10 Interview Questions and Answers on Linux Commands

Linux is an open-source operating system that has gained popularity over the years. Linux commands are essential for system administration, development, and daily operations. If you are preparing for a technical interview, understanding core Linux commands is crucial. This article provides 10 common Linux command interview questions with detailed answers to help you succeed.

What is the command to create a new file in Linux?

The command to create a new file in Linux is touch. This versatile command allows users to create empty files instantly.

touch filename.txt

The touch command can also update timestamps of existing files and create multiple files simultaneously:

touch file1.txt file2.txt file3.txt

What is the command to display system information in Linux?

Several commands display system information depending on your specific needs:

What is the command to display running processes in Linux?

The ps command displays currently running processes. Two commonly used variations are:

ps aux
ps -ef

For real-time process monitoring, use top or htop:

top
htop

What is the command to display disk space usage?

The df command shows disk space usage for mounted filesystems:

df -h

This displays sizes in human-readable format (GB, MB, KB). Other useful options:

• df -T Shows filesystem types

• df -i Shows inode usage

• du -sh /path Shows directory size

What is the command to display memory usage?

The free command shows system memory usage:

free -h

              total        used        free      shared  buff/cache   available
Mem:           7.7G        2.1G        3.2G        256M        2.4G        5.1G
Swap:          2.0G          0B        2.0G

What is the command to display network information?

The modern ip command provides comprehensive network information:

ip addr show
ip link show
ip route show

Legacy ifconfig command (if available):

ifconfig

What is the command to display the routing table?

Use ip route to view the routing table:

ip route
ip route show default

Alternative commands:

route -n
netstat -rn

What is the command to display process status?

To check the status of a specific process, use:

ps -p <PID>
ps -p 1234

To monitor process status continuously:

watch -n 1 "ps -p <PID>"

What is the command to display the process tree?

The pstree command shows processes in a tree format, displaying parent-child relationships:

pstree
pstree -p
pstree <PID>

Alternative using ps:

ps -ef --forest

What is the command to check system uptime?

The uptime command displays system uptime, load averages, and logged-in users:

uptime

 15:30:25 up 5 days,  2:45,  3 users,  load average: 0.15, 0.25, 0.20

For detailed boot information:

who -b
last reboot

Conclusion

Mastering these fundamental Linux commands is essential for system administration and technical interviews. Each command offers various options and flags that provide detailed system information. Practice these commands regularly and explore their manual pages using man command_name to deepen your understanding and become proficient in Linux system management.