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Shilpa Nair Shares Her Interview Experience on RedHat Linux Package Management
Shilpa Nair has just graduated in the year 2015. She went to apply for Trainee position in a National News Television located in Noida, Delhi. When she was in the last year of graduation and searching for help on her assignments she came across Tecmint. Since then she has been visiting Tecmint regularly.
Linux Interview Questions on RPM
All the questions and answers are rewritten based upon the memory of Shilpa Nair.
“Hi friends! I am Shilpa Nair from Delhi. I have completed my graduation very recently and was hunting for a Trainee role soon after my degree. I have developed a passion for UNIX since my early days in the collage and I was looking for a role that suits me and satisfies my soul. I was asked a lots of questions and most of them were basic questions related to RedHat Package Management.”
Here are the questions, that I was asked and their corresponding answers. I am posting only those questions that are related to RedHat GNU/Linux Package Management, as they were mainly asked.
1. How will you find if a package is installed or not? Say you have to find if ‘nano’ is installed or not, what will you do?
Answer : To find the package nano, weather installed or not, we can use rpm command with the option -q is for query and -a stands for all the installed packages.
# rpm -qa nano OR # rpm -qa | grep -i nano nano-2.3.1-10.el7.x86_64Also the package name must be complete, an incomplete package name will return the prompt without printing anything which means that package (incomplete package name) is not installed. It can be understood easily by the example below:
We generally substitute vim command with vi. But if we find package vi/vim we will get no result on the standard output.
# vi # vimHowever we can clearly see that the package is installed by firing vi/vim command. Here is culprit is incomplete file name. If we are not sure of the exact file-name we can use wildcard as:
# rpm -qa vim* vim-minimal-7.4.160-1.el7.x86_64This way we can find information about any package, if installed or not.
2. How will you install a package XYZ using rpm?
Answer : We can install any package (*.rpm) using rpm command a shown below, here options -i (install), -v (verbose or display additional information) and -h (print hash mark during package installation).
# rpm -ivh peazip-1.11-1.el6.rf.x86_64.rpm Preparing... ################################# [100%] Updating / installing... 1:peazip-1.11-1.el6.rf ################################# [100%]If upgrading a package from earlier version -U switch should be used, option -v and -h follows to make sure we get a verbose output along with hash Mark, that makes it readable.
3. You have installed a package (say httpd) and now you want to see all the files and directories installed and created by the above package. What will you do?
Answer : We can list all the files (Linux treat everything as file including directories) installed by the package httpd using options -l (List all the files) and -q (is for query).
# rpm -ql httpd /etc/httpd /etc/httpd/conf /etc/httpd/conf.d ...
4. You are supposed to remove a package say postfix. What will you do?
Answer : First we need to know postfix was installed by what package. Find the package name that installed postfix using options -e erase/uninstall a package) and –v (verbose output).
# rpm -qa postfix* postfix-2.10.1-6.el7.x86_64and then remove postfix as:
# rpm -ev postfix-2.10.1-6.el7.x86_64 Preparing packages... postfix-2:3.0.1-2.fc22.x86_64
5. Get detailed information about an installed package, means information like Version, Release, Install Date, Size, Summary and a brief description.
Answer : We can get detailed information about an installed package by using option -qa with rpm followed by package name.
For example to find details of package openssh, all I need to do is:
# rpm -qi openssh [root@tecmint tecmint]# rpm -qi openssh Name : openssh Version : 6.8p1 Release : 5.fc22 Architecture: x86_64 Install Date: Thursday 28 May 2015 12:34:50 PM IST Group : Applications/Internet Size : 1542057 License : BSD ....
6. You are not sure about what are the configuration files provided by a specific package say httpd. How will you find list of all the configuration files provided by httpd and their location.
Answer : We need to run option -c followed by package name with rpm command and it will list the name of all the configuration file and their location.
# rpm -qc httpd /etc/httpd/conf.d/autoindex.conf /etc/httpd/conf.d/userdir.conf /etc/httpd/conf.d/welcome.conf /etc/httpd/conf.modules.d/00-base.conf /etc/httpd/conf/httpd.conf /etc/sysconfig/httpdSimilarly we can list all the associated document files as:
# rpm -qd httpd /usr/share/doc/httpd/ABOUT_APACHE /usr/share/doc/httpd/CHANGES /usr/share/doc/httpd/LICENSE ...also, we can list the associated License file as:
# rpm -qL openssh /usr/share/licenses/openssh/LICENCENot to mention that the option -d and option -L in the above command stands for ‘documents‘ and ‘License‘, respectively.
7. You came across a configuration file located at ‘/usr/share/alsa/cards/AACI.conf’ and you are not sure this configuration file is associated with what package. How will you find out the parent package name?
Answer : When a package is installed, the relevant information gets stored in the database. So it is easy to trace what provides the above package using option -qf (-f query packages owning files).
# rpm -qf /usr/share/alsa/cards/AACI.conf alsa-lib-1.0.28-2.el7.x86_64Similarly we can find (what provides) information about any sub-packge, document files and License files.
8. How will you find list of recently installed software’s using rpm?
Answer : As said earlier, everything being installed is logged in database. So it is not difficult to query the rpm database and find the list of recently installed software’s.
We can do this by running the below commands using option –last (prints the most recent installed software’s).
# rpm -qa --lastThe above command will print all the packages installed in a order such that, the last installed software appears at the top.
If our concern is to find out specific package, we can grep that package (say sqlite) from the list, simply as:
# rpm -qa --last | grep -i sqlite sqlite-3.8.10.2-1.fc22.x86_64 Thursday 18 June 2015 05:05:43 PM ISTWe can also get a list of 10 most recently installed software simply as:
# rpm -qa --last | headWe can refine the result to output a more custom result simply as:
# rpm -qa --last | head -n 2In the above command -n represents number followed by a numeric value. The above command prints a list of 2 most recent installed software.
9. Before installing a package, you are supposed to check its dependencies. What will you do?
Answer : To check the dependencies of a rpm package (XYZ.rpm), we can use switches -q (query package), -p (query a package file) and -R (Requires / List packages on which this package depends i.e., dependencies).
# rpm -qpR gedit-3.16.1-1.fc22.i686.rpm /bin/sh /usr/bin/env glib2(x86-32) >= 2.40.0 gsettings-desktop-schemas gtk3(x86-32) >= 3.16 gtksourceview3(x86-32) >= 3.16 gvfs libX11.so.6 ...
10. Is rpm a front-end Package Management Tool?
Answer : No! rpm is a back-end package management for RPM based Linux Distribution.
YUM which stands for Yellowdog Updater Modified is the front-end for rpm. YUM automates the overall process of resolving dependencies and everything else.
Very recently DNF (Dandified YUM) replaced YUM in Fedora 22. Though YUM is still available to be used in RHEL and CentOS, we can install dnf and use it alongside of YUM. DNF is said to have a lots of improvement over YUM.
Good to know, you keep yourself updated. Lets move to the front-end part.
11. How will you list all the enabled repolist on a system.
Answer : We can list all the enabled repos on a system simply using following commands.
# yum repolist or # dnf repolist Last metadata expiration check performed 0:30:03 ago on Mon Jun 22 16:50:00 2015. repo id repo name status *fedora Fedora 22 - x86_64 44,762 ozonos Repository for Ozon OS 61 *updates Fedora 22 - x86_64 - UpdatesThe above command will only list those repos that are enabled. If we need to list all the repos, enabled or not, we can do.
# yum repolist all or # dnf repolist all Last metadata expiration check performed 0:29:45 ago on Mon Jun 22 16:50:00 2015. repo id repo name status *fedora Fedora 22 - x86_64 enabled: 44,762 fedora-debuginfo Fedora 22 - x86_64 - Debug disabled fedora-source Fedora 22 - Source disabled ozonos Repository for Ozon OS enabled: 61 *updates Fedora 22 - x86_64 - Updates enabled: 5,018 updates-debuginfo Fedora 22 - x86_64 - Updates - Debug
12. How will you list all the available and installed packages on a system?
Answer : To list all the available packages on a system, we can do:
# yum list available or # dnf list available ast metadata expiration check performed 0:34:09 ago on Mon Jun 22 16:50:00 2015. Available Packages 0ad.x86_64 0.0.18-1.fc22 fedora 0ad-data.noarch 0.0.18-1.fc22 fedora 0install.x86_64 2.6.1-2.fc21 fedora 0xFFFF.x86_64 0.3.9-11.fc22 fedora 2048-cli.x86_64 0.9-4.git20141214.723738c.fc22 fedora 2048-cli-nocurses.x86_64 0.9-4.git20141214.723738c.fc22 fedora ....To list all the installed Packages on a system, we can do.
# yum list installed or # dnf list installed Last metadata expiration check performed 0:34:30 ago on Mon Jun 22 16:50:00 2015. Installed Packages GeoIP.x86_64 1.6.5-1.fc22 @System GeoIP-GeoLite-data.noarch 2015.05-1.fc22 @System NetworkManager.x86_64 1:1.0.2-1.fc22 @System NetworkManager-libnm.x86_64 1:1.0.2-1.fc22 @System aajohan-comfortaa-fonts.noarch 2.004-4.fc22 @System ....To list all the available and installed packages on a system, we can do.
# yum list or # dnf list Last metadata expiration check performed 0:32:56 ago on Mon Jun 22 16:50:00 2015. Installed Packages GeoIP.x86_64 1.6.5-1.fc22 @System GeoIP-GeoLite-data.noarch 2015.05-1.fc22 @System NetworkManager.x86_64 1:1.0.2-1.fc22 @System NetworkManager-libnm.x86_64 1:1.0.2-1.fc22 @System aajohan-comfortaa-fonts.noarch 2.004-4.fc22 @System acl.x86_64 2.2.52-7.fc22 @System ....
13. How will you install and update a package and a group of packages separately on a system using YUM/DNF?
Answer : To Install a package (say nano), we can do,
# yum install nanoTo Install a Group of Package (say Haskell), we can do.
# yum groupinstall 'haskell'To update a package (say nano), we can do.
# yum update nanoTo update a Group of Package (say Haskell), we can do.
# yum groupupdate 'haskell'
14. How will you SYNC all the installed packages on a system to stable release?
Answer : We can sync all the packages on a system (say CentOS or Fedora) to stable release as,
# yum distro-sync [On CentOS/RHEL] or # dnf distro-sync [On Fedora 20 Onwards]
Seems you have done a good homework before coming for the interview,Good!. Before proceeding further I just want to ask one more question.
15. Are you familiar with YUM local repository? Have you tried making a Local YUM repository? Let me know in brief what you will do to create a local YUM repo.
Answer : First I would like to Thank you Sir for appreciation. Coming to question, I must admit that I am quiet familiar with Local YUM repositories and I have already implemented it for testing purpose in my local machine.
To set up Local YUM repository, we need to install the below three packages as:
yum install deltarpm python-deltarpm createrepo
Create a directory (say /home/$USER/rpm) and copy all the RPMs from RedHat/CentOS DVD to that folder.
mkdir /home/$USER/rpm
cp /path/to/rpm/on/DVD/*.rpm /home/$USER/rpm
Create base repository headers as.
createrepo -v /home/$USER/rpm
Create the .repo file (say abc.repo) at the location /etc/yum.repos.d simply as:
cd /etc/yum.repos.d && cat << EOF > abc.repo [local-installation]name=yum-local baseurl=file:///home/$USER/rpm enabled=1 gpgcheck=0 EOF
Important: Make sure to remove $USER with user_name.
That’s all we need to do to create a Local YUM repository. We can now install applications from here, that is relatively fast, secure and most important don’t need an Internet connection.
Okay! It was nice interviewing you. I am done. I am going to suggest your name to HR. You are a young and brilliant candidate we would like to have in our organization. If you have any question you may ask me.
Me: Sir, it was really a very nice interview and I feel very lucky today, to have cracked the interview..
Obviously it didn’t end here. I asked a lots of questions like the project they are handling. What would be my role and responsibility and blah..blah..blah
Friends, by the time all these were documented I have been called for HR round which is 3 days from now. Hope I do my best there as well. All your blessings will count.
Thankyou friends and Tecmint for taking time and documenting my experience. Mates I believe Tecmint is doing some really extra-ordinary which must be praised. When we share ours experience with other, other get to know many things from us and we get to know our mistakes.
It enhances our confidence level. If you have given any such interview recently, don’t keep it to yourself. Spread it! Let all of us know that. You may use the below form to share your experience with us.
via: http://www.tecmint.com/linux-rpm-package-management-interview-questions/
作者：Avishek Kumar 译者：译者ID 校对：校对者ID