learning management system examples

Tags: System/OPS LinuxReview the contents of the previous section:1. Scheduled execution of Task commands Crontab–e, crontab–l,crontab–r2. Job: Define a timed task to output Hello World to the/tmp/test.txt file every minuteCrontab–e*/1 * * * * echo ' Hello World ' >>/tmp/test.txtIn this section, let's take a look at file and directory management1. Computer operating system using directory organization files

read the time of the last Anacron execution in/var/spool/anacron/cron.daily.(2) compared with the current time, if two times difference is more than one day, perform cron.daily work.(3) Performing this work is only between 03:00-22:00.(4) The forced delay time is 5 minutes when performing the work, and then a random delay of 0-45 minutes(5) Use the Nice command to specify the default priority and use the Run-parts script to execute all executables in the/etc/cron.daily directory.Note: Anacron w

The System physical page is managed by the (page Frame number database) abbreviation PFN, which is actually an array, and each physical page corresponds to a PFN item.The address space of the process is managed through VAD (Virtual address destriptor). Each process has an AVL tree to hold these VAD nodes to record the addresses and attributes used.The memory address attribute of a process is divided into reserved and committed, which is the actual all

Boolean Insert (student students);/* * Delete student * */public abstract Boolean Delete (intSTUID) */* * UPDATE Student * */public Abstract boolean update (student students);/* * Find student * */public abstract student Search (int STUID);p ublic abstract Void Show (); ------------------Istudentdao Interface Implementation------------------------------Package Studentsystem;public class Studentdaodemo Implements Studentdao {private student student1[] = new student[100];p ublic void Start () {fo

the AT–C task IDAbove, only the most core information is displayed, you can see our command is LL.The time format of the AT command can beMinute??? At now + 5 minutes?? The task runs after 5 minutesHour????? At now + 1 hour????? The task runs after 1 hoursDays????? At now + 3 days????? The task runs after 3 daysWeeks???? At now + 2 weeks???? The task runs after two weeksFixed???? At midnight????????? Task runs at midnightFixed???? At 10:30pm?????????? Task at 10:30 in the eveningFixed???? At 23

"]==data["id"]) {Con[i]=data; Flag=true; Break; }} result.msg= "The modification failed, the customer needs to be modified does not exist"; if(flag) {Fs.writefilesync (Custompath,json.stringify (con),"Utf-8"); Result={code:0, msg:"Modified successfully"}} res.writehead (200,{' content-type ': ' Application/json;charset=utf-8; '}); Res.end (json.stringify (result)); }) return; } //If the requested address is not one of these, the prompt does not existRes.writehead (404,{' conten

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: Command history buffer size[Echo $HISTSIZE]The use of command history tips:!n: Executes the nth command in the command history!-n: Executes the last nth command in the command history!: Executes the previous command!string: The most recent command in the command history that starts with a specified string!$: Reference the last parameter of the previous commandShortcut key: esc+. or ALT +.Command aliases:Alias cmdalias= ' COMMAND [option] [argument] 'Ualias cmdalias: Canceling command aliasesCo

-I INPUT -s 192.168.10.9/24 -i eth0 -j ACCEPTThe meanings of each paragraph are:1说明要插入一条规则：iptables -I2.指定要操作的链 ： INPUT 3.指定源ip地址： -s 192.168.10.9/244.指定网卡： -i eth05.指定处理动作：-j ACCEPT-P Changing default rulesiptables -P OUTPUT DROPThe packet cannot be entered and the remote will be disconnectedAdd by Portiptables -A INPUT -s 192.168.10.9 -p tcp --sport 80 -d 192.168.11.9 --dport 80 -j REJECTThe meanings of each paragraph are:1.说明要插入一条规则：iptables -A2.指定要操作的链：INPUT3.指定源ip地址：-s 192.168.10.94.指定使用的

" - Represents a continuous time range. such as "0 5 * * 1-6 command", which represents the execution of commands from Monday to Saturday 5:0 A.M. */n Represents how often it is executed. Like "*/10 * * * * * * * * * * * * * * * * * * * * * * * * * * * command" time meaning TD valign= "Top" width= "196" > Execute command at 22:45 45 22 * * * command 0 17 * * * 1 command

environment in which there is a route, there is a signal controller, because the semaphore is an enumeration, do not instantiate here, directly in the controller associated with a semaphore can be.The test code is as follows://Package com.fylx.test; Public classtest{ Public Static voidMain (string[] args) {//TODO auto-generated Method StubString[] Lamps =NewString[] {"s2n","s2w","e2w","E2s","n2s","n2e","w2e","w2n","s2e","e2n","n2w","W2s" }; for(String lamp:lamps) {//according to the signal, in

,moosefs, MogileFS, Hdfs,gfs, GlusterfsTo create a file system:MKFS ( It is actually called according to the different file types, corresponding to the other formats of the/sbin under MKFS.EXT2,MKFS.EXT4, and so on-T)MKFS-T type DEVICE Example: Mkfs–t ext4/dev/sdb1 =mkfs.ext4/dev/sdb1MKE2FS ( Special Management tool for Ext Series file system):mke2fs-t {EXT2|EXT3|EXT4} DEVICE-B block:1024, 2048, 4096- l ' L

Commands for System Management classescommands for the System Management class : # shutdown (command) [option] ... Time -r : Restart h: shut down -c : Cancel restart or shutdown command time format: now Span style= "font-size:14pt" >

/s txcmp/s rxmcst/s12:10:01 AM Lo 0.00 0.00 0.00 0.00 0.00 0.00 0.0012:10:01 AM eth0 0.62 0.04 0.04 0.01 0.00 0.00 0.0012:10:01 AM eth1 0.59 0.01 0.04 0.00 0.00 0.00 0.00RXPCK/S indicates the number of packets received per second txpck/s Indicates the number of packets per second rxkb/s amount of data received per second txkb/s amount of data sent per second5 free View memory conditionTotal used free shared buffers cachedmem:1906900 274296 1632604 232 24268 111232-/+ buffers/cache:138796 176810

rootfs: Root file System /boot: System startup related files such as kernel, INITRD, and Grub (bootloader) /dev: device files Device files: block devices: Random access, data blocks Character Devices: Linear access, by character device number: Master device Good (major) and secondary device number (minor) /etc: Config file / Home: The user's home directory, each user's home directory usually