top 10 learning management systems

cat file 内容显示到当前命令行中 cat -b file 输出表追行号，不忽略空行 cat -n file 输出表追行号，忽略空行2.head与tail head filename 显示一个文件的前几行，默认前10行 head -n 5 filename 查看文件内容前五行 tail filename 显示一个文件后几行，默认后10行 tail -n 5 filename 显示文件的最后5行tail -f filename 监控文件后10行内容3.less：分页浏览文件 当文件过长时使

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?????????

table Under the arc condition, when the _ weak points to the object is released, _ weak will be automatically set to nil. How can this be done in runtime? Maintain a weak table in the memory. /* OC Code */{ID _ weak obj1 = OBJ;}/* compiler simulation code */ID obj1; objc_initweak ( obj1, OBJ); objc_destroyweak ( obj1 ); As in the preceding code, the key is the object address OBJ, and the values is the _ weak address obj1. An object address can correspond to multiple _ weak variable addresses.

pointer. If statloc is not a null pointer, the termination status of the terminated process is stored in the memory unit pointed to by the pointer. If you do not care about the termination status, you can set the parameter to null. When a process calls wait, the caller is blocked until a sub-process is terminated. If no sub-process is called when the wait function is called, an error is returned immediately. Example: The following program replaces the sleep statement of the parent process after

.jpg" Width= "649" height= "439"/>View the PID of the user starting XRDP through the XRDP log.Then according to the PID, see the XRDP process started, as follows:Ps-ef |grep 1693650) this.width=650; "title=" clip_image010 "style=" border-right-width:0px;background-image:none; border-bottom-width:0px;padding-top:0px;padding-left:0px;margin:0px;padding-right:0px;border-top-width:0px; " Border= "0" alt= "clip_image010" src= "Http://s3.51cto.com/wyfs02/M00/6E/B3/wKiom1WCzpDS-LnWAAEh-n2jHh4741.jpg" W

Management of software packages for Linux learning Notes 1. RPM (RPM Package Manager) Format: for example, cvs.1.11.2-10. i386.rpm cvs: Software name 1.11.2: software package version number, including the main version number and minor version number i386: software running hardware platform rpm: File Extension www.2cto.com uninstall: rmp-e cvs [-- nodeps] if other

evangelist. spark Dean and chief expert of Asia Pacific Research Institute, dt android Span style= "font-family: the song Body;" > Soft and hard integrated source-level experts, English pronunciation magician, fitness enthusiasts. Public account:Dt_sparkContact email [email protected]Tel:18610086859qq:1740415547Number:18610086859Sina Weibo:ilovepainsLiaoliang's first Chinese Dream: Free for the whole society to cultivate thousands of outstanding big Data practitioners! Can be donated by

=" Wkiol1jscifw0qilaaabkmuxfc8272.png "/>Note: Incorrect string value: ' \xe7\x99\xbb\xe5\xbd\x95 ' for column ' LBL ' error when testing whether Svnadmin is running properlyWorkaround: Enter the Svnadmin database to execute the following statementALTER TABLE i18n MODIFY COLUMN lbl VARCHAR (255) CHARACTER SET UTF8 COLLATE utf8_unicode_ci not NULL; 4. using JsvnadminA), create a library650) this.width=650; "src=" Https://s1.51cto.com/wyfs02/M00/8F/09/wKioL1jSCuuB22kCAABcujcoWpM483.png "title=" 1

"expire_logs_days";+------------------+-------+| variable_name | Value |+------------------+-------+| Expire_logs_days | 7 |+------------------+-------+1 row in Set (0.00 sec)2. Slow query logMysql> Show variables like "slow_query_log%";+---------------------+--------------------------------+| variable_name | Value |+---------------------+--------------------------------+| Slow_query_log | On || Slow_query_log_file | /opt/mysql/data/mdb01-slow.log |+---------------------+-----------------------

to 0 is the command browser to delete the cookie. 6.1. Delete CookiesNote: When you delete a cookie, path must be the same, or it will not be deleted PackageGac.xdp.cookie;Importjava.io.IOException;Importjavax.servlet.ServletException;ImportJavax.servlet.http.Cookie;ImportJavax.servlet.http.HttpServlet;Importjavax.servlet.http.HttpServletRequest;ImportJavax.servlet.http.HttpServletResponse;/*** Delete Cookies*/ Public classCookieDemo02extendsHttpServlet { Public voiddoget (httpservletreque

, exit (0) is equivalent to return (0 ). If (a) Main executes a return statement without a return value, or (B) Main does not declare that the return type is integer, the termination status of the process is undefined. If the return type of the main function is integer and the return value is invisible when the main statement is executed to the last statement (return is not displayed or the exit function is called), the termination status of the previous version is undefined, the ISOC standard 1

BT source code learning experience (14th): client source code analysis (blocking Management in peer-to-peer connection) Author: Wolfenstein from our previous analysis we can see that when a peer-to-peer connection is established, exchange information through the handshake protocol, so that each connection has a connection object, and then there is a singledownload and upload corresponding to it. This time,

("company"); // string result = ID + "" + name + "" + company + "\ n"; // TV. settext (result); //} // If (Info = NULL) {// TV. settext ("duanjiefi"); //} else {// TV. settext ("liudandan"); // string name = info. getname (); // string Company = info. getcompany (); // int id = info. GETID (); // int salary = info. getsalary (); // TV. settext ("name:" + name + "\ n" + "Company:" + company + "\ n" + "Salary:" + salary ); ///} // string name = info. getname (); // string Company = info. getcompa

Execute permissions.Create directory: 777 minus the umask value for the created file permissions　　　　　　#umask: View the value of Umask　　　　　　#umaskNumber: Change the value of UmaskExit the current user, then login, the value of Umask will be updated to the original value, if you want to permanently exist, change the configuration fileIf the user name is the same as the basic group name:umask = 002If the user name is not the same as the base group name:umask = 022Administrator:umask = 022　　　　　　　　　

Inode record file attributes/permissions and other data, each inode size is fixed to 128bytes; Each file consumes only one inode, so the number of files the file system can build is related to the number of inode.7. The actual data of the block record file of the file, the block of the directory records the comparison table of the filename and its inode number.8, log (joural) file system will be more than a piece of record area, at any time to record the main activities of the file system, can

the background, can only be executed at the current login terminal, once you exit or close the terminal, the daemon will stopNohup Program #让程序在后台运行时脱离终端, that is, the terminal exits or shuts down, the daemon does not stopsystem Resources View:Vmstat [Refresh delay refresh Count] #监控系统资源Vmstat 1 3 #每一秒刷新一次, total 3 timesDMESG kernel check information when bootingDMESG | grep CPU #查看内核检查的CPU信息The free command to view memory usage statusfree [-b|-k|-m|-g]-B: Display-K:KB-M:MB-G:GB in bytesCat/pr

actions in topM: Sorts based on the size of the resident memory.P: Sorts according to the percentage size of CPU usage.T: Sort by Time/cumulative time.1: Can toggle display of all CPU usage statusQ: Exit TopTOP-BN1 output all information at once, static displaySAR command Monitors system Status4 SARIt can monitor all the resource status of the system, we mainly use it to monitor the network card.1 Viewing network card trafficSar-n DEVThis command prints the network card information that was rec

,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 ' LABEL ': set the volume label Example: Mke2fs-

: 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

; namespace threadexample { class timerexamplestate {Public int counter = 0; Public Timer tmr; } class App {Public static void Main () {timerexamplestate s = new timerexamplestate (); //Create proxy object TimerCallback, the agent will be called periodically TimerCallback timerdelegate = new TimerCallback (checkstatus); //Create a timer with a time interval of 1s Timer timer = New timer (timerdelegate, S,+, +); S.TMR = timer; //The main thread stops to wait for the