See what types of shell interpreters are available on this machine:
[root@sanchuang huahsan]# cat /etc/shells /bin/sh /bin/bash /usr/bin/sh /usr/bin/bash /usr/bin/tmux /bin/tmux sh It's a very old interpreter, more than bash Have a sense of history, No bash Easy to use [root@sc ~]# sh switch to sh interpreter sh-4.4# Switch bash to bash interpreter [root@sc ~]#
Switching between sh and bash
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ls view the contents of the folder
-l display details
-a display all files and folders, including hidden files And
-A displays all files and folders, including hidden files, not displayed And
-h is displayed in units that can be recognized by human -- "K,M,G,T,P"
-h, --human-readable
with -l and -s, print sizes like 1K 234M 2G etc.
-t sort according to the creation time of the file. The last created file is in the front time
The default is the ASCII code value of the first letter of the file name, which is arranged in ascending order
-r according to the ASCII code value of the initial letter of the file name, it is arranged in descending order -- reverse
-d displays the attributes of the directory itself, not the attribute directory of the folder or file inside
-
[root@sc wuxia]# mkdir .song hides files or folders in linux to start [root@sc wuxia]# ll Total consumption 16 -rw-r--r--. 1 root root 144 10 September 13:54 create_dir.sh -rw-r--r--. 1 root root 103 10 October 13:04 create_user.sh -rw-r--r--. 1 root root 75 10 October 13:00 del_dir.sh drwxr-xr-x. 32 root root 4096 10 October 13:00 huashan d The type of representative file is directory (folder) directory - The type of representative file is ordinary file rwxr-xr-x Delegate authority r read read w write write x Execute (run) execute 32 Number of links to the file-->How many files in the folder are related to it root 1st root Representative is root user root 2nd root Representative is root group 4096 File size bytes Byte runout bytedance -->Company name -->Product tiktok today's headlines, watermelon videos, etc. Tik Tok byte byte -->B -->1 English letters are stored in the unit where the computer consumes 1 byte and 1 Chinese character consumes 3 bytes to store data 1kB = 1024B 1MB =1024KB 1GB=1024MB 1TB=1024GB 1PB=1024TB 1EB=1024PB k-->M-->G-->T-->P-->E 10 October 13:00 Creation time of the file
ASCII (American Standard Code for information interchange) is a set of computer coding system based on Latin alphabet, which is mainly used to display modern English and other Western European languages.
/Device stores device files device mouse, keyboard, display, disk, network card and other hardware will have a file corresponding to it – "everything in linux is a file"
brw-rw----. 1 root disk 8, 1 October 11 09:21 sda1 - "disk device file -" disk data storage related device file block block
crw–w----. 1 root TTY 4, 0 October 11 09:21 tty0 -- "character display file character character character
lrwxrwxrwx. 1 root 15 October 11 09:21 stderr - > / proc / self / FD / 2 -- "link file: shortcut link
===
What are the file types?
d folder (directory)
-Ordinary documents
l link file link
c character device file character
b device file block
===
[root@sc wuxia]# mkdir hunan
[root@sc wuxia]# Ln - s ABCD create a symbolic link to ABCD
source file Link file
-s symbol Symbol
Symbolic link=windows Shortcut in
Symbolic link=Soft link
[root@sc wuxia]# ll xiang
lrwxrwxrwx. 1 root root 5 10 November 13:18 xiang -> hunan
[root@sc wuxia]#
[root@sc wuxia]# cd xiang/
[root@sc xiang]# pwd
/wuxia/xiang
[root@sc xiang]# pwd -P
/wuxia/hunan
[root@sc xiang]#
-P, --physical Show real physical path
avoid all symlinks
===== practice: 1.new directory/10-13 folder 2.get into/10-13 Folder, create a new folder in it hunan hubei .shenzheng 3.Displays the details of the files in the current folder, including hidden files, but not displayed.and.. 4.Displays the size of the folder in units that humans can recognize 5.Displays the files in the current folder in descending order 6.stay hunan New folder under directory changsha yueyang zhuzhou 7.display hunan The detailed information of the directory itself is not displayed 8.to hubei Create a symbolic link file called e [root@sc 10-13]# ln -s hubei e 9.get into e Folder, display the current path (to display the real physical path) 10.use vim Editor in/10-13 Create a new file in the directory sc.txt ,Define the content 11.display/10-13 Details in folder =====
[root@sc 10-13]# mkdir -p hunan/{changsha,yueyang,zhuzhou}
-p If the file exists, no error will be reported
If the file does not exist, create a new one
[root@sc 10-13]# mkdir guangdong/{guangzhou/{baiyun,fanyu,huadu,tianhe},qingyuan,maoming,shaoguang,dongguang,zhuhai} -p
[root@sc 10-13]# mkdir hejin{1..10}
[root@sc 10-13]# rm -rf guangdong
rm Commands for deleting files and folders remove
rm - remove files or directories
-f, --force force
ignore nonexistent files and arguments, never prompt
-r, -R, --recursive recursion
remove directories and their contents recursively -->Zhulian nine Nationalities
-rf Forcibly delete all contents in folders and subfolders without giving any reminders
rm It is a dangerous command, because the deleted content will not enter the recycle bin. The system with the default character interface has no recycle bin
Reminder: when deleting things at work, ask yourself and leaders again and again if you still need them? Is there a backup?
Wildcard:
*Represents any character
? Represents an arbitrary character
[root@sc 10-13]# mkdir aa ab abc abd abcd abce
[root@sc 10-13]# ls
aa ab abc abcd abce abd e huangshan hubei hunan jiangxi jiujiang lushan sc.txt
[root@sc 10-13]# rm -rf a?
[root@sc 10-13]# ls
abc abcd abce abd e huangshan hubei hunan jiangxi jiujiang lushan sc.txt
[root@sc 10-13]# rm -rf a??
[root@sc 10-13]#
[root@sc 10-13]# touch feng{1..100}.txt new empty file
[root@sc 10-13]# rm -rf *.txt
[root@sc 10-13]# rm -rf feng??.txt
[root@sc 10-13]# rm -rf * deletes all files and folders in the current directory, but does not delete hidden files
Never use it or kill it
It will cause all files in the system to be deleted
[root@sc 10-13]# cd /
[root@sc /]# RM - RF * relative path
[root@sc /]# rm -rf / * absolute path
touch command
Purpose:
1.Create a new empty file. If the file does not exist, create a new one
2.Update file creation time
.txt yes windows Text file in -->There are text files, no pictures, no sound and video
[root@sc wuxia]# touch tang.txt
[root@sc wuxia]# ll tang.txt
-rw-r--r--. 1 root root 0 10 September 13-15:37 tang.txt
[root@sc wuxia]# date
2021 Wednesday, 13 October 2015:40:46 CST
[root@sc wuxia]# touch tang.txt
[root@sc wuxia]# ll tang.txt
-rw-r--r--. 1 root root 0 10 September 13-15:41 tang.txt
[root@sc wuxia]#
du is used to view the size of a file or folder
du - estimate file space usage -s Size after summary sum -h Display in a human recognizable format ,K M G -a Count the size of each file all [root@sc boot]# du -sh grub2 5.5M grub2 [root@sc boot]# [root@sc boot]# du -sh vmlinuz-4.18.0-193.el8.x86_64 8.6M vmlinuz-4.18.0-193.el8.x86_64 [root@sc boot]# [root@sc boot]# ls -l -h 134 total dosage M -rw-r--r--. 1 root root 184K 5 August 2020 config-4.18.0-193.el8.x86_64 drwxr-xr-x. 3 root root 4.0K 10 September 12:02 efi drwx------. 4 root root 4.0K 10 September 12:07 grub2 -rw-------. 1 root root 66M 10 September 12:06 initramfs-0-rescue-57d1329660644355897d0b9ff095549c.img -rw-------. 1 root root 29M 10 September 12:08 initramfs-4.18.0-193.el8.x86_64.img -rw-------. 1 root root 19M 10 September 14:40 initramfs-4.18.0-193.el8.x86_64kdump.img drwxr-xr-x. 3 root root 4.0K 10 September 12:04 loader drwx------. 2 root root 16K 10 September 12:01 lost+found -rw-------. 1 root root 3.8M 5 August 2020 System.map-4.18.0-193.el8.x86_64 -rwxr-xr-x. 1 root root 8.6M 10 September 12:05 vmlinuz-0-rescue-57d1329660644355897d0b9ff095549c -rwxr-xr-x. 1 root root 8.6M 5 August 2020 vmlinuz-4.18.0-193.el8.x86_64 [root@sc boot]# du -sh grub2/ 5.5M grub2/ [root@sc boot]# How to view the file size: 1.du -->recommend du -sh The size of the folder is counted 2.ll -h -->Cannot automatically count the size of the entire folder
cp copy files and folders
Operations on files
1.Copy a single file
2.Copy multiple files
[root@sc lianxi]# cp changsha.txt hunan
source file destination
[root@sc lianxi]# cp --help
Usage: cp [option]... [-T] Source file destination file
Or: cp [option]... source file... catalogue
Or: cp [option]... -t Directory source file...
[root@sc lianxi]# cp /etc/hosts /lianxi
[root@sc lianxi]# cp /etc/passwd . Copy the / etc / passwd file to the current directory, or is it called passwd
=====
[root@sc lianxi]# cp changsha. Txt sc.txt passwd Shanghai copy multiple files to a folder
The front is the source file Destination directory
[root@sc lianxi]# cp /etc/hosts /etc/passwd /lianxi/hunan
======
Copy, paste and rename in one step
[root@sc lianxi]# cp changsha.txt cs.txt will change Sha Copy and paste the txt file into the current directory and change its name to CS txt
Actions on folders
1.Copy a single folder
2.Copy multiple folders
3.-r Recursive copy, copy the sub files and sub folders in the folder
[root@sc lianxi]# cp -r hunan shanghai
[root@sc lianxi]#
[root@sc lianxi]# cp -r hunan shanghai
cp: Overwrite'shanghai/hunan/changsha.txt'？ y
cp: Overwrite'shanghai/hunan/hosts'？ y
cp: Overwrite'shanghai/hunan/passwd'？ y
[root@sc lianxi]# cp -r hunan shanghai
cp: Overwrite'shanghai/hunan/changsha.txt'？ y
cp: Overwrite'shanghai/hunan/hosts'？ y
cp: Overwrite'shanghai/hunan/passwd'？ y
cp: Overwrite'shanghai/hunan/feng1.txt'？ y
cp: Overwrite'shanghai/hunan/feng2.txt'？ y
cp: Overwrite'shanghai/hunan/feng3.txt'？ y
cp: Overwrite'shanghai/hunan/feng4.txt'？ y
cp: Overwrite'shanghai/hunan/feng5.txt'？ y
cp: Overwrite'shanghai/hunan/feng6.txt'？ ^C
[root@sc lianxi]# /usr/bin/cp -r hunan shanghai
[root@sc lianxi]# CP / boot / Lianxi - R use of absolute path
[root@sc lianxi]# cp /wuxia/ . -r mixed use of relative path and absolute path
[root@sc lianxi]# CP / Wuxia / / boot / etc / passwd / Lianxi / Hubei - R copy of multiple folders and files
[root@sc lianxi]# cp hunan xiang -r
Coverage issues
[root@sc lianxi]# cp changsha.txt hunan
cp: Overwrite'hunan/changsha.txt'？ y
[root@sc lianxi]#
Why cp Will the command give an override reminder?
[root@sc lianxi]# alias
alias cp='cp -i'
man cp Effect of
-i, --interactive interactive
prompt before overwrite Remind before overwriting
Solve the problem of reminder:
1.Cancel alias -->Not recommended
[root@sc lianxi]# unalias cp
2.use cp Absolute path of the command -->recommend
[root@sc lianxi]# /usr/bin/cp changsha.txt hunan
shell The interpreter is right linux When the command is interpreted, it is preferred to check whether there is an alias setting. If there is an alias, it is preferred to use the alias
[root@sc lianxi]# cp changsha.txt hunan
cp: Overwrite'hunan/changsha.txt'？ y
[root@sc lianxi]# which cp view the path where the cp command is stored
alias cp='cp -i'
/usr/bin/cp
[root@sc lianxi]#
file command view type
[root@sc lianxi]# file boot view the type of file boot: directory [root@sc lianxi]# file hosts hosts: ASCII text [root@sc lianxi]#
Exercise 3: 1.Create a new directory under the root directory wuxia 2.Then in wuxia New under directory tianshan,hengshan,taishan,songshan 3.stay tianshan Create a new empty file in the directory qijian，stay hengshan New directory empty file yilin，stay taishan New under directory xiaodeng 4.copy/etc/hosts reach songshan Directory, copy hengshan Directory to songshan Under the directory 5.see taishan File type, and then view taishan Size of directory 6.delete tianshan Directory, and then copy songshan Directory to taishan Directory called shaolin Exercise 4: 1.Create a new folder under the root directory jindafu 2.take/etc/hosts Copy files to jindafu 3.take/boot Copy directory to jindafu 4.take/etc/passwd Copy files to jindafu Lower boot In the catalogue 5.stay jindafu New in directory liufu Directory, and then jindafu Directory boot Copy directory to liufu Under the directory 6.delete liufu catalogue 7.copy/etc/hosts File to jindafu，Do not give coverage reminder? [root@sanchuang jindafu]# /usr/bin/cp /etc/hosts . 8.take/etc/hosts Copy files to jindafu Directory called huojianhua 9.take/home/Copy all files and folders in the directory to/jindafu Under the directory
Exercise 4:
1. Create a new folder under the root directory
2. Copy the / etc/hosts file to jindafu
3. Copy the / boot directory to jindafu
4. Copy the / etc/passwd file to the boot directory under jindafu
5. Create a liufu directory in the jindafu directory, and then copy the boot directory under the jindafu directory to the liufu directory
6. Delete liufu directory
7. Copy the / etc/hosts file to jindafu without giving overwrite reminder?
[root@sanchuang jindafu]# /usr/bin/cp /etc/hosts .
8. Copy the / etc/hosts file to the jindafu directory, which is called huojianhua
9. Copy all files and folders in / home / directory to / jindafu directory