信息显示和搜索命令

[root@#quan#Better ~]$uname -r #显示内核发行版本号
2.6.32-696.el6.x86_64
[root@#quan#Better ~]$uname -n #显示主机名
Better
[root@#quan#Better ~]$uname -v  #显示内核版本
#1 SMP Tue Mar 21 19:29:05 UTC 2017
[root@#quan#Better ~]$uname -m  #显示计算机架构
x86_64
[root@#quan#Better ~]$

[root@#quan#Better ~]$hostname  
Better
[root@#quan#Better ~]$hostname AAA  #临时修改主机名
[root@#quan#Better ~]$vim /etc/sysconfig/network  #永久修改主机名
[root@#quan#Better ~]$cat /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=Better
NTPSERVERARGS=iburst
[root@#quan#Better ~]$

[root@#quan#Better ~]$cat /etc/hosts   #配置主机hosts解析
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

[root@#quan#Better ~]$hostname -I #获取系统IP地址，多少个网卡就多少个IP地址
192.168.139.128 192.168.31.66 
[root@#quan#Better ~]$

dmesg 用于显示内核环形缓冲区的内容，在系统引导市，内核会将硬件和模块初始化相关信息写到这个缓冲区中，/var/log/dmesg
[root@#quan#Better ~]$dmesg |less


Initializing cgroup subsys cpuset
Initializing cgroup subsys cpu
Linux version 2.6.32-696.el6.x86_64 (mockbuild@c1bm.rdu2.centos.org) (gcc version 4.4.7 20120313 (Red Hat 4.4.7-18) (GCC) ) #1 SMP Tue Mar 21 19:29:05 UTC 2017
Command line: ro root=UUID=bedc9145

stat:详细显示文件或者文件系统的状态信息
[root@#quan#Better ~]$stat /etc/hosts
  File: `/etc/hosts‘
  Size: 158           Blocks: 8          IO Block: 4096   regular file
Device: 805h/2053d    Inode: 1179681     Links: 1
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2019-09-14 23:04:36.745216799 +0800
Modify: 2010-01-12 21:28:22.000000000 +0800
Change: 2019-07-27 19:00:34.411999909 +0800
#获取文件对应的权限对应的数字内容
[root@#quan#Better ~]$stat -c %a /etc/hosts
644

du统计磁盘空间使用情况，可以查找那个文件过多使用磁盘空间
[root@#quan#Better tmp]$du -a  #显示所有文件的大小，包括隐藏文件和目录下所有子文件
280    ./zabbix_server.log
0    ./.esd-0/socket
4    ./.esd-0
4    ./sess_tvr0so89lsjuv3hkpsskira1g3
0    ./pulse-DQ6pTKVyMQbA/native
4    ./pulse-DQ6pTKVyMQbA
0    ./keyring-95urfx/socket.pkcs11
0    ./keyring-95urfx/socket
0    ./keyring-95urfx/socket.ssh
4    ./keyring-95urfx
0    ./keyring-AGHgFM/socket.pkcs11
0    ./keyring-AGHgFM/socket
[root@#quan#Better tmp]$du -s 显示文件总大小
392    .
[root@#quan#Better tmp]$du -h  人性化显示
4.0K    ./.esd-0
4.0K    ./pulse-DQ6pTKVyMQbA
4.0K    ./keyring-95urfx
4.0K    ./keyring-AGHgFM
4.0K    ./.ICE-unix
4.0K    ./keyring-z210kg
4.0K    ./keyring-Qhfnnd
4.0K    ./keyring-vU6ECi
24K    ./gconfd-gdm
8.0K    ./orbit-gdm
4.0K    ./keyring-hRsO0e
8.0K    ./pulse-dLTEGSQL3ge3
4.0K    ./keyring-SYAqed
4.0K    ./keyring-wlVYuR
4.0K    ./keyring-Foz4Hv
4.0K    ./.X11-unix
392K    .
[root@#quan#Better tmp]$du -sh
392K    .

[root@#quan#Better tmp]$date +%y
19
[root@#quan#Better tmp]$date +%Y
2019
[root@#quan#Better tmp]$date +%m
09
[root@#quan#Better tmp]$date +%d
15
[root@#quan#Better tmp]$date +%H
16
[root@#quan#Better tmp]$date +%M
41
[root@#quan#Better tmp]$date +%S
25
[root@#quan#Better tmp]$date +%F
2019-09-15
[root@#quan#Better tmp]$date +%T
16:41:37
[root@#quan#Better tmp]$date +%F -d "-1day"
2019-09-14
[root@#quan#Better tmp]$date +%F -d "-2day"
2019-09-13
[root@#quan#Better tmp]$date +%F -d "-1month"
2019-08-15

[root@#quan#Better tmp]$date -d "Thu May 6 21:41:16 CST 2019" "+%Y-%m-%d %H-%M-%S"
2019-05-06 21-41-16

[root@#quan#Better tmp]$which hostname  #显示命令的全路径，通过PATH环境变量的路径
/bin/hostname
[root@#quan#Better tmp]$which -a hostname  #-a 一班是查找到就停止，不过现在遍历PATH 路径查找
/bin/hostname

[root@#quan#Better tmp]$whereis which
which: /usr/bin/which /usr/share/man/man1/which.1.gz

#查看文件的可执行文件和源码文件及man帮助文件的路径

locate 快速定位文件的路径
linux系统里面有一个mlocate.db的数据库文件，里面包含文件系统的文件名对应的路径星系，所有不要遍历磁盘，而是直接找数据库文件，
注意：如果是新加的文件，mlocate.db是没有记录的，所有要使用updatedb命令跟新数据库文件。
[root@#quan#Better tmp]$ll -h /var/lib/mlocate/mlocate.db 
-rw-r----- 1 root slocate 3.8M Sep 15 03:06 /var/lib/mlocate/mlocate.db
     
[root@#quan#Better tmp]$cat /etc/cron.daily/mlocate.cron 
#!/bin/sh
nodevs=$(< /proc/filesystems awk ‘$1 == "nodev" && $2 != "zfs" { print $2 }‘)
renice +19 -p $$ >/dev/null 2>&1
ionice -c2 -n7 -p $$ >/dev/null 2>&1
/usr/bin/updatedb -f "$nodevs"
[root@#quan#Better tmp]$