Linux Quiz Section

ls -a

ls -lh

cp file1 file2

mv file1 file2

rm -f file1

mkdir directory1

rmdir directory1
rm -rf directory1

cat file1

echo "Hello, World!"

echo "Hello, World!" > file1

echo "Hello, World!" >> file1

echo "Hello, World!" | wc -c

echo "Hello, World!" | wc -w

echo "Hello, World!" | wc -l

echo "Hello, World!" | grep "World"

cat file1 | grep "and"

cat file1 | grep -v "and"

cat file1 | grep -i "AND"

cat file1 | grep -n "and"

cat file1 | grep -c "and"

cat file1 | grep -c "and" | wc -l

cat file1 | grep -c "and" | wc -w

cat file1 | grep -c "and" | wc -c

echo "Hello, World!" | sed 's/World/Universe/'

echo "Hello, World!" | tr '[:lower:]' '[:upper:]'

echo "Hello, World!" | cut -d' ' -f2

uptime

free -h

df -h

top

ps aux

netstat -tulnp

ss -tulnp

systemctl status sshd
systemctl start sshd
systemctl stop sshd
systemctl restart sshd

systemctl enable sshd
systemctl disable sshd

systemctl reload sshd

crontab -l
crontab -e
crontab -r

scp file1 user@host:/path
scp user@host:/path/file1 .

rsync -avz file1 user@host:/path
rsync -avz user@host:/path/file1 .

scp -r directory1 user@host:/path
scp -r user@host:/path/directory1 .

rsync -avz directory1 user@host:/path
rsync -avz user@host:/path/directory1 .

scp -r directory1 user@host:/path
rsync -avz directory1 user@host:/path

sudo mount /dev/sdb1 /mnt
sudo umount /mnt
sudo mount -t ext4 /dev/sdb1 /mnt
sudo umount /mnt
sudo mount -t cifs //server/share /winmnt -o user=username
sudo mount -o loop file.iso /mnt

zip -r archive.zip directory1
unzip archive.zip
tar -czvf archive.tar.gz directory1
tar -xzvf archive.tar.gz

chmod 755 file1
chown user:group file2
chown -R user:group directory1
chgrp group file3
umask 022

chmod 777 file1
chmod -R 755 directory1
chmod u+x file2

useradd user1
userdel user1
groupadd group1
groupdel group1

usermod -aG group1 user1
deluser user1 group1
passwd user1

journalctl
dmesg
tail -f /var/log/syslog

journalctl -u sshd
journalctl -u sshd -f
journalctl -u sshd --since "2021-01-01"

dmesg | grep -i error
journalctl -p err
tail -f /var/log/syslog | grep -i error

journalctl -u sshd -n 10
journalctl -u sshd --since "1 hour ago"
journalctl -u sshd --since "1 hour ago" --until "now"

journalctl -u sshd --since "1 hour ago" --until "now" | grep -i error
journalctl -u sshd --since "1 hour ago" --until "now" | grep -i error | wc -l
journalctl -u sshd --since "1 hour ago" --until "now" | grep -i error | wc -l | awk '{print $1}'

journalctl -u sshd --since "1 hour ago" --until "now" | grep -i error | wc -l | awk '{print $1}'
journalctl -u sshd --since "1 hour ago" --until "now" | grep -i error | wc -l | awk '{print $1}' | sort
journalctl -u sshd --since "1 hour ago" --until "now" | grep -i error | wc -l | awk '{print $1}' | sort -n

ssh-keygen -t rsa -b 4096 -f ~/.ssh/id_rsa
ssh-copy-id user@host
ssh -i ~/.ssh/id_rsa user@host

ip addr show
ip route show
ip link show

ip addr add
ip route add
ip link set

ip addr del
ip route del
ip link del

ip addr show | grep -i inet
ip route show | grep -i default
ip link show | grep -i state

ping 10.56.37.133
nmap -sP 10.56.37.0/24

netstat -tulnp
ss -tulnp

netstat -tulnp | grep -i 22
ss -tulnp | grep -i 22

telnet 192.168.1.1 53
curl http://192.168.1.1

traceroute 192.168.1.1
mtr google.com

dig google.com
nslookup google.com

host google.com
whois google.com

mtr --tcp --port 80 google.com
mtr 8.8.8.8

nmap -sS example.com
nmap -sT example.com

nmap -sU example.com
nmap -sA example.com

nmap -sV example.com
nmap -O example.com

nmap -sC example.com
nmap -sV -sC example.com

nmap -sU -p 53 example.com
nmap -sU -p 53 --script dns-zone-transfer example.com

curl -I http://example.com
curl -L http://example.com

curl -X POST -d "username=admin&password=admin" http://example.com/login
curl -X PUT -d "username=admin&password=admin" http://example.com/login

curl -X DELETE http://example.com/user/1
curl -X PATCH -d "username=admin" http://example.com/user/1

curl -X OPTIONS http://example.com
curl -X HEAD http://example.com

tcpdump -i eth0
tcpdump -i eth0 -n
tcpdump -i eth0 -nn

tcpdump -i eth0 -c 10
tcpdump -i eth0 -w capture.pcap
tcpdump -i eth0 -r capture.pcap

tcpdump -i eth0 -A
tcpdump -i eth0 -X
tcpdump -i eth0 -XX

tcpdump -i eth0 -s 0
tcpdump -i eth0 -s 128
tcpdump -i eth0 -s 256

tcpdump -i eth0 -w capture.pcap -C 10
tcpdump -i eth0 -w capture.pcap -W 10
tcpdump -i eth0 -w capture.pcap -G 10

tcpdump -i eth0 -w capture.pcap -Z root
tcpdump -i eth0 -w capture.pcap -G 10 -Z root

openssl s_client -connect example.com:443
openssl s_client -connect example.com:443 -showcerts

openssl s_client -connect example.com:443 -servername example.com
openssl s_client -connect example.com:443 -servername example.com -showcerts

mtr -P 53 google.com
mtr -P 53 -T google.com

mtr --split google.com
mtr --report --report-cycles 10 google.com