Install the Linux operating system
1. red had linux version
Red Hat Enterprise Edition: Red Hat Enterprise Linux (RHEL for short); official website: http://www.redhat.com
Fedora Community Edition : Community maintenance funded by Red Hat, positioned for personal desktop use; official website: http://fedoraproject.org
CentOS Community Edition : Community Enterprise Operating System official website: http://www.centos.org
2. File system type
The file system type currently used by RHEL6 by default : EXT4, the fourth generation extended (Extended) file system
; SWAP, swap file system
Other file system types supported by Linux : FAT16, FAT32, NTFS; XFS, JFS
3. Initialization and boot process
4. init process
The Linux kernel loads and runs the /sbin/init program: it is the first process in the system; the PID (process mark) number is always 1
5.Upstart startup method
inittab configuration file : scattered storage of various initialization configurations; corresponding related startup events
Partial upstart startup configuration file table
| parameter |
illustrate |
| /etc/inittab |
Configure the default runlevel |
| /etc/sysconfig/init |
Control the number of tty terminals opened and the terminal color scheme |
| /etc/init/rcS.conf |
Load the rc.sysinit script to complete the system initialization task |
| /etc/init/rc.conf |
Compatible script, responsible for call processing at each run level |
| /etc/init/rcS-sulogin.conf |
Start the /sbin/sushell environment for single-user mode |
| /etc/init/control-alt-delete.conf |
Ctrl+Alt+Del hotkey operation under the control terminal |
| /etc/init/start-ttys.conf |
Configure the number of open tty terminals and device files |
| /etc/init/tty.conf |
Control the opening of the tty terminal |
6. Structure of the inittab file
View the init program configuration: cat /etc/inittab
Syntax: id:runlevels:action :process
| field |
illustrate |
| id |
Used to uniquely identify a configuration record in the inittab file |
| runlevels |
Used to specify in which runlevels this record runs |
| action |
Used to describe what type of action the record will perform |
| process |
Used to set the command executed by the startup process |
runlevels - run levels
| runlevel |
illustrate |
| 0 |
Shutdown state, using this level will shut down the host |
| 1 |
Single-user mode, you can log in to the system without password authentication, mostly used for system maintenance |
| 2 |
Multi-user mode with character interface (does not support network access) |
| 3 |
Full multi-user mode with character interface, most server hosts run at this level |
| 4 |
Not allocated for use |
| 5 |
The multi-user mode of the graphical interface provides a graphical desktop operating environment |
| 6 |
Reboot, using this level will reboot the host |
Note: Only the default runlevel configuration is kept in the /etc/inittab file of RHEL6
7. System service control
Syntax: service service name control type or /etc/rc.d/init.d service name control type
Control type: start: start; stop: stop; restart: restart; reload: reload status: view service status
Use the service tool or the system service script in the /etc/init.d directory to start, restart, and stop system services
8. Runlevels
View: Use the runlevel command to display: the run level before the switch, the current run level
Temporary switch: use init command with 0-6 runlevel parameters
[root@localhost ~]# runlevel
5 3
[root@localhost ~]# init 6 (reboot system)
[root@localhost ~]# init 0 (shut down the system)
9. Optimize the startup process
ntsysv tool: Provides an interactive, visual window; can be run on a character terminal; facilitates centralized management of multiple services
Syntax: ntsysv; ntsysv --level level list
chkconfig tool: similar to the ntsysv tool but does not provide an interactive, visual window; it is more efficient to manage a single service
10. Startup and control of system services
Check the startup status of system services
Syntax: chkconfig –list View the default startup status of all services
chkconfig --list service name View the default startup status of the specified service
Set the startup status of system services
Syntax: chkconfig --level level list service name on|off
Directory and File Management
1. Classification of Linux commands
Purpose: An instruction or program used to implement a certain type of function; the execution of the command depends on the interpreter program (for example: /bin/bash)
Classification
Internal command: part of the shell interpreter
External commands: program files independent of the shell interpreter
2. Format of Linux commands
Syntax: command word [options] [parameters]
Options: Used to adjust the specific function of the command
Short format options (single characters) are preceded by "-", e.g. "-l"
Leading long format options (multiple characters) with "--", e.g. "--color"
Multiple short-form options can be written together, only preceded by a "-", e.g. "-al"
Parameters: The object of the command operation, such as file, directory name, etc.
Several auxiliary operations of command line editing
Tab key: auto-completion
Backslash "\": Force newline
Shortcut Ctrl+U: Clear to the beginning of the line
Shortcut Ctrl+K: Clear to end of line
Shortcut Ctrl+L: Clear the screen
Shortcut Ctrl+C: Cancel the editing of this command
3. Basic commands
1 ): cat command : display the content of the file
Syntax: cat [options] filename...
2 ): more command/less command : paging display file content in full screen mode
Syntax: more/less [options] filename…
Interactive operation method: press Enter to scroll down line by line; press space bar to scroll down one screen; press q to exit/Page Up to page up, Page Down to page down; press "/" to find content, "n" "The next content, "N" the previous content; other functions are basically similar to the more command
3 ): head command/tail command: view part of the beginning/end of the file (default is 10 lines)
Syntax: head /tail -n filename…
4 ): wc command: count the number of words in the file (Word Count). The number of lines and other information
Syntax: wc [options]... object file...
Common command options : -l: count lines; -w: count words; -c: count bytes
E.g.[root@localhost ~]# wc /etc/hosts
4 23 185 /etc/hosts ( 4 lines, 23 words, 185 bytes )
5 ): grep command : find and display lines in a file that contain the specified string
Syntax: grep [options]... Find conditional object files
Common command options: -i: ignore case when searching (ignore case); -v: reverse the search (invert), output lines that do not match the search conditions
Search condition setting: the string to be searched is enclosed in double quotation marks; "^..." means start with..., "...$" means end with...; "^$" means blank line
6 ): gzip command, bzip2 command: make compressed files, unzip compressed files
Syntax: gzip [-9] filename...
bzip2 [-9] filename... (makes compressed file)
gzip -d compressed file in .gz format
bzip2 -d compressed file in .bz2 format (uncompressed file)
Common command options: -9: indicates a high compression ratio, which is mostly used when creating compressed packages; -d: used to unzip already compressed files
Note: The compression algorithms used by the gzip and bzip2 commands are different . Generally speaking , the compression efficiency of bzip2 is better.
8 ): tar command : make archive files, release archive files
Syntax: tar [options] ... archive filename source file or directory
tar [options]...archive_filename [-C target_dir]
Common command options:
-c: Create a package file in .tar format
-x: Unpack the package file in .tar format
-v: output verbose information
-f: indicates use of archive files
-p: preserve the permissions of the original files and directories when packaging
-t: List view files in the package
-C: Specify the target folder to be released when unpacking
-z: call the gzip program to compress or decompress
-j: call the bzip2 program to compress or decompress
4. Text editor
There are many configuration files in Linux, similar to the registry in windows; the default is managed and maintained by the vi editor (text editing tool); vim is an enhanced version.
Three working modes: command mode, input mode, last line mode
Switch between different modes
Basic command operations
| Operation type |
Action keys |
Function |
| Mode switch |
a |
Insert content after the current cursor position |
|
|
i |
Insert content before the current cursor position |
|
|
o / O |
Insert a new line after/before the current cursor line |
| Cursor movement direction |
á 、 â 、 ß 、 à |
up down left right |
| Quick jump in line line number display |
Home key or "^"/End key or "$" : set nu /: set nonu |
Jump to beginning/end of line Display line number/cancel line number display |
| delete |
x or Del |
Delete a single character at the cursor |
|
|
dd |
delete the current cursor line |
|
|
#dd |
Delete the #line content starting at the cursor |
|
|
d^ |
Delete all characters from the current cursor to the beginning of the line |
|
|
d$ |
Delete all characters from the current cursor to the end of the line |
| copy |
yy |
Copy the entire content of the current line to the clipboard |
|
|
#yy |
Copy the contents of the #line starting at the cursor |
| paste |
P (large) |
before pasting at the cursor position |
|
|
p |
Paste the contents of the buffer after the cursor position |
| save and exit |
：wq |
Save changes and exit |
| quit |
：q! |
Abandon the modified file and exit |
| Save as |
：w /root/newfile |
Save as… |
| Find file contents |
/word /?word |
Find the string "word" from top to bottom/bottom to top |
|
|
n/N |
locate the next/previous matching string to be searched for |
| Undo edit |
u |
Press once to cancel the most recent action, and so on |
|
|
U |
Used to cancel all edits made to the current line |
| save and exit |
ZZ |
Save the current file contents and exit the vi editor |
| Open new file |
:e ~/install.log |
Open a new file for editing |
| read other content |
:r /etc/filesystems |
Read the contents of other files in the current file |
| file content replacement |
:s /old/new |
Replace the first "old" found with "new" |
|
|
:s /old/new/g |
Replace all "old" found with "new" |
|
|
:#,# s/old/new/g |
Replace all "old" with "new" in the range "#,#" |
|
|
:% s/old/new/g |
Replace all "old" with "new" throughout the file |
|
|
:s /old/new/c |
Add the c command at the end of the replacement command to prompt for confirmation |