Admin (a)--linux introduction and Simple command

First, the difference between RHEL and CentOS

Rhel is a commercially available Linux system provided by Red Hat, which typically requires a paid subscription for technical service support such as DVD mirroring, security updates, but the various packages that make up the Rhel system are released free of charge based on the GPL open source protocol.

CentOS is a community-based Linux system, equivalent to a cloned version of Rhel, which is reassembled and developed using the various software packages that make up the Rhel system, with some optimizations and necessary bug fixes in the process , the CentOS system version will be released slightly later than the same version of the RHEL system, its composition, management and the same version of the RHEL system is almost identical, and can find a large number of open software sources, so many enterprises are welcomed.

Second, the Linux file system

Basic role: Defines methods and data structures for storing documents on disk media, and rules for reading documents. Different types of file systems, which are stored and read differently. The format operation is to create a new file system.

Typical file system types are:

-EXT4 fourth-generation extended file system, RHEL6 series default

-XFS (processing large data volumes) Advanced log file system, RHEL7 series default

-Swap swap space (virtual memory)

Ii. basic operation of Linux command line

1. Console switch

The RHEL7 system provides 6 virtual consoles (TTY1~TTY6) by default, and each console can log on independently and perform different tasks. Where Tty1, Tty2 turn on the graphical desktop by default, TTY3~TTY6 only the character mode. By combining shortcut keys CTRL+ALT+FN can switch between different virtual consoles, where FN represents one of the F1~F6 keys. For example, when you are on a normal graphical desktop, press CTRL+ALT+F3 to switch to console tty3, enter the command-line interface for pure character mode after logging in, and then press the CTRL+ALT+F1 key combination if you need to return to the previous graphical desktop.

The meaning of the command-line prompt identity:

[Current user @ hostname working directory]$

If the current user is root, the last character is #, otherwise the last character is $

2, Linux simple command

Check Red Hat release information: #cat, Etc/redhat-release

List kernel versions: #uname-R

View current host Name: #hostname

View current working directory #pwd

Switch working directory: #cd plus path CD. Return to the previous layer

View Directory contents: #ls Plus path (does not display the current directory content)

View IP Address: #ifconfig

Temporarily configure IP address (fails on restart): #ifconfig eth0 192.168.1.1/24

View CPU Processor information: #lscpu or #cat Proc/cpuinfo

To view memory size, idle condition: #cat/proc/meminfo

Shutdown: #poweroff

Restart: #reboot

View text file contents: #cat Plus file path

or #less plus file path (q key exit)

View text file Part content: #head-n Look at the top n rows

#tail-N View after n rows

Create directory: #mkdir/root/111 Create a directory named 111 under/root

Create a text file: Touch/root/111/abc.txt Create a TXT file named ABC under/root/111

Find the line containing the specified string from the text file: #grep ' root '/etc/passwd find the row containing the root in the file/etc/passwd

Admin (a)--linux introduction and Simple command