查询系统准确的启动时间

```

[root@test~]date-d"$(awk-F.'{print$1}'/proc/uptime)secondago"+"%Y-%m-%d%H:%M:%S"

2018-01-1914:45:35

[root@test~]

```

查询所有进程的准确启动时间和运行时长

-e表示查询所有进程

-o表示按指定的格式输出

lstart为进程启动时间

etime可以显示已经运行了多长时间

args为具体的命令行参数

[root@test~]date-s"2018/01/2223:29"

MonJan2223:29:00CST2018

[root@test~]timedatectlset-ntp0

[root@test~]timedatectlset-ntp1

[root@test~]

```

同步OS与硬件时间

将OS系统时间同步到硬件(RTC)

hwclock–-systohc

将硬件时间同步到OS

hwclock--hctosys

```

[root@test~]hwclock--systohc

[root@test~]

```

查看硬件信息

lscpu查看PCI信息

lsusb查看SCSI设备

lsblk查内存槽位信息.不跟-t,查全量processor,Memory,BIOS

```

[root@test~]lsusb

Bus002Device002:ID0627:0001AdomaxTechnologyCo.,Ltd

Bus001Device001:ID1d6b:0002

Bus002Device001:ID1d6b:0001

[root@test~]yum-yinstalllsscsi

[root@test~]lsblk

NAMEMAJ:MINRMSIZEROTYPEMOUNTPOINT

xvda202:0040G0disk

├─xvda1202:10500M0part/boot

└─xvda2202:2039.5G0part/

[root@test~]dmidecode-tmemory

[root@test~]

11structuresoccupying346bytes.

Tableat0xFC001000.

Handle0x0000,DMItype0,24bytes

BIOSInformation

Vor:Xen

Version:Unknown

ReleaseDate:09/26/2017

Address:0xE8000

RuntimeSize:96kB

ROMSize:64kB

Characteristics:

PCIissupported

EDDissupported

Targetedcontentdistributionissupported

BIOSRevision:0.0

Handle0x0100,DMItype1,27bytes

SystemInformation

Manufacturer:Xen

ProductName:HVMdomU

Version:Unknown

SerialNumber:3e56659c-96ac-4c5c-b4f8-fd48d730e3e7

UUID:3E56659C-96AC-4C5C-B4F8-FD48D730E3E7

Wake-upType:PowerSwitch

SKUNumber:NotSpecified

Family:NotSpecified

Handle0x0300,DMItype3,13bytes

ChassisInformation

Manufacturer:Xen

Type:Other

Lock:NotPresent

Version:NotSpecified

SerialNumber:NotSpecified

AssetTag:NotSpecified

Boot-upState:Safe

PowerSupplyState:Safe

ThermalState:Safe

SecurityStatus:Unknown

Handle0x0401,DMItype4,26bytes

ProcessorInformation

SocketDesignation:CPU1

Type:CentralProcessor

Family:Other

Manufacturer:Intel

ID:F2060300FFFB8917

Version:Intel(R)Xeon(R)CPUE5-2680v3@2.50GHz

Voltage:Unknown

ExternalClock:Unknown

MaxSpeed:2494MHz

CurrentSpeed:2494MHz

Status:Populated,Enabled

Upgrade:Other

Handle0x0B00,DMItype11,5bytes

OEMStrings

String1:Xen

Handle0x1000,DMItype16,15bytes

PhysicalMemoryArray

Location:Other

Use:SystemMemory

ErrorCorrectionType:Multi-bitECC

MaximumCapacity:1016MB

ErrorInformationHandle:NotProvided

NumberOfDevices:1

Handle0x1100,DMItype17,21bytes

MemoryDevice

ArrayHandle:0x1000

ErrorInformationHandle:0x0000

TotalWidth:64bits

DataWidth:64bits

Size:1016MB

FormFactor:DIMM

Set:None

Locator:DIMM0

BankLocator:NotSpecified

Type:RAM

TypeDetail:None

Handle0x1300,DMItype19,15bytes

MemoryArrayMappedAddress

StartingAddress:0x00000000000

ingAddress:0x0003F7FFFFF

RangeSize:1016MB

PhysicalArrayHandle:0x1000

PartitionWidth:1

Handle0x1400,DMItype20,19bytes

MemoryDeviceMappedAddress

StartingAddress:0x00000000000

ingAddress:0x0003F7FFFFF

RangeSize:1016MB

PhysicalDeviceHandle:0x1100

MemoryArrayMappedAddressHandle:0x1300

PartitionRowPosition:1

Handle0x2000,DMItype32,11bytes

SystemBootInformation

Status:Noerrorsdetected

Handle0x7F00,DMItype127,4bytes

OfTable

```

锁定文件,不被任何程序修改

chattr可以改变文件扩展属性,chattr+i可以防止任何程序修改该文件.即使有root权限.

常用于锁定dns配置,防止dhcp程序自动修改.lsattr查看当前的扩展属性.manchattr查看所有参数含义.

chattr+i/etc/

```

[root@test~]lsattr/etc/

-------------e--/etc/

[root@test~]lsattr/etc/

----i--------e--/etc/

[root@test~]lsattr/etc/

-------------e--/etc/

[root@test~]stat/var/log/messages

File:‘/var/log/messages’

Size:367390Blocks:728IOBlock:4096regularfile

Device:ca02h/51714dInode:2093357Links:1

Access:(0644/-rw-r--r--)Uid:(0/root)Gid:(0/root)

Access:2018-01-2223:40:02.118066621+0800

Modify:2018-01-2223:40:01.118001621+0800

Change:2018-01-2223:40:01.118001621+0800

Birth:-

[root@test~]

[root@test~]GeneratedbyN

0000010:6574776

0000020:61726368206f70656e737461636b6c6farchopenstacklo

0000030:63616

0000040:31342

0000050:616

0000060:342

[root@test~]

```

批量修改文件名

用法:rename原字符串目标字符串文件

含义:

原字符串：将文件名需要替换的字符串；

目标字符串：将文件名中含有的原字符替换成目标字符串；

文件：指定要改变文件名的文件列

rename支持通配符：

?可替代单个字符

*可替代多个字符

[charset]可替代charset集中的任意单个字符

将所有已yum开头的文件的后缀名从.yumtx改为.txt

*

```

[root@test~]

[root@test~]*.txt

[root@test~]