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250 Linux Scenario Based Interview

Q1: How would you find all files larger than 100MB in a directory and its subdirectories?

find /path/to/directory -type f -size +100M

  • -type f: Finds only files.
  • -size +100M: Specifies files larger than 100MB.

Q3: How do you recursively delete all .log files in a directory?

find /path/to/directory -name "*.log" -type f -delete
  • -name "*.log” : Matches files with .log extension.
  • -type f: Targets only files.
  • -delete: Deletes the files found.

Q4: How do you create a tarball of /var/log and compress it with gzip?

tar -czvf logs.tar.gz /var/log
  • -c: Creates a tarball.
  • -z: Compresses using gzip.
  • -v: Verbose output.
  • -f logs.tar.gz: Specifies the tarball file name.

Q5: Test specific port availability:

nc -zv <server_ip> <port>

Q6: How do you permanently assign an IP address in Linux?

Edit the network configuration file:

vi /etc/sysconfig/network-scripts/ifcfg-eth0

IPADDR=192.168.1.100
NETMASK=255.255.255.0
GATEWAY=192.168.1.1

sudo systemctl restart network

Q7: How do you identify a process consuming high CPU?

ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%cpu | head

Q8: How do you monitor disk I/O in real-time?

iostat -x 2

  • -x: Shows extended statistics.
  • 2: Refreshes every 2 seconds.

Q9: How do you kill a process by its name?

pkill <process_name>


pgrep <process_name>

Q11: How do you set up a basic firewall rule to allow SSH traffic?

sudo ufw allow ssh

sudo ufw status

How do you check for unauthorized access attempts on your server?

sudo cat /var/log/auth.log | grep "Failed password"

Write a script to check if a file exists and display its permissions.

#!/bin/
FILE=$1
if [ -e "$FILE" ]; then
 echo "File exists."
 ls -l "$FILE" | awk '{print $1}'
else
 echo "File does not exist."
fi

./script.sh filename

How would you write a script to archive logs older than 7 days?

#!/bin/
find /var/log -type f -mtime +7 -exec tar -rvf old_logs.tar {} \; -exec rm {} \;
  • -mtime +7: Finds files older than 7 days.
  • -exec: Executes tar to archive and rm to delete

How do you add a new user with a specific home directory?

sudo useradd -m -d /custom/home/username username
  • -m: Creates the home directory.
  • -d: Specifies the custom directory.

How do you change the default shell for a user?

sudo usermod -s /bin/ username

cat /etc/passwd | grep username

Inspect running processes:

ps aux --sort=-%cpu | head

# Check I/O operations:
iostat -x 2

# Verify memory usage:
free -m

How do you extend a mounted LVM partition?

sudo lvextend -L +10G /dev/mapper/vol_group-lv_name

sudo resize2fs /dev/mapper/vol_group-lv_name

How do you find the top 10 largest files in a directory?

find /path/to/dir -type f -exec du -h {} + | sort -rh | head -n 10

How do you back up a directory using rsync?

rsync -av /source/directory /destination/director
  • -a: Archive mode.
  • -v: Verbose output

How do you restore files from a tar backup?

Use logrotate:

sudo logrotate /etc/logrotate.conf --force

How do you view the last 50 lines of a log file?

tail -n 50 /var/log/syslog

How do you check the groups a user belongs to?

groups username