Linux memory Dd,rpm,yum, software Installation

Job One:

1) Add a 15G SCSI hard disk before opening the Linux system

2) Turn on the system, right click on the desktop, open the terminal

3) for the newly added hard disk partition, a primary partition size of 5G, the remaining space to the extended partition, on the extended partition divided 1 logical partitions, the size of 5G

4) format primary partition as EXT3 system

5) Set logical partition to swap partition

6) enable the Swap partition for the previous step

7) View the status of the swap partition

Job Two: Free command to view memory

Organizing the role of buffer and cache

Buffer buffers are something that has not been "written" to disk.

The cache cache is something that is stored after "read" from disk

Cache: Caching is a small but high-speed memory that sits between the CPU and the main memory. Because the CPU speed is much higher than the main memory, the CPU accesses the data directly from the memory to wait for a certain period of time, the cache holds the CPU just used or recycled part of the data, when the CPU re-use the part of the data can be directly called from the cache, which reduces the CPU waiting time, Improve the efficiency of the system. The cache is also divided into one-level cache (L1 cache) and level two cache (L2 cache), L1 cache is integrated within the CPU, L2 cache is usually soldered to the motherboard, and is now integrated into the CPU, with a common capacity of 256KB or 512KB L2 Cache.

Buffer: An area where data is transferred between devices that are not synchronized or that have different priority levels. Through buffers, you can reduce the number of waits between processes, so that when you read data from a slow device, the operating process of a fast device is uninterrupted. The buffers and caches shown in the free command are memory: buffer: The memory of the buffer cache is the read-write buffer for the block device, closer to the storage device, or directly to disk's buffer. Cache: As the memory of page cache, the cache of the file system is the buffer of memories if the cache value is large, it indicates that the cache has many files. If frequently accessed files can be cache, then the disk read IO must be very small

To put it simply, the central role of buffer is to cushion and mitigate shocks. For example, you have to write 100 times a second hard disk, the system is a big shock, wasting a lot of time busy processing began to write and finish writing these two things. Use a buffer to temporarily save, turn into every 10 seconds to write the hard disk, the impact on the system is very small, writing efficiency is high, the days are cool. Greatly eased the impact.
　　
The central role of the cache is to speed up access. For example, you have a very complex calculation done, the next time you have to use the results, the results will be a good place to hold, next time don't forget. Speed up data access.

Calculate Real Memory utilization
(used/total) *100% = (829/1837) *100% =44%

Job Three: DD command to test hard drive speed

Job Four: Find a process named Init and force it to kill

Job Five: RPM command

1) Mount the disc file to the/media directory

2) Enter the packages directory under the/media directory

3) View all RPM packages installed on the system

4) Check to see if the system is installing DHCP packages

5) Install the DHCP package

6) View information for DHCP packages

7) View all files included in the DHCP package

8) See which package generated the/bin/ls file

9) Uninstalling the DHCP package

Job Six: Yum command

1) Customizing the Yum repository: Createrepo

2) Customizing the repo file

3) Install the HTTPD package using the Yum command

4) Uninstalling the HTTPD package: yum–y Remove software name

5) Install the component ' KDE desktop ' using yum: Yum–y Groupinstall Component Name

6) Master using Yum to remove components ' KDE Desktop ': Yum–y groupremove Component Name

7) Master purge Yum cache: Yum Clean all

8) Use Yum to find packages: Yum Search package Name

Job Seven: source code installation Python

Linux memory Dd,rpm,yum, software Installation