A Technical I.T./DevOps Blog
Problem scenario
You are using the tar command. You are getting an error when you try to compress a file. This is the message:
“tar (child): Cannot execute remote shell: No such file or directory
Cannot open: Input/output error
tar (child): Error is not recoverable: exiting now
tar: Child returned status 2
tar: Error is not recoverable: exiting now”
What should you do?
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Problem scenario
You are using Ubuntu or a Debian distribution of Linux. You log in and see this (the message of the day):
6 packages can be updated.
6 updates are security updates.
You then run this: sudo apt-get -y upgrade
But it does not work. You see this message:
“0 upgraded, 0 newly installed, 0 to remove and 3 not upgraded.”
What can you do to update your Linux server and not be warned about packages that can be updated?
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Problem scenario
You want a script to run whenever a user logs in (e.g., when a sudoer uses “su jdoe”, you want a script to run before you assume the jdoe user). You are using Linux SUSE or Ubuntu or a Debian distribution. You found that having a script in /etc/profile.d/ does not work. What should you do?
Solution
To have a script automatically run for a given user,
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Continue reading “How Do You Get a Script to Execute Every Time You Log in as the User in Linux?”
Problem scenario
You have a Debian or Ubuntu Linux server. You want to install a trial version of Splunk. What should you do?
Solution
1. Sign up for an account to get the installation media: https://www.splunk.com/en_us/download.html
2. Click on “Linux”
3. Obtain the .deb file.
4. Put the .deb file on the Linux server.
5. Install the file.
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Continue reading “How Do You Install Splunk on a Debian/Ubuntu Linux Server?”
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. Underneath the last section of comments,
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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. Create a file called c.go with this as the content:
package main
import “fmt”
// Function that accepts parameters and returns an integer value:
func multiply(x int, …
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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