim lihua.txt
[[email protected] lianxi]# cat lihua.txt
lihua
Chian
hunan
Li Hua
China
Two 、 Command to explain
2.1 mv
1. Move (Move) File or directory ==> shear
[[email protected] lianxi]# ls
hua.txt hunan lihua
[[email protected] lianxi]# mv lihua hunan
[[email protected] lianxi]# ls
hua.txt hunan
[[email protected] lianxi]# ls hunan
lihua
You can move multiple folders at the same time , You can also move files and folders at the same time . here , The destination must be a folder , Otherwise, it cannot accommodate multiple contents
[[email protected] lianxi]# mkdir liming
[[email protected] lianxi]# touch lihua.txt
[[email protected] lianxi]# ls
hua.txt hunan lihua.txt liming
[[email protected] lianxi]# mv lihua.txt liming/ hunan
[[email protected] lianxi]# ls
hua.txt hunan
[[email protected] lianxi]# ls hunan
lihua lihua.txt liming
2. If the target location is the same as the original location or the target folder does not exist , Is quite renamed ==> rename
[[email protected] lianxi]# ls
hua.txt hunan
[[email protected] lianxi]# mv hunan xiang
[[email protected] lianxi]# ls
hua.txt xiang
2.2 cat
Show the full contents of the file
【 Options 】-n Number each line of output
[[email protected] lianxi]# file lihua.txt
lihua.txt: UTF-8 Unicode text
[[email protected] lianxi]# cat -n lihua.txt
1 lihua
2 Chian
3 hunan
4 Li Hua
5 China
2.2.1 cat Detailed functions
cat - concatenate files and print on the standard output
Connect files and output content to the screen
Connection file : At the same time, the contents of multiple files can be output at the same time , And connect them
[[email protected] lianxi]# cat lihua.txt
lihua
Chian
hunan
Li Hua
China
[[email protected] lianxi]# cat xiaoming.txt
Hello
xiaoming
[[email protected] lianxi]# cat lihua.txt xiaoming.txt
lihua
Chian
hunan
Li Hua
China
Hello
xiaoming
2.2.2 Redirect
Put the content that should be output on the screen , Redirect to a file , Changed his output direction
standard input Standard input ==》 keyboard
standard output Standard output ==》 The screen
Redirection actually changes the direction of output , The standard output is to output to the screen , Redirection can be output to a file
[[email protected] lianxi]# cat lihua.txt xiaoming.txt >lihua_xiaoming.txt
[[email protected] lianxi]# ls
hua.txt lihua.txt lihua_xiaoming.txt passwd xiang xiaoming.txt
[[email protected] lianxi]# cat lihua_xiaoming.txt
lihua
Chian
hunan
Li Hua
China
Hello
xiaoming
> Output redirection : If the following file does not exist, create , If it exists, the original content will be overwritten
[[email protected] lianxi]# echo hello,world >hello.txt
[[email protected] lianxi]# ls
hello.txt hua.txt lihua.txt lihua_xiaoming.txt passwd xiang xiaoming.txt
[[email protected] lianxi]# cat hello.txt
hello,world
[[email protected] lianxi]# echo HELLO,WORLD >hello.txt
[[email protected] lianxi]# cat hello.txt
HELLO,WORLD
>> Append output redirection : If the following file does not exist, create a new , If it exists, the original content will not be overwritten , Just append at the end
[[email protected] lianxi]# echo 123 >test.txt
[[email protected] lianxi]# cat test.txt
123
[[email protected] lianxi]# echo 456 >>test.txt
[[email protected] lianxi]# cat test.txt
123
456
2.2.3 tac
Read the contents of the file upside down
[[email protected] lianxi]# cat test.txt
123
456
[[email protected] lianxi]# tac test.txt
456
123
2.3 more
Full screen display of file content
Pagination display : Page by page display
2.3.1 Interactive operation method
- Press Enter Key down line by line
- Press the space bar to scroll down one screen , Press b Key up one screen
- Press q Key to exit
[[email protected] lianxi]# cp /var/log/messages .
[[email protected] lianxi]# more messages
2.3.2 | Pipe symbol
The function is to send the output of the previous command to the following command as input
Pipeline essentially realizes the communication between processes , It is a way of communication between processes
[[email protected] lianxi]# cat -n messages |more The line number is displayed , There is paging display
2.3.3 ps aux
see Linux Information about the current instantaneous process in the system
- USER Refers to which user started the process
- PID Is the number of the process process id
- %CPU Consumed by the process cpu Usage rate
- %MEM Memory consumed by the process memory
- COMMAND Is the name of the running process
[[email protected] lianxi]# ps aux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.0 0.6 128148 6756 ? Ss 2 month 14 0:05 /usr/lib/syst
root 2 0.0 0.0 0 0 ? S 2 month 14 0:00 [kthreadd]
root 4 0.0 0.0 0 0 ? S< 2 month 14 0:00 [kworker/0:0H
2.3.4 wc
Count the number of lines in a file 、 word 、 byte
- first 2 Express 2 That's ok
- the second 2 Express 2 Word
- 8 Represents eight bytes
A Chinese character occupies 3 Bytes , An English letter accounts for 1 Bytes , A space 、 A enter key takes up one byte
[[email protected] lianxi]# cat test.txt
123
456
[[email protected] lianxi]# wc test.txt
2 2 8 test.txt
[[email protected] lianxi]# cat test.txt |wc -l Statistics test.txt How many lines are there in the document
2
ps aux|wc -l Statistics ps aux How many lines of command output
ps aux|more Display process information in pages
【 Options 】
-l The statistical number of rows
-w Count the number of words
-c Count bytes
2.3.5 $()
effect : Give priority to the commands inside , Then return the execution result of the command
user_num=$(cat /etc/passwd |wc -l) Execute first cat /etc/passwd |wc -l Get the results , And then assign it to user_num This variable
[[email protected] lianxi]# cat /etc/passwd |wc -l
30
[[email protected] lianxi]# user_num=$(cat /etc/passwd |wc -l)
[[email protected] lianxi]# echo $user_num
30
2.3.6 less
And more The same command , But there are more extensions , The operation method is basically similar , There are some differences
【page down】 Page up 【page up】 Page down
【 differences 】more and less
- After the content is displayed ,less Do not exit ,more Will automatically exit
- less Can press 【page down】【page up】, and more no way
2.4 head
purpose : Look at the beginning of the file ( Default is header 10 That's ok )
Format :head -n numbuer file name
Format :head - Numbers file name
[[email protected] lianxi]# head -3 messages be equal to [[email protected] lianxi]# head -n 3 messages
[[email protected] lianxi]# cat -n messages |head -3
1 Feb 13 17:27:01 192 rsyslogd: [origin software="rsyslogd" swVersion="8.24.0-55.el7" x-pid="1069" x-info="http://www.rsyslog.com"] rsyslogd was HUPed
2 Feb 13 17:37:33 192 dhclient[864]: DHCPREQUEST on ens33 to 192.168.255.254 port 67 (xid=0x7c8e74b0)
3 Feb 13 17:37:33 192 dhclient[864]: DHCPACK from 192.168.255.254 (xid=0x7c8e74b0)
2.5 tail
purpose : Look at the end of the file ( The default is after 10 That's ok )
Format :tail -n numbuer file name
Format :tail - Numbers file name
2.5.1 tail Advanced usage of
tail -n +number Used before you don't want to display number The content of the line , Show from page number From the beginning to the end of the line
[[email protected] lianxi]# df -Th
file system type Capacity Already used You can use Already used % Mount point
devtmpfs devtmpfs 475M 0 475M 0% /dev
tmpfs tmpfs 487M 0 487M 0% /dev/shm
tmpfs tmpfs 487M 7.7M 479M 2% /run
tmpfs tmpfs 487M 0 487M 0% /sys/fs/cgroup
/dev/mapper/centos-root xfs 17G 1.6G 16G 10% /
/dev/sda1 xfs 1014M 138M 877M 14% /boot
tmpfs tmpfs 98M 0 98M 0% /run/user/0
[[email protected] lianxi]# df -Th|tail -n +2 From the second line to the end
devtmpfs devtmpfs 475M 0 475M 0% /dev
tmpfs tmpfs 487M 0 487M 0% /dev/shm
tmpfs tmpfs 487M 7.7M 479M 2% /run
tmpfs tmpfs 487M 0 487M 0% /sys/fs/cgroup
/dev/mapper/centos-root xfs 17G 1.6G 16G 10% /
/dev/sda1 xfs 1014M 138M 877M 14% /boot
tmpfs tmpfs 98M 0 98M 0% /run/user/0
tail -f test.txt Dynamic monitoring test.txt Changes in the contents of the document : Stare at the end of the file , Once there is input , Output to the user immediately
It is generally used when we look at the change of a log file
Press Ctrl + C force finish
[[email protected] lianxi]# tail -f test.txt
123
456
HELLO
TEST
( Copy label ) Use the redirection function in another terminal to add
[[email protected] ~]# cd lianxi
[[email protected] lianxi]# echo HELLO >>test.txt
[[email protected] lianxi]# echo TEST >>test.txt
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