Basic commands and document structure

Basic commands:

Whoami # View the currently logged in user

Uname-r # check the kernel version number

Cat / etc/redhat-release # View system version

Cat / proc/cpuinfo # View CPU related information

Cat / proc/meminfo # View memory related information

Ifconfig eth0 # View IP address

Ifconfig eth0 IP # set IP address (effective temporarily)

Shutdown command:

Init 0

Halt

Poweroff

Shutdown-h now

Restart class command:

Init 6

Reboot

Shutdown-r now

Postpone shutdown:

Shutdown-h + 15 "The system in 15 minutes after the explosion"

Cancel:

Shutdown-c & & Ctrl+c

Cat:

The purpose of the command is to connect files or standard input and print. This command is often used to display the contents of a file, to connect several files to display, or to read and display the contents from standard input, and it is often used in conjunction with redirection symbols.

1. Command format:

Cat [options] [files]...

2. Command function:

Cat has three main functions:

1. Show the entire file at once: cat filename

two。 Create a file from the keyboard: cat > filename can only create new files, not edit existing files.

3. Merge several files into one file: cat file1 file2 > file

3. Command parameters:

-A,-- show-all is equivalent to-vET

-b,-- number-nonblank to the non-empty outgoing line number

-e is equivalent to-vE

-E,-- show-ends displays $at the end of each line

-n,-- number numbers all lines of output, starting with 1, numbers all lines of output

-s,-- squeeze-blank has more than two blank lines in a row, so replace it with a blank line

-t is equivalent to-vT

-T,-- show-tabs displays tabbed characters as ^ I.

-u (ignored)

-v,-- show-nonprinting uses ^ and M-references, except for LFD and TAB

Mkdir:

Format: mkdir [- mp] directory

Function: create a new directory

Description of common options:

-p create multiple recursive directories directly

-m set the permissions of the file directly, regardless of the default permissions

[example]: [root@dsetl etc] # cd / tmp

[root@dsetl tmp] # mkdir lp-create directory lp

[root@dsetl tmp] # mkdir-p test1/test2/test3-- create multiple recursive directories directly

Example: create a directory with permissions of 777

Command:

Mkdir-m 777 test3

Output:

[root@localhost test] # mkdir-m 777 test3

[root@localhost test] # ll

Total 12drwxr-xr-x 2 root root 4096 10-25 17:42 test1

Drwxr-xr-x 3 root root 4096 10-25 17:44 test2

Drwxrwxrwx 2 root root 4096 10-25 17:46 test3

[root@localhost test] #

Description:

The permission of test3 is rwxrwxrwx

File directory:

Directory structure of Linux

"/"

| |

| | |

/ root / bin / boot / dev / etc / home / var / lib / usr / media / tmp.

| | |

| | |

/ root/Desktop / root/Maildir. / usr/bin / usr/src / usr/local

/ starting point of the root partition linux file system

/ bin normal command

Commands of the / sbin management class, which only administrators can use

/ home ordinary user's host directory (home directory) for example: bob user's host directory is / home/bob

/ root administrator's host directory

/ boot linux required files for startup, kernel, grub, kernel boot files

/ dev device files, hard disk, keyboard and mouse, optical drive, etc.

/ usr stores application-related files / usr/src: the decompression path of the source package / usr/local: the installation path of the source package

/ opt the storage path when installing additional software

/ etc configuration file

/ var stores variable files, log files, mail, etc.

/ proc virtual file system (computer kernel information, CPU...) does not occupy the real space of the hard disk, and the data is in memory

/ lib library file, driver

/ selinux Security mechanisms developed by the U.S. National Security Agency

/ tmp temporary file storage directory (public folder)

/ media mount point is equivalent to / mnt

/ sys system related files

The data directory that needs to be accessed by the service started by srv