A Technical I.T./DevOps Blog
Problem scenario
You run sudo bash start-yarn.sh but you receive this message:
ERROR: Attempting to operate on yarn resourcemanager as root
ERROR: but there is no YARN_RESOURCEMANAGER_USER defined. Aborting operation.
What should you do?
Solution
1. Modify start-yarn.sh. Underneath the last section of comments, place three lines with the following text:
YARN_RESOURCEMANAGER_USER=root
HADOOP_SECURE_DN_USER=yarn
YARN_NODEMANAGER_USER=root
2. Modify stop-yarn.sh.
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Problem scenario
You want to pass parameters to a function and assign the returned value to a parameter using the Go programming language. What should you do?
Solution
Prerequisite
This assumes that you have installed Golang; if you need assistance with this, see this posting.
Procedures
1.
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Problem scenario
You have Hadoop installed on a Linux machine. You want to install Apache Sqoop. What do you do?
Solution
Prerequisite
Verify one of these commands work:
hadoop dfs -ls
or
hdfs dfs ls
# If you need assistance installing Hadoop, see this posting.
Procedures
Download the installation media here: http://www.apache.org/dyn/closer.cgi/sqoop/
There are other sources.
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Problem scenario
You run sonar-scanner from the command prompt, but you receive an error. The error looks like one of the following:
“Task ‘-x’ does not exist. Please use ‘list’ task to see all available tasks”
“You must define the folowing mandatory properties for ‘Unknown’: sonar.projectKey, sonar.sources”
What should you do to get sonar-scanner to work?
Solution
Run the sonar-scanner command from a local directory where you have sonar-project.properties.
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Continue reading “How Do You Troubleshoot the sonar-scanner CLI Not Working?”
Problem scenario
You want to check the runtime duration of a section of Python code. How do you compute the amount of time something took in Python?
Solution
Write a program like this:
import datetime, time
t1 = datetime.datetime.now()
time.sleep(5) # replace this line with the section of code you want to time
t2 = datetime.datetime.now()
t3 = t2 – t1
print(“Time format is in hours:minutes:seconds:seconds_decimals”)
print(t3) …
Continue reading “How Do You Get Python to Compute How Long Something Took?”
Problem scenario
How do you install Apache Maven on any distribution of Linux?
Solution
Prerequisite: You must have Java installed for Maven to work after it is installed. It may make sense to install Java before you install Maven. Understand that mvn commands will not work until Java has been installed. If you need assistance install Java, see this posting.
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Problem scenario
You run “hadoop version” but you receive this message “Error: Could not find or load main class org.apache.hadoop.util.VersionInfo”. What do you do?
Possible Solution #1
Use “sudo ” before the “hadoop version” command.
Possible Solution #2
Use “sudo -i ” before the “hadoop version” command.
Possible Solution #3
Use a different user.
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Problem scenario
Hadoop is installed on Linux. But hadoop version and other hadoop commands are not working. What should you do?
Solution
Find the hadoop executable in a directory named bin. It is often “/usr/local/hadoop/bin/hadoop”. Ultimately you need to find the directory that houses this “bin.” has a subdirectory with “bin” and “hadoop” inside, run these two commands:
sudo find / -name hadoop -type f
whereis hadoop
Run these commands interactively where “/usr/local/hadoop” is the directory that is the parent of the subdirectory named “bin” that is the parent of the hadoop executable.
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Problem scenario
You want to find out what version of Splunk you are using. What command do you run?
Solution
Run this command: sudo /opt/splunk/bin/splunk version
If it does not work, run this command: sudo find / -name splunk -type f
Then run sudo /path/found/above/splunk/ version
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Continue reading “What Command Do You Use to Check if Splunk is Installed?”
Problem scenario
You are running a Go program. You see this message about “command-line-arguments”:
non-name m1[“foo”] on left side of :=
What should you do?
Possible Solution
Can you try to use “=” instead of “:=”? This may fix your problem.
The := is a variable declaration and an assignment. If your map has been declared,
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