Linux
Processes, permissions, services, system behavior, and troubleshooting.
What is the difference between a hard link and a soft link?
A hard link points to the same inode, while a soft link points to the file path.
What is the difference between a process and a thread?
A process has its own memory space, while threads share memory inside the same process.
How do Linux file permissions work?
Permissions define read, write, and execute access for owner, group, and others.
What is systemctl used for?
systemctl is used to manage services and systemd units.
What is the difference between top and htop?
Both show running processes, but htop is more interactive and user-friendly.
What is load average in Linux?
Load average shows how many processes are actively running or waiting for CPU or uninterruptible resources.
What is iowait in Linux?
iowait is CPU time spent waiting for disk or other I/O operations to complete.
What is the difference between SIGTERM and SIGKILL?
SIGTERM asks a process to stop gracefully, while SIGKILL forces it to stop immediately.
What is a zombie process?
A zombie process is a finished process whose exit status has not yet been collected by its parent.
What is the Linux kernel?
The kernel is the core of the operating system that manages hardware and processes.
What is a shell?
A shell is a command-line interface to interact with the system.
What is a filesystem?
A filesystem organizes how data is stored and accessed on disk.
What is the root directory?
The root directory is the top-level directory in Linux, represented by '/'.
What is the home directory?
It is the personal directory for a user.
What does the cat command do?
cat displays file contents.
What is grep used for?
grep searches for patterns in text.
What is the find command?
find searches for files and directories.
What does the ps command do?
ps shows running processes.
What is the kill command?
kill sends signals to processes.
What does df do?
df shows disk usage.
What does du do?
du shows file and directory size.
What is chmod?
chmod changes file permissions.
What is chown?
chown changes file ownership.
What is SSH?
SSH is a secure protocol for remote access.
How do you check CPU usage in Linux?
Using top, htop, or vmstat.
How do you check memory usage?
Using free or top.
How do you monitor disk I/O?
Using iostat or iotop.
What is netstat?
netstat shows network connections.
What is ss command?
ss is a faster alternative to netstat.
What is systemd?
systemd is a system and service manager.
What is journalctl?
journalctl reads system logs.
What is cron?
cron schedules tasks.
What is crontab?
crontab stores scheduled jobs.
What are environment variables?
They store configuration values for processes.
What is PATH?
PATH defines where executables are searched.
How do you create a symbolic link?
Using ln -s.
What does chmod 777 mean?
It gives full permissions to everyone.
What is sudo?
sudo runs commands with elevated privileges.
Where are logs stored in Linux?
Usually in /var/log.