CONTINUAL INTEGRATION

Problem scenario
You try to copy a file. It fails with "Permission denied." What should you do?

Possible Solutions
1. Are the permissions of the destination folder/directory permissive? Is you user supposed to be able to write to the destination folder/directory?

2. Is there an open file in the destination directory? Sometimes this can cause unexpected problems (e.g., with Git Bash).

3. Are you sure the location is correct? In today's world with public and private clouds, Git Bash, Git CMD, PowerShell, DOS prompts, Putty terminals, VNC sessions, Remote Desktop Sessions, web UI terminals, servers can become easily confused with each other

At the time of writing, we suggest these troubleshooting steps for many I.T. tasks. Some of these will not apply to every problem. But if you do not know where to begin, this can help you with "DevOps block."

1. Find the word "error" in the logs. Look at a log with vi (e.g., copy the log to a location where it will not be continually written to). Open the copy with vi. Run this command:
:set ignorecase

Search for the word "error"

2. Reboot the server and try again.

3. Find one server or program that works, see how it is different from the one that fails.

4. Start over from the beginning (redeploy).

5. Find what changed since it was last working. If it never worked, try to deploy it on a different distribution of Linux.

6. If the problem is reproducible, try to isolate the problem. A back-to-basics approach can involve reducing problems to atomic parts. From there you can diagnose an underlying component having a problem and thus find a solution.

Problem scenario
You want to rapidly create hundreds of lines of text for a file. You want to do some testing and you need a file you can delete. You also want to use the seq keyword.

Solution
Here is a program that uses the seq keyword:

#!/bin/bash
COUNTER=100

for varnum in `seq $COUNTER`
do
  date >> goodfile
  echo $varnum >> goodfile
done

Some people recommend not using the seq keyword. An alternative way of writing the above is this:

#!/bin/bash

for varnum in {1..100}
do
  date >> goodfile
  echo $varnum >> goodfile
done

You notice the {1..100} is more terse with no COUNTER variable assignment.