Command line Basics

Catalog

One 、 Redirect

1、 function

2、 Format

3、 example

Two 、 Pipeline operation

1、 function

2、 Format

3、 example

3、 ... and 、find command

1、 function

2、 Format

3、 Options

4、 example

Four 、grep command

1、 function

2、 Format

3、 Common command options

4、 Common regular expressions

5、 example

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One 、 Redirect

1、 function

Redirect Save the screen display information to a file

2、 Format

Output override redirection display information > file

Output additional redirection display information >> file

Output force override redirection display information >| file

Input redirection command < file

3、 example

[[email protected] ~]# hostname > /home/wangwu/hostname.txt

[[email protected] ~]# cat /home/wangwu/hostname.txt

localhost

[[email protected] ~]# hostname >> /home/wangwu/hostname.txt

[[email protected] ~]# cat /home/wangwu/hostname.txt

localhost

localhost

[[email protected] ~]# hostname >| /home/wangwu/hostname.txt

[[email protected] ~]# cat /home/wangwu/hostname.txt

localhost

[[email protected] ~]# cat < /home/wangwu/hostname.txt

localhost

Two 、 Pipeline operation

1、 function

Pipeline command Use | Leave the standard output of the previous command to the next

2、 Format

command | command | ...

3、 example

[[email protected] ~]# ifconfig | head -1

ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500

3、 ... and 、find command

1、 function

find command Recursively find the corresponding condition according to the preset condition

2、 Format

find Catalog Conditions

find [ Catalog ] [ Conditions ]  -exec Processing command   Search results \;

Find by criteria , And deal with the results

3、 Options

Common condition expression

-type type （f、d、l）

-name“ Document name ”

-size +|- file size （k、M、G）

-user user name

-mtime Modification time

4、 example

[[email protected] ~]# find /etc/ -name passwd

/etc/passwd

[[email protected] ~]# find /boot/ -size +50M -exec ls -lh {} \;

-rw-------. 1 root root 71M Dec  4 15:22 /boot/initramfs-0-rescue-dbe7b11ce791478cbe8b60d8ffa6de6b.img

Four 、grep command

1、 function

grep command For searching text content , Sure Use Regular expressions , Or from Extract text lines according to string format

2、 Format

grep  [ Options ] ‘ Regular expressions ’ text file

3、 Common command options

-v Reverse match

-i Ignore case

-c Only the matching line numbers are output

-h Do not display the file name when querying the file

-l When querying a file, only the file name containing matching characters is output

-n Show matching line numbers

-s Do not display error messages

4、 Common regular expressions

Wang Include string Wang

^Wang In string Wang start

Wang$ In string Wang ending

Wan.  Wan+ Match a single character

W*  W+ Any number of characters

5、 example

[[email protected] wangwu]# cat wangwu.txt

Wang

Wang wu

Da Wang

Wang1

wang

[[email protected] wangwu]# grep Wang wangwu.txt

Wang

Wang wu

Da Wang

Wang1

[[email protected] wangwu]# grep ^Wang wangwu.txt

Wang

Wang wu

Wang1

[[email protected] wangwu]# grep Wang$ wangwu.txt

Wang

Da Wang

[[email protected] wangwu]# grep Wan. wangwu.txt

Wang

Wang wu

Da Wang

Wang1

[[email protected] wangwu]# grep W* wangwu.txt

Wang

Wang wu

Da Wang

Wang1