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Linux & Shell Scripting · Question Set
File Permissions, Users & Processes interview questions for placements and exams.
Questions
14
Included in this set
Subject
Linux & Shell Scripting
Explore more sets
Difficulty
Mixed
Level of this set
Go through each question and its explanation. Use this set as a focused practice pack for Linux & Shell Scripting.
By default, kill sends the SIGTERM signal, requesting the process to terminate gracefully. To forcefully stop a process, SIGKILL (-9) can be used, but it doesn’t allow cleanup operations.
kill 1234
top provides real-time system information including CPU, memory, and running processes. It helps administrators monitor system performance and identify resource-heavy applications.
top
Linux permissions are divided into read (r), write (w), and execute (x). Read allows viewing file contents, write allows modifications, and execute lets you run the file if it’s a program or script. Each type applies separately to owner, group, and others.
chown means 'change owner'. It allows an administrator to change the file owner and optionally its group. Only the root user or the file’s current owner can modify ownership permissions.
sudo chown ubuntu:devops app.log
Linux permission strings are divided into three sets — owner, group, and others. The second triplet (r-x) shows what permissions the file’s group has. Here, they can read and execute but not write.
useradd creates a new user account on the system. It can also specify home directories, groups, and shells. The adduser command is a user-friendly wrapper available in some Linux distributions.
sudo useradd -m -s /bin/bash devuser
passwd allows users or administrators to update account passwords securely. When executed, it prompts for the current password and then for the new one twice for confirmation.
passwd vipul
The ps command (process status) lists active processes along with their IDs, owners, and CPU usage. The -ef option shows all processes in full format, often used with grep to locate specific tasks.
ps -ef | grep nginx
renice changes the priority of an already running process. Lower values make a process more CPU-prioritized. System admins use it to ensure critical tasks get more compute resources than background jobs.
sudo renice -n -5 -p 3456
The sudo command executes a single command with superuser privileges, while su switches the current shell to another user (often root). sudo is safer because it logs activity and limits scope, whereas su grants a full privileged shell.
A process in Linux goes through several states — created, running, waiting, and terminated. When a process ends, it becomes a 'zombie' until its parent collects its exit status. Orphaned processes get adopted by the init system.
Appending an ampersand (&) after a command runs it in the background, freeing the terminal. To bring it back, use the fg command followed by its job number. You can check job numbers using jobs.
sleep 60 & jobs fg %1
You can add a user to a group using the usermod command with the -aG option. This ensures the user gets additional group permissions without removing existing ones. It’s common when granting sudo or docker access.
sudo usermod -aG sudo vipul
chmod stands for 'change mode' and is used to modify read, write, and execute permissions of files or directories. You can specify permissions using symbolic notation (rwx) or numeric codes (like 755 or 644).
chmod 755 script.sh
For complete preparation, combine this set with full subject-wise practice for Linux & Shell Scripting. You can also explore other subjects and sets from the links below.