Linux basic commands

1, Class notes:

  • su - meaning and home directory meaning?

When switching users, the configuration information of the user's home directory will be called / loaded. For example, if a command is configured for the user alone, only the user will recognize the command, and other users cannot.

  • Relative path and absolute path

Start with /, not with /

  • What is the difference between cd /home and cd /home /?

The difference is whether home is a directory or a file. The last / is the directory separator

  • Alias alias

    Enter alias on the command line to view all aliases in the system

    Note: the alias defined on the command line is only valid for the current shell process. If you want to be valid permanently, you should define it in the configuration file only for the current user: ~ / Bashrc is valid for all users: / etc/bashrc

  • File + file name / / you can view the file type

    Do not look at the extension under Linux,

2, View files more, less, cat, head, tail

  • Small files can be viewed with cat, and long files can be viewed with more and less, or head and tail

  • cat -n: displays the line number

  • tail -f /var/log/messages dynamic monitoring log files

  • more: used when browsing longer files

    Enter: next line

    Space: next page

    b: Previous page

    q: Exit

  • less: used when browsing long documents and turning pages up and down

    Up key: previous line

    Down key: next line

    pageup: Previous page

    pagedown: next page

    q: Exit

3, Create file touch

<span style="background-color:#282c34"><span style="color:#282c34"> <span style="color:#abb2bf">touch a.txt             </span>
 <span style="color:#abb2bf">touch a.txt b.txt</span>
 <span style="color:#Abb2bf "> touch a {1.. 6}. TXT / / use wildcard {}</span>
 <span style="color:#abb2bf">touch {a,b,c}{1..3}.txt</span>
 <span style="color:#abb2bf">a1.txt  a2.txt  a3.txt  b1.txt  b2.txt  b3.txt  c1.txt  c2.txt  c3.txt</span></span></span>

4, Create directory mkdir

<span style="background-color:#282c34"><span style="color:#282c34"> <span style="color:#abb2bf">mkdir aa</span>
 <span style="color:#Abb2bf "> MKDIR - P - v A / B / C / / - P recursively creates directories, - v displays the creation process</span>
 <span style="color:#abb2bf">mkdir abc{1..3}</span></span></span>

5, Delete rm

<span style="background-color:#282c34"><span style="color:#282c34"> <span style="color:#Abb2bf "> RM - R / / deleting directories also plays a recursive role</span>
 <span style="color:#Abb2bf "> RM - F / / delete files and force deletion</span>
 <span style="color:#Abb2bf "> RM - RF / / can be deleted</span></span></span>

6, Copy cp

<span style="background-color:#282c34"><span style="color:#282c34"> <span style="color:#abb2bf">touch a1 a2</span>
 <span style="color:#abb2bf">mkdir D1 D2</span>
 <span style="color:#Abb2bf "> CP - P A1 A2 / TMP / / keep the attributes and permissions of the original file</span>
 <span style="color:#Abb2bf "> CP - R D1 / TMP / D3 / / adding - r when copying a directory indicates recursive copying, otherwise an error will be reported</span>
 <span style="color:#abb2bf">[root@localhost opt]# cp /opt/D1/ /tmp/D3</span>
 <span style="color:#abb2bf">cp: omitting directory '/opt/D1/'</span></span></span>

7, Mobile mv

mv file1 /tmp/;ls /tmp/file //; Is a command separator that allows you to enter multiple commands

<span style="background-color:#282c34"><span style="color:#282c34"> <span style="color:#abb2bf">vim test.config.simple</span>
 <span style="color:#abb2bf">[root@localhost opt]# ll</span>
 <span style="color:#abb2bf">total 4</span>
 <span style="color:#abb2bf">drwxr-xr-x 2 root root  6 Dec 15 20:50 D1</span>
 <span style="color:#abb2bf">drwxr-xr-x 2 root root  6 Dec 15 20:49 D2</span>
 <span style="color:#abb2bf">drwxr-xr-x 2 root root  6 Dec 15 20:50 D3</span>
 <span style="color:#abb2bf">-rw-r--r-- 1 root root 10 Dec 15 20:57 test.config</span>
 <span style="color:#abb2bf">[root@localhost opt]# mv test.config{.simple,}</span>
 <span style="color:#abb2bf">[root@localhost opt]# ls</span>
 <span style="color:#abb2bf">D1  D2  D3  test.config</span></span></span>

8, Text editor vim

1. Basic grammar

  • vi is a text editor, and vi tools are installed by default in most distributions

  • vim is an upgraded version of vi

  • vim features:

    • Different colors are displayed in the text, and the administrator can identify the errors in the text by color

    • Support block diagram mode

    • Many software also use vi editing methods by default, such as crontab (scheduled task)

<span style="background-color:#282c34"><span style="color:#282c34"> <span style="color:#abb2bf">vim file1</span>
 <span style="color:#Abb2bf "> A / / input mode</span>
 <span style="color:#Abb2bf ">: WQ / / save push</span></span></span>

2. Working mode of VI editor

Command mode (general mode): used to move the cursor, copy and delete lines

Input mode (edit mode): edit text

Last line mode (command line mode): used to set environment, line number, tab and indentation.

Command mode to enter input mode:

oEnter the next line of the current character
iEnter before current character
aEnter after current character
IInput at the beginning of the current line
ACurrent line end input
OInput on the previous line of the current line
sEnter after deleting the current character
SEnter after deleting the current line
Home keyLine beginning
End keyEnd of line

Command mode cursor control:

letterCursor movement
↑↓←→Up, down, left and right
0 or ^Position the cursor at the beginning of the line
$Position the cursor at the end of the line
ggPosition the cursor at the beginning of the article
GPosition the cursor at the end of the article
nGN stands for number, that is, move the cursor to line n
nyyN stands for number, copy n lines
shift+v+↑↓←→+yy+pSelect the row you want to copy in the visual interface
vVisualization mode
ctrl+vVisualization mode block

Tips: how to add #?

ctrl+v select shift+i and enter #ESC

Copy paste delete

yyCopy a row
d^Deletes the current character to the beginning of the line
d$Delete current character to end of line
dggDelete current row to first row
dGDelete current line to last line

Last line mode

:wSave exit
:qsign out
:wqSave exit
:w!Force save
:q!forced return
:wq!Force save exit
:w /tmp/cc.txtSave as
:! commendTemporarily enter linux commands
:e /root/aa.txtOpen a file
:e!Reopen this file (refresh)
:setView all environment settings
:set nu/:set nonuView line number / cancel line number
:set tabstop=16Set the tab to 16 bytes in length
:set autoindentAuto indent
/Keywords, N, nSearch from top to bottom, n next, n previous
? keywordSearch from bottom to top, n previous, n next
:nohCancel highlight mode

3. vim profile:

<span style="background-color:#282c34"><span style="color:#282c34"> <span style="color:#Abb2bf "> VIM ~ /. Vimrc / / permanently add a line number for an individual. Enable the line number function</span>
 <span style="color:#Abb2bf "> VIM / etc / vimrc / / permanently added for everyone, in the last line</span></span></span>

4. Substitution syntax:


s: OK

g: To the end of the line

%: Global

Last line modemeaning
:s/ab/xx/Replace the first matching string on the current line
:s/ab/xx/gReplace all matching strings in the current line
:%s/ab/xx/gReplace matching strings in all rows
:3,5s/ab/xx/gReplace lines 3 to 5

5. vim exchange file:

Premise: if two terminals open the same file, they will be prompted

If the machine goes down, the file exchange will record the operation of the file and prompt for reply, deletion and other operations

Window 1:

<span style="background-color:#282c34"><span style="color:#282c34"> <span style="color:#abb2bf">cd ~</span>
 <span style="color:#abb2bf">vim 1.txt</span>
 <span style="color:#Abb2bf "> Ctrl + Z / / put vim applications in the background</span></span></span>

Window 2

<span style="background-color:#282c34"><span style="color:#282c34"> <span style="color:#abb2bf">[root@localhost /]# cd ~;vim 1.txt / / the swap file appears</span></span></span>


Delete duplicate open file processes and delete swap files

<span style="background-color:#282c34"><span style="color:#282c34"> <span style="color:#Abb2bf "> jobs - L / / view the daemon directory for details</span>
 <span style="color:#Abb2bf "> PS - EF / / view the process</span>
 <span style="color:#abb2bf">kill -9 24234</span></span></span>

Open any window again, delete the exchange file, save and exit.

9, Script bash

<span style="background-color:#282c34"><span style="color:#282c34"> <span style="color:#Abb2bf "> VIM / / the script must be given permission and the first line</span>
 <span style="color:#abb2bf">chmod +x</span>
 <span style="color:#abb2bf">#!/ bin/bash / / the first line of the script</span>
 <span style="color:#Abb2bf "> date / / content</span>
 <span style="color:#Abb2bf ">. / / / running</span>
 <span style="color:#abb2bf">Thu 16 Dec 09:43:39 CST 2021</span></span></span>

Keywords: Linux Operation & Maintenance CentOS vim

Added by Craig_H on Sat, 08 Jan 2022 22:59:53 +0200