popular learning management systems

Http://blog.sina.com.cn/s/blog_65373f1401019dtz.htmlLinux Kernel Learning notes-5 memory management1. Related Data structuresallocating memory in the kernel tends to be more restrictive than user space, such as the inability to sleep in many cases in the kernel, and the failure to handle memory allocations as easily as user space. The kernel uses both page and zone data structures to manage memory:Page 1.1The kernel takes physical pages as the basic u

reading and writing test, if the release two times-c-c, will test read and write (Read-write), will be slow ~-L: Can be followed by a header name (label)-j: Originally MKE2FS is EXT2, add-j, will join Journal and become EXT3.7. fsck to check the file system for errors8. Badblocks Check if the hard drive or floppy disk sector has bad track9. Mount,unmount Disk mount and dismountAttention:1) A single file system should not be repeatedly mounted in different mount points (directories);2) A single

, 32768fragmentspergroup8192inodespergroupsuperblockbackups storedonblocks:32768,98304,163840,229376,294912,819200,884736, 1605632 is writing inode table: complete creatingjournal (32768blocks): complete writing superblocksandfilesystemaccountinginformation: Complete Thisfilesystemwill beautomaticallycheckedevery29mountsor180days,whichever comesfirst.usetune2fs-cor-itooverride. [[emailprotected]~]# 650) this.width=650; "src=" Http://s3.51cto.com/wyfs02/M00/72/F0/wKioL1XwS8XSERK2AAOGqYLMqrs004.jp

, because it is like built-in functions, how to handle the compiler to say, leave the function, the value disappears) formal parameters (when the parameter is passed, more cases are defined as automatic variables or register variables)Global variables:External variables (variables defined outside the outer function, other files can be used after the extern declaration, disappear at the end of the program)Static external variables (other files may not be used, disappear at the end of the program)

scaling are achievable, and redis clusters make things a lot easier as long as you're willing to spend time and effort on it.SummaryOver the past few years, there have been many programs and sites using Redis, without a doubt that Redis can already be used in real production. However, some tools are not mature enough, especially for some security and usability-related tools. For Redis clusters, we hope to see their implementations soon, which should provide a handle to some of the existing

can hold is 16GB, which is consistent with the file restriction table results. However, this method is not applicable when the block size is 2KB or 4KB, because the block larger than 2KB will be limited by the EXT2 file system itself, and the calculation results and the restriction table.(3) Super blockwhere this block records information about the entire file system, the main records are:Block and the total amount of innode;The number of unused and used innode/block;The size of block and innod

/****************************************************************//* Learning is a collaborative and shared style!/* Author:atlas Email:[email protected]* * Reprint Please indicate the source of this article:* http://blog.csdn.net/wdzxl198/article/details/9178099/****************************************************************/Previous Period content review:C + + Memory Management

OS automatically mounts each file system defined in this file when it is initiallyThe format of each line:Devices to mount:/dev/sda5Mount point:/mnt/testFile system type: ext3Mount option: DefaultsSwitching frequency (make a full backup every few days): 0File system detection order (only root can be 1): 0Practice:1, create a 5G partition, the file system is ext3, the volume label is MyData, the block size is 1024, the reserved management space for th

Article Title: Task Management for linux Learning. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source. : Add an symbol at the end of the command to indicate the background task, for ex

Webuid=608 (web) gid=608 (web) groups=608 (web)Infrequently used parameters-B Specify the base directory-C Specify Note information-D Specify the user's home directory-E Expiration Time-F Disable Time7. Chage commandThis command is used for password aging management. It can modify the expiration date of the account and password[Email protected] ~]# chageUsage: chage [options] LoginOptions:-D,--lastday Last date set the most recent password setting ti

the parameters in the /etc/login.defs file, so it is valid for everyone, the user encryption mode that has been created is not changed, but the modifications change, the new user uses the modified encryption algorithm, and the re-login is still validThe second $ after is salt (salt): Can be abstracted as the role of spices, is the same password, add salt generated by the random number based on the avalanche effect, the resulting ciphertext is not the same, so that if someone else's password cip

variables, placed in the CPU register, C + + is not necessary, because it is like built-in functions, how to handle the compiler to say, leave the function, the value disappears) formal parameters (when the parameter is passed, more cases are defined as automatic variables or register variables)Global variables:External variables (variables defined outside the outer function, other files can be used after the extern declaration, disappear at the end of the program)Static external variables (oth

= +, effective uid= +lienhua34:demo$su# ChownRoot tsys#chmodu+s tsys#ls-L Tsys-rwsrwxr-x1Root Lienhua347358October the at:Panax Notoginsengtsys# exitexitlienhua34:demo$./tsys./printuidsreal UID= +, effective uid=0During the execution of the above, we set the owner of the Tsys file to Superuser root and set the user ID bit. Thus, when executing the Tsys file, the process has a valid user ID of 0 (that is, root). The child process that calls the system function to execute the Printuids file inher

format expansion without uninstallation)The xfsgrowfs/dev/vg1/lv1 must be mounted at the time of the command operation.df-h View, you can see that the size has been enlarged to 300M.The logical volume space cannot be larger than the volume group space, and the volume group needs to be expanded before the logical volume can be scaled up after the volume group space has been consumed by the logical volume.vgextend vg1/dev/sdb3 adds/dev/sdb3 into VG1vgdisplay View Volume group information, you can

18.3 "Linux learning is not difficult"File System Management (3): InLinuxcreating a file system in the systemuse the MKFS command to create various file systems on a partition. the MKFS command itself does not perform the work of establishing the file system, but rather calls the relevant program to execute it. The file system here is to be specified, such as xfs

Linux Learning notes a Disk Management common commandLinux system, everything is a file, disk is a special block device files.Common hard-disk interface types The same port: IDE, SCSI Serial Port: Sata,sas command rules for disk device file device files : IDE: Device name/dev/hda,/dev/hdb .... (at the end of A, b ... Represents a different IDE hard drive) SCSI: The device is n

controlling SYSTEMD systems and service management.Systemctl Start Service Name sshd # # #开启服务Stop .... # # #关闭服务Restart .... # # #重启服务Reload .... # # #重新加在服务配置Status .... # # #查看 Service StatusEnable .... # # #设定服务开机启动Disable .... # # #禁止服务开机启动List-dependencies (Note using tab) # # #查看服务依赖关系List-units # # #查看当前运行的所有服务List-unit-files # # #查看服务的开机启动情况Set-default Multi-user.target # # #开机不启动图形 StartX can then turn on the graphicsSet-default Graphical.t

update-alternatives--Management soft Connect/Word linked (Symbolic links) Command format update-alternatives [Options] Command Detailed description Update-alternatives can be created, deleted, repaired, soft-connected, and can display information about existing soft links, all of which constitute the Debian alternative system (alternatives systems). Many times we will install differ

at this point.-L: The system can also use the file system header name (label) to import a row mount, in addition to the device file name (for example,/DEV/HDC6) cookbook. It's best to canceled a unique name for your file system!-O: You can attach some additional parameters after mounting! For example, account number, password, read and Write permissions: RO, rw: Mount file system becomes just read (RO) ring erasable (rw) Async, Sync: This file system uses synchronous write (sync) ring Asynchron

commands for managing a Linux system. For Linux systems, whether the CPU, memory, disk drives, keyboards, mice, or users are all files, the Linux System Management command is the core of its normal operation, similar to DOS commands. There are two types of Linux commands in the system: built-in shell commands and Linux commands.Second, Linux system Management co