Linux Technical Interview QA with Practical Sessions

                            LINUX Basic Course Outline

Here are topic wise Linux System Administrator Interview Questions …

Interview Questions on topic User Administration in Linux

• What the fields of /etc/passwd file?
• How to create a user with specifying a primary/Secondary grp?
• How can you create a user without useradd command?
• What is the default permission on user's home directory?
• What is the difference between .bash_profile and .bashrc?
• What is the command to create a user with a pre defined uid, shell and home directory?
• How to change primary group for any user?
• If I delete a user, does it's home directory gets deleted? If not then what is the command to delete the home directory of user along with the user
• Name any 3 files which are automatically created inside any user's home directory when a user is added.
• What is the command to view all the currently logged in users?
• What is the command to change and view the expiry date for any user?
• What are the details you get with finger command?
• How can you give a normal user all the root level privileges?
• Name any 3 groups of which root is a member by default
• How can you give sudo access to any user without asking him to provide passord every time he runs a command?
• Why should I use visudo command instead of directly editing the file with vi or any other editor?
• Default permission of file and Directory ?
• How to view the User's login and logout details ?
• How to check Primary and Secondary Group of One User ?
• How to lock & unlock the User Account ?

Interview Questions on topic permissions in Linux

• What is the difference between SUID and SGID?
• What is Sticky Bit permission?
• What is umask?
• What is the default umask value for useradd command and where is it defined?
• Will you be able to cd into a directory with only read permission?
• What is -R argument used for along with chmod command?
• How can you restrict a normal as well as root user from making any changes as well as deleting any file?
• What is the difference between small t and capital T when applying sticky bit permission?
• List out few of the differences between Softlink and Hardlink?
• What is the difference between umask and ulimit ?

Interview Questions on topic LVM in LINUX

• How many volume groups can be created in Linux ?
• Is it possible to increase the logical volume on fly ?
• How to reduce the logical volume ? is it possible to reduce on fly ?
• How to increase the logical volume?
• How to do you scan the new LUN or disk for LVM  physical volume ?
• How to scan disks for existing volume group ?
• How to scan a logical volume from existing volume group?
• How to stop the logical volume ? or deactivate the logical volume ?
• How to activated the logical volume which in deactivated state ?
• How to disable the volume group ? or Deactivate the volume group ?
• How to enable the volume group ? or Activate the volume group ?
• How do you find that what are the disks are used for  logical volume mirroring ?
• How to list the imported volume groups ?
• How to list the available logical volumes on the system?
• How to list the available physical volumes in LVM?
• How to see the detailed volume group information ?

Interview Questions on topic Linux Boot Process

• Explain booting process ?
• Define BIOS, MBR?
• Explain GRUB and how it differs from latest GRUB2?
• How would you define initramfs and what is its function in the Linux booting process?
• What is the one new feature of RHEL 7?
• What is systemd? And tell few features of systemd which makes it differs from other OS.
• Overview of Systemd in RHEL 7?
• List few features of Systemd? And tell few features of systemd which makes it differs from other OS.
• Booting process of RHEL 7?
• When it is required to boot the Linux box in to rescue mode and how we can boot it on rescue mode?
• What is the command to change the runlevel in RHEL 7? and also to view what targets are available you can issue the list-units option with the type target?
• Rescue mode in RHEL7 & how can we boot into Rescue mode?
• What is basic difference between Rescue & Emergency Mode?
• How can we recover MBR if it gets corrupted?
• Suppose someone accidently deleted the mount binary i.e. (/bin/mount) and rebooted the Linux Box, then how would recover your box from this situation?

Interview Questions on topic SSH in LINUX

• What is the default port & configuration file of SSH Server ?
• How to change the default ssh port in linux ?
• What is the configuration file of ssh client ?
• How to disable the root login in linux server ?
• How to allow only specific users to ssh your linux server ?
• How to enable debugging in ssh command ?
• What is the difference between ssh & Telnet ?
• What is use of sshpass command in linux ?
• What is the use of scp command ?
• What is the use of blowfish options in scp command ?
• How to limit the bandwidth used by scp command ?
• How to enable passwordless ssh authentication in Linux ?
• How to check SSH server’s Version ?
• How to Copy the file “server.txt” from the local machine to a remote host using port 2751 in /opt folder.

Technical Interview QA on Process Management

• What is a prcoess and whats the command to list all the process?
• How to use custom properties while running a ps command?
• What is PID & PPID ? Example with an example?
• What is a nice value & how can we set it for a process?
• What is 'D Uninterruptible sleep mode?
• What is Z and paging Stat process stats?