linux practice exam

the number of tasks is huge, you can imagine the number of clicks on a popular website. But for long-time tasks, such as a Telnet connection request, the thread pool's advantages are not obvious. Because the Telnet session time is much larger than the thread's creation time. (2) for performance -demanding applications, such as requiring the server to respond quickly to customer requests.(3) Receive a large number of bursts of requests, but do not allow the server to generate a large number of t

another terminal, modify the user permission of Dir directory in turn)5) Create a new file in Dir directory Tom.txt, the owner is Tom, the group is the Group1,/test directory permissions of 7776) New user rose, switch to Rose User, verify the Rose User's rwx permissions to Tom.txt (open another terminal, modify tom.txt others permissions to match the verification process)7) Add rose to the group1 group and, under the Rose user, verify the rwx permissions of the rose user to Tom.txt (open anothe

depth option to enable the Find command to do so. One reason for this is that when you use the Find command to back up the file system to tape, you want to back up all the files first, and then back up the files in the subdirectories.The instance 1:find command starts at the root of the file system and looks for a file named Con.file.Command:Find/-name "CON. FILE "-depth-printDescriptionIt will first match all the files and then go to the subdirectory to find12. Using the Mount option:You can u

-r ' s#.* ([A-Z ]$) #\1# ' C method 13 [[emailprotected]shell]$echo $a |awk-F/ ' {print $NF} ' C method 14 [[emailprotected]shell]$echo $a |awk ' {gsub (". * *", "", $ );p Rint} ' C method 15 [[emailprotected]shell]$echo $a |awk ' {split ($0,array, "/");p Rintarray[3]} ' C method 16 [[emailprotected]shell]$echo $a |awk ' {split ($0,array, "a/b/");p rintarray[2]} ' C method 17 [[emailprotected]shell]$echo$ a|awk ' {sub (/[^c]+/, "");p Rint} ' C method 18 [[emailprotected]shell]$echo $a |awk ' {

It has not been developed with Eclipse in Linux for several years, and it was developed with Eclipse in CentOS 7 a few years ago, as if it were a newer version. Recently, a project called for the card to be sent under CentOS, after the installation of ECLIPSE-CDT, the establishment of the project found that no C + + project tips.Query the webpage, there is a webpage http://blog.sciencenet.cn/blog-655584-547162.html, feel also need to install ECLIPSE-P

Switch from normal user to root user:You can use Su or Su-:The most essential difference between the SU command and the Su-command is that the former simply switches the root identity, but the shell environment is still the shell of the normal user, and the user and the shell environment are switched to root. The PATH environment variable error does not occur unless you switch the shell environment. After the SU switch to the root user, PWD, found that the working directory is still the normal u

summarize the detailed usage method of the task plan (at, crontab) on Linux system;Task Scheduling on Linux:The task plan is divided into:Perform a task at a time in the future and achieve the target command: at BatchPerform a task periodically in the next time, crontabe-Mail Service:Protocol: SMTP: Simple Mail Transfer Protocol/var/spool/mail/usernameDefault mail directory for logged-on usersPOP3: Post Office ProtocolIMAP4: Internet Access ProtocolMa

First, homework (exercise) content:1. Summarize the detailed usage method of the task plan (at, crontab) on Linux system;2, every Monday to Saturday 3:20 A.M., run the CP command to archive the/etc/directory, storage location is/BACKUPS/ETC-YYYY-MM-DD;3, every Sunday 2:30 A.M., run the CP command to backup the/etc/fstab file, the storage location is/BACKUP/FSTAB-YYYY-MM-DD-HH-MM-SS;4, every night 12 o'clock, get all the lines in the/proc/meminfo file

1. Summarize the detailed usage method of the task plan (at, crontab) on Linux system; at: Executes the command at the specified timeAt [option] ... TimeTime:(1) Absolute timeHH:MM,Mmdd[cc]yy, Mm/dd/[cc]yy, dd.mm.[cc]yy or [cc]yy-mm-ddTomorrow(2) Relative timenow+ #UNITMinute, hour, day, week(3) Blur timeMidnightNoonTeatimeCommon options:-Q queue:at Job queue;-f/path/from/somefile: Reads the job to be run from the specified file;-L: View

First, Linux operation and maintenance exercises and answers1. Display the lines in the/etc/passwd file that end with bash650) this.width=650; "src=" http://s3.51cto.com/wyfs02/M00/72/93/wKiom1Xm0FjwCMnCAAB3I_JQ3vU396.jpg "title=" 1.png " alt= "Wkiom1xm0fjwcmncaab3i_jq3vu396.jpg"/>2. display the two-digit or three-digit number in the/etc/passwd file650) this.width=650; "src=" http://s3.51cto.com/wyfs02/M02/72/90/wKioL1Xm0-nAshFBAAI6jr6BBHQ791.jpg "tit

, single-digit segment, 10-segment, 100-199-segment, 200-249-segment, 250-255-segment[[Email protected]_server home]# ifconfig | Egrep "\650) this.width=650; "src=" Http://s3.51cto.com/wyfs02/M01/72/51/wKioL1XgimTx5PjCAAHHzsHS2iA054.jpg "title=" the tenth question " alt= "Wkiol1xgimtx5pjcaahhzshs2ia054.jpg"/>There are still some problems, such as the number in the MAC address is not crawled out.Extensions: fetch the IP address of the ifconfig. The feature is that the first cannot be 0 for a rang

increases concurrency, but the creation and scheduling of such threads is done by the kernel , so the overhead of such threads is large ( but generally less than the process overhead)3. n:m[maps N User-level threads to M kernel-level threads, requires n>=m, contemporary POSIX threads (that is, the threading model currently used by Linux)] The N:M threading model provides level two control that maps a user thread to a system's scheduler to implement a

sequencing: sort took 2.0581 seconds sort took 2.2358 seconds sort took 1.7775 seconds(Attached-Host configuration: Dual core four thread (Intel (R) core (TM) i3-2350m CPU @ 2.30GHz))Summary: You can see that although there is a merge step after sorting (merge), multi-threaded sequencing (computationally intensive tasks) is better than single-threaded sequencing (in the case of multicore CPUs), and it takes a minimum of time to sort the arrays using four threads under the four thread of the CPU

resources it consumes are not released, that is, there is no real termination. only when the Pthread_join () function returns does the created thread release the system resources that it occupies . In the case of detached attributes, the system resources that it occupies are released immediately at the end of a thread. one thing to note here is that if you set the Detach property of a thread, and the thread runs very fast, it is likely to terminate before the Pthread_create () function returns,

Background: The client server is mounted with a Trojan horse for mining (bitcoin).This cleanup is done through the Linux Basic command. The principle is also relatively simple, through the PS command to view the server exception process, and then through the lsof command to locate the files accessed by the process, find the exception file deletion, and finally to ensure foolproof, can be found by the Find command in the recent time the server generate

Sed-i ' ni\x ' test.file means adding X content to the front of the nth line in the Test.file fileSed-i ' na\x ' test.file means adding X content to the nth line in the Test.file fileSed-i '/m/i\x ' test.file means adding X content to the front of the line that matches the M string in the Test.file fileSed-i '/m/a\x ' test.file means adding X content after the line that matches the M string in the Test.file file-I means in front, front-A indicates after, behindFor example, add 123456789 to the f

-project.com/sources/libgdiplus/libgdiplus-3.8.0.tar.gz.bz2Tar xjvf libgdiplus-3.8.0.tar.gz.bz2CD libgdiplus-3.8.0. \configure--PREFIX=\USRMakeMake install4, CD \CD usr\localwget http://download.mono-project.com/sources/mono/mono-3.10.0.tar.gz.bz2Tar xjvf mono-3.10.0.tar.gz.bz2CD mono-3.10.0. \configure--PREFIX=\USRMakeMake install5.CD \CD usr\localwget http://www.linuxdot.net/down/jexus-5.6.3.tar.gzTAR-ZXVF jexus-5.6.3.tar.gzCD jexus-5.6.3./installCD \Usr/jexus/jws startwget URL address may not

detailed steps and practice of writing Linux makefile files 1.makefile OverviewThe IDE will help you to write makefile files in Windows environment, but in Unix you have to write your own makefile, write Makefile, and explain from one side whether a person has the ability to complete a large project. Because, makefile is related to the compilation rules of the whole project. A project in the source file d

, press "10G" to position the cursor to line 10th.Then press "O" in lowercase, another line below the current line, and enter insert modeFinally press RETURN to general mode on the keyboard, and then enter ": R/root/1.txt" carriage return8. When you are editing a file, you can still run the Linux command without exiting the fileColumn: I'm editing a file, but at this point I want to see the contents of the "/root/1.txt" file, but I don't want to quit