linux practice exam

Article title: Xen virtual machine practice: how to create a snapshot using Linux commands. 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. A vm snapshot is a good function that ca

patiently ...). ）3) Unzip the installation package and copy the files to the/opt/dotnet directory4) Create a soft link file named dotnet in the/usr/local/bin directory to point to the/opt/dotnet/dotnet file, and the soft link is understood as a shortcut2. Create a. Net Core applicationmkdir HwappCD Hwappdotnet NewCommand Simple explanation1) Create a directory named Hwapp2) Enter the directory3) Execute the dotnet new command to create a. Net Core project3. Restore dependent libraries Run prog

need to add a $ symbol here, the same as a, B.Pls Input One Num:2[Email protected] ~]# read-t 5-p "Pls input" num: "a BPls Input 2 Num:1 Above for I read "with the old boy learn Linux Yun Koriyuki Shell programming Combat" This book when the note, if there are any copyright issues, please contact the message.This article is from the "shayatou_1990" blog, make sure to keep this source http://shayatou1990.blog.51cto.com/12806916/1918020"Learn

; /* Buffer for Ipc_stat, Ipc_set */ unsigned short *array; /* Array for GETALL, SETALL */ struct seminfo *__buf; /* Buffer for Ipc_info (linux-specific) */};Practice: setvalunion mysemun{ int val; Value for setval// struct semid_ds *buf; Buffer for Ipc_stat, ipc_set// unsigned short *array; Array for GETALL, setall// st

Linux practice engineer study Note 5: Use the disk quota or modify the/etc/fstab file to enable the quota for each file system-add the option usrquota The default system kernel supports quota. Mount-o usrquota, maid/dev/sdb1/mnt/d1 or Mount-o remount, usrquota, kgquota/ You can also modify the/etc/fstab file to enable the quota of each file system-add the options usrquota Example: Set LABEL =/home ext3 defa

TSD.specific data; with the key-value Implementation, a thread creates a key, another thread creates it, But not pointing to the same fast memory, they point to their own data,This is thread-specific data.In the code above, even Sleeep (2), thread 1 's data is not affected by thread 2 's data, because it is thread-private. When the thread exits, it is destroyed 2 times because two threads were created. where Tid is the thread's id,str is passed to the Thread_routine parameter, you can see tha

Linux multithreading practice (6) Use Posix condition variables to solve producer and consumer problems In the previous article, we have already discussed how to use semaphores to solve the producer and consumer problems. Under what circumstances should we introduce conditional variables? Assume that there is a shared resource sum, and the associated mutex is lock_s. assume that the sum operation of each th

) this.width=650; "Src=" https://s3.51cto.com/wyfs02/M00/06/59/wKiom1m2kkCwIeL5AAMgwH9Tc7Y055.jpg-wh_500x0-wm_ 3-wmp_4-s_3415807704.jpg "style=" Float:none; "title=" 2017-09-11_18-08-59.jpg "alt=" Wkiom1m2kkcwiel5aamgwh9tc7y055.jpg-wh_50 "/>650) this.width=650; "Src=" https://s5.51cto.com/wyfs02/M02/A5/09/wKioL1m2khqgYFRzAAK4x4B_4WQ733.jpg-wh_500x0-wm_ 3-wmp_4-s_1350431586.jpg "style=" Float:none; "title=" 2017-09-11_18-16-16.jpg "alt=" wkiol1m2khqgyfrzaak4x4b_ 4wq733.jpg-wh_50 "/>650) this.widt

of the subscription. A nice day! Go Shopping with me topic message.Mtqq_mosquittoMtqq_mosquittoIn addition to the Android side can send messages, of course, can also receive. Open another terminal and publish a message with the shopping topicmosquitto_pub -t shopping -m "Sorry,I have no time."You can see the Logcat in Android and show that you have received the corresponding message.Mtqq_mosquittoMtqq_mosquittoandroid Project DownloadHttps://github.com/djstava/MqttClientAndroidReference documen

the same semantics. ).Open rules for Named pipes1) Read Open FIFOO_nonblock Disable (blocked): block until a corresponding process has opened the FIFO for writeO_nonblock Enable(non-blocking): Return to success immediatelyExample 1: Blocking, read-only open int main () { int fd = open ("FIFO", o_rdonly); if (fd = =-1) err_exit ("FIFO open Error"); cout Example 2: Read-only, non-blocking open int main () { int fd = open ("FIFO", o_rdonly| O_nonblock); if (fd = =-1) e

-1The difference between wait and waitpid: 1. Before a child process terminates, wait causes its callers to block, and Waitpid has a selection that allows the caller to not block. 2.waitpid does not wait for the first terminated child process: It has several selections that control the specific process it waits for. the 3.wait function is equivalent to a special case of the Waitpid function.Waitpid ( -1, status, 0);Zombie Process (if not wait ...) When a child process finishes running, the assoc

All for reference only, welcome anyone to discuss[Page] 151 [position] my_rwl.c [Type] Code error[Description] From the book to see __LINE__, is an underscore, but in fact, the built-in macro is the front and back of each of the two sliding lines, namely _ _line_ _[Page] 195 [position] studyuid.c [Type] Code error[Description] The header file for Strerror () is string.h and needs to be added before code can run[Page] 251 [position] ctrlpocess.c [Type] Code error[description] Read function declar

];then./etc/bashrcfi[[emailprotected][1]~]# #注释掉后重新登录即可. Attach the CP command related parameters:-r,-r,--recursivecopydirectoriesrecursively-- reflink[=when]controlclone/cowcopies. Seebelow.--remove-destinationremove eachexistingdestinationfilebefore attemptingtoopenit (Contrastwith --force) --sparse=WHEN controlcreationofsparsefiles.Seebelow. --strip-trailing-slashesremoveanytrailingslashes fromeachsource argument-f,-- force ifanexistingdestinationfilecannotbe opened,removeitandtry again (re

(Result,"%.3s%.3s%3d%.2d:%.2d:%.2d%d\n", Wday_name[timeptr-Tm_wday], mon_name[timeptr-Tm_mon], timeptr->tm_mday, timeptr->Tm_hour, Timeptr->tm_min, timeptr->Tm_sec,1900+ timeptr->tm_year); return result;}The doubt is lifted, and you can see that CTime returns a static local char array.System call Lseek Change Open file location:Handling Errors in system callsDetermine the type of error errno.Display error message Perror:The ls-a option lists hidden files:How to write LS:Stat gets file attribute

) The initial group of ADMINCW is Caiwu3) Adminjs Initial Group is Jishu 4) Tom is an additional user of the Shengchan group5) Harry is an additional user of the CAIW group6) Leo is an additional user of the Jishu group7) Create a new administrative user, the user does not belong to the above mentioned three departments650) this.width=650; "Src=" https://s4.51cto.com/wyfs02/M00/08/1F/wKiom1nblRiRWtq5AADorr1M3Fg844.png-wh_500x0-wm_ 3-wmp_4-s_2873800465.png "title=" screenshot from 2017-10-09 20-3

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

://s3.51cto.com/wyfs02/M02/72/5F/wKiom1XhxM2Se05mAACuJ0RWhoU423.jpg "/>6. Add User bash, Testbash, basher, and Nologin user (Nologin user's shell is/sbin/nologin), then find out/etc/ A row in the passwd file that has the same user name as its shell name650) this.width=650; "src=" http://s3.51cto.com/wyfs02/M00/72/5B/wKioL1XhxurS81jMAACo3vS6Y-o251.jpg "/>7 , display the default shell and UID for root, CentOS, or User1 users on the current system "Please create these users beforehand, if not prese

of a process marked as dead_process. *//* the Ut_session and Ut_tv fields must is the same size when compiled 32-and 64-bit. This allows data files and the shared memory to be shared between 32-and 64-bit applications. */#ifdef __wordsize_time64_compat32 int32_t ut_session;/* session ID, used for windowing. */struct {int32_t tv_sec;/* Seconds. */int32_t tv_usec;/* microseconds. */} ut_tv;/* time entry was made. */#else Long int ut_session;/* session ID, used for windowing. */struct Time

:/usr/local/bin:/usr/local/sbin:~/bashExport PATHDeclare-i sum=0For I in {1..100}; DoLet remainder= $I%3If [$REMAINDER-eq 0]; ThenLet sum= $SUM + $IFiDoneecho "$SUM"Exercise Three:Write a scriptShows all default shell-bash users and default shell-/sbin/nologin users on the current system, respectively.and statistics of the total number of Shell users, showing the results are as follows:Bash,3users,they Are:root,redhat,gentooNologin,2users,they are:bin,ftp#!/bin/bash#program:#显示当前shell下面的用户#histo

1. is echo an internal command or an external command? What is its role? How do i show "The Year is 2016.Today is 10yue 26" for two lines?With the type command, ECHO is an internal command:[[Email protected] ~]# type echoEcho is a shell builtinecho function: Displays the input content directly.Echo-e "The year is 2016. \ n today is 7. "[Email protected] ~]# ECHO-E "The year is 2016. \ntoday is 7. "The year is 2016.Today is 7.2. is printf an internal command or an external command? What is its ro