Linux system optimization + scheduled tasks

install software

Install via yum

Autocomplete tool: yum completion

yum install -y  tree bash-completion  wget vim

find -[TAB]

 

Change the yum source of the system, Alibaba Cloud

Ali Cloud

Linux can not access the Internet troubleshooting process 
 1. Check whether you can access the Internet
[root@bigdata ~]# ping baidu.com
connect: network unreachable

2. Verify whether the DNS domain name resolves the domain name ----> ip address
[root@bigdata ~]# ping 223.5.5.5
connect: network unreachable

3. Gateway - Verify that your network configuration (NIC virtual machine vmwarexxx) is not the problem
ip   r     
[root@bigdata ~]# ping 10.0.0.2
PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data.
64 bytes from 10.0.0.2: icmp_seq=1 ttl=128 time=0.206 ms
64 bytes from 10.0.0.2: icmp_seq=2 ttl=128 time=0.170 ms
^C
--- 10.0.0.2 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1000ms
rtt min/avg/max/mdev = 0.170/0.188/0.206/0.018 ms

How to download software when the virtual machine cannot access the Internet

Install from CD

Query installed software

close SElinux

permanent

Need to restart the server to take effect

Backup is required before operation

 

 Temporary (used when the server cannot be restarted (restart fails))

[root@jassin- 01 ~ ]# # Display current selinux
[root@jassin - 01 ~ ]# #Display the current running status of selinux
[root@jassin - 01 ~ ]# setenforce
usage:  setenforce [ Enforcing | Permissive | 1 | 0 ]
[root@jassin - 01 ~]# setenforce 0 
[root@jassin - 01 ~ ]# geten
getenforce  getent      
[root@jassin - 01 ~ ]# getenforce
Permissive
[root@jassin-01 ~]# 

 firewall

[root@jassin- 01 ~ ]# # Query firewall status
[root@jassin-01 ~]# systemctl status firewalld.service 

Stop the currently running firewall -   temporary
systemctl stop firewalld.service

Let the firewall start without booting   ----    permanent
systemctl disable firewalld.service

[root@jassin- 01 ~]# # systemctl is - active firewalld.service 
 # is - active is it running or not
[root@jassin - 01 ~]# # systemctl is - enabled firewalld.service 
 # is - enabled Whether to start automatically at boot
[root@jassin-01 ~]# systemctl is-active firewalld.service 
unknown
[root@jassin-01 ~]# systemctl is-enabled firewalld.service 
disabled

disabled   --> indicates that the boot will not start automatically
When the names are the same, systemctl start firewalld.service

 will be started automatically.