Devops QS Flashcards
What is DEVOPS
DEVEOPS IS A SOFTWARE DEVOLOPMENT METHODOLOGY THAT COMBINES PROCESS AND TECHNOLOGY AND PROVIDES REALBILTY TO SOFTWARE DELIVERY
What is open source software?
open souce software is a software were the code is able to seen and is acessible to the publice where they can change and deliver it as they see fit
What are the differences between Linux vs Windows?
linux is a free open source software that is 4 times more efficient has more stability
windows is not free its less efficient and uses graphical use interface
Explain Linux file system hierarchy
its a reference to the linus directory structue where all the file and folders reside under the parent folder
What are the differences between CentOS and RedHat?
centosos is more stable operating system it does not have support
redhat less stable but it requires payment to be supported
What are the differences between CentOS 6 vs 7 vs 8?
centos 6 ,7, and 8 are the end of their life cycles. centos 6 used ext4 filesystem , centos 7 used ifs filesystem , centos 8 used
centos 9 is up to date
uses the xfs,btfs filesytem
Explain Linux File Permissions
is set of permissions that determine who are given to access system to be able to read write and execute file
What is CLI and GUI?
CLI is the command line interface which is used in linus operating system to have commands outputs
GUI is the graphical user interface which is used by windows
How do you create a directory in Linux?
you create directory in linux by using the mkdir command
how do you create an empty file in linus
create an empty file by using the touch command
how do you check the current working directory
you check by using the pwd command
if a user knows the command but does not know how to use it, how can she get help
you can get help by using the man command which stands for manual followed by the command it will give you a descriptive information on how to use it or you can use google
what does / represent
it represent the parent folder where all the files and folders are under
if a user need to read the content of the file on screen , and set the line numbers what command can he use
the read the content he or she can use the cat command with -n see the numbers with the information printed
If a user needs to find out the number of lines and words in a file, what command can he/she use?
he/she can use the wc command
On a file using “vi” command, how can a user search for a word?
you can use the slash followed by the word
How to set numbers, using “vi” command mode?
in vi command you first press the escape button for the command then type the colon then by set number
What command do you use to find a string in a file?
you can use the grep command
What command do you use to find a file?
you can use the find command
How to find a file in the system, owned by a specific user?
you use the find command follwed -user
How to delete 100 lines in a file, from cli?
to delete 100
you will use d#d which deletes multiple lines
What command would you use to copy specific columns from a file?
the command you would use the awk or the cut command
What is a Linux shell? What are the popular shells in Linux?
linux shell is program where input command gives the operating system to peform
some populare shells zsh bash shell ksh korn
What is the difference between ‘standard error’ and ‘standard output’?
‘standard output’ is the terminal screen where the response are shown from the command
standard error the default error output devicce which is used to write all system error messages
How to rename a file/folder in Linux?
to rename a file you can use the mv command followed by source and then destination
By default which folder has the home directory of the users added to the system?
/home folder of users in the system
Which command will show the current kernel running in your system?
the uname command will show the current kernel of system
There is a file under /etc folder that will show the current release of the operating system, what is the name of the file?
os-release”
Explain /proc folder
the proc folder is the virtual file stystem for running os and applications provides information about the system’s state and kernel
Explain /mnt folder
subdirectory of the root directory in Linux and other Unix-like operating systems that serves as a temporary mount point for file systems.
used to mount storage devices like USB drives, CDROMs, and floppy disks.
Explain /etc folder
central location for system configuration files and directories
Explain /root folder
the top-level directory in a computer’s file system. It’s the starting point for organizing all files and folders, and is often reserved for essential system files
Explain /home folder
a personal storage space for a user’s files, configurations, and data
Where do you find log files in a CentOS machine?
find in /var/log directory
What are some of common log files you work with?
apache logs
applications logs
system logs
What is an inode?
file data structure that stores information about any Linux file except its name and data.
What types of file systems do you know?
ext4 red hat os 6
xfs red hat os7
btrfs rehat os9
ntfs windows fs
apfs apple fs
What is a swap space? How do you check for swap usage
the secondary memory in storage can use the free command to check for usage
What is load average in Linux?
a metric that measures the average system load over a certain period. I
How do you check load average?
you can use the uptime command
How much load average is too much for your system?
consistently higher than the number of CPU cores
How do you find a processes using most CPU?
using the top command displays all running processes
What command do you use to check for disk usage?
df command to check
A client is complaining that she/he can’t ssh to a server, how would you troubleshoot this issue?
first i would replicate problem to make if the problem was real
then i would check the server is running
A client is complaining that she/he can’t connect to a web server, how would you troubleshoot this issue?
- Replicate the problem (Ask for a screenshot) (Example: wrong domain)
- Check Digital Ocean and see if VM is running
- SSH to VM
- Check for SELinux (Disable)
- Check if Web Server is running (systemctl status httpd)
- Firewall
Clients > Cloud Firewall > Linux{ Linux Firewall > Web Server
WordPress is complaining about database connectivity issue, how would you troubleshoot?
- Replicate the problem (Ask for a screenshot) ( mysql -u wpuser -p XXXXXX )
- Check Digital Ocean and see if VM is running
- SSH to VM
- Check for SELinux (Disable)
- Check if MySQL is running (systemctl status mysqld)
- Wrong Username?
- Wrong Password?
