004---Linux系统设置

Linux版本相关命令

查看系统版本：cat /etc/redhat-release
查看系统内核版本以及位数：uname -r

[root@hostname1 ~]# cat /etc/redhat-release 
CentOS Linux release 7.6.1810 (Core) 
[root@hostname1 ~]# uname -r
3.10.0-957.el7.x86_64

PS1

变量名，系统变量一般都是大写。

[root@hostname1 ~]# echo $PS1
[u@h W]$
[root@hostname1 ~]# # u-->当前用户名：whoami
[root@hostname1 ~]# # h-->当前主机名：hostname
[root@hostname1 ~]# # W-->当前目录：pwd
[root@hostname1 ~]# whoami
root
[root@hostname1 ~]# hostname
hostname1
[root@hostname1 ~]# pwd
/root

修改PS1：加时间

[root@hostname1 ~]# PS1='[u@h W 	]$'
[root@hostname1 ~ 20:34:51]#

linux系统优化

用户

添加用户：useradd JiangZiYa
查看用户：id JiangZiYa
修改密码:passwd JiangZiYa
查看当前用户：whoami
切换用户：su - JiangZiYa
切换root用户：su - or su - root
注销用户：logout or ctrl + D

[root@hostname1 ~]# useradd JiangZiYa
[root@hostname1 ~]# id JiangZiYa
uid=1000(JiangZiYa) gid=1000(JiangZiYa) groups=1000(JiangZiYa)
[root@hostname1 ~]# id user
id: user: no such user
[root@hostname1 ~]# passwd JiangZiYa
Changing password for user JiangZiYa.
New password: 
Retype new password: 
passwd: all authentication tokens updated successfully.

[root@hostname1 ~]# whoami
root
[root@hostname1 ~]# su - JiangZiYa
Last login: Mon Feb  4 21:11:38 CST 2019 on pts/0
[JiangZiYa@hostname1 ~]$ whoami
JiangZiYa
[JiangZiYa@hostname1 ~]$ su -
Password: 
Last login: Mon Feb  4 21:11:24 CST 2019 on pts/0
[root@hostname1 ~]# logout
[JiangZiYa@hostname1 ~]$

关闭SELinux

查询状态：getenforce
- Enforcing：正在执行
- Permissive：临时关闭，还是提示警告
- Disabled ：彻底关闭

[JiangZiYa@hostname1 ~]$ getenforce 
Enforcing

[root@hostname1 ~]# getenforce 
Permissive

[root@hostname1 ~]# getenforce
Disabled

临时关闭：setenforce 0

[root@hostname1 ~]# setenforce 0

永久关闭：vim /etc/sysconfig/selinux

SELINUX=disabled

重启生效

关闭防火墙

查看防火墙状态：systemctl status firewalld or firewall-cmd --state

[root@hostname1 ~]# systemctl status firewalld
● firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2019-02-04 21:43:15 CST; 1min 50s ago
     Docs: man:firewalld(1)
 Main PID: 6308 (firewalld)
   CGroup: /system.slice/firewalld.service
           └─6308 /usr/bin/python -Es /usr/sbin/firewalld --nofork --nopid

Feb 04 21:43:13 hostname1 systemd[1]: Starting firewalld - dynamic firewall daemon...
Feb 04 21:43:15 hostname1 systemd[1]: Started firewalld - dynamic firewall daemon.

[root@hostname1 ~]# firewall-cmd --state
running

临时关闭防火墙：systemctl stop firewalld

[root@hostname1 ~]# systemctl stop firewalld
[root@hostname1 ~]# systemctl status firewalld
● firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
   Active: inactive (dead) since Mon 2019-02-04 21:45:58 CST; 1s ago
     Docs: man:firewalld(1)
  Process: 6308 ExecStart=/usr/sbin/firewalld --nofork --nopid $FIREWALLD_ARGS (code=exited, status=0/SUCCESS)
 Main PID: 6308 (code=exited, status=0/SUCCESS)

Feb 04 21:43:13 hostname1 systemd[1]: Starting firewalld - dynamic firewall daemon...
Feb 04 21:43:15 hostname1 systemd[1]: Started firewalld - dynamic firewall daemon.
Feb 04 21:45:57 hostname1 systemd[1]: Stopping firewalld - dynamic firewall daemon...
Feb 04 21:45:58 hostname1 systemd[1]: Stopped firewalld - dynamic firewall daemon.
[root@hostname1 ~]#

永久关闭防火墙：systemctl disable firewalld

[root@hostname1 ~]# systemctl disable firewalld

[root@hostname1 ~]# reboot

Connecting to 10.0.0.128:22...
Could not connect to '10.0.0.128' (port 22): Connection failed.

Type `help' to learn how to use Xshell prompt.
[c:~]$ 

Connecting to 10.0.0.128:22...
Connection established.
To escape to local shell, press 'Ctrl+Alt+]'.

Last login: Mon Feb  4 21:52:23 2019 from 10.0.0.1
[root@hostname1 ~]# systemctl status firewalld
● firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; disabled; vendor preset: enabled)
   Active: inactive (dead)
     Docs: man:firewalld(1)
[root@hostname1 ~]# firewall-cmd --state
not running

重启防火墙：systemctl restart firewalld