ls – List directory contents
cd – Change directory
pwd – Print working directory
mkdir – Create directories
rmdir – Remove empty directories
rm – Remove files or directories
cp – Copy files and directories
mv – Move or rename files
touch – Create a new empty file
cat – Concatenate and display file content
more – View file content page by page
less – View file content with backward navigation
head – Display the beginning of a file
tail – Display the end of a file
echo – Display a line of text
df – Report filesystem disk space usage
du – Estimate file space usage
chmod – Change file permissions
chown – Change file ownership
whoami – Display the current user

ps – Report a snapshot of current processes
top – Display tasks and system performance in real-time
kill – Terminate processes
killall – Kill processes by name
ping – Send ICMP echo request to test network connectivity
wget – Download files from the internet
curl – Transfer data to/from a server
grep – Search text using patterns
find – Search for files and directories
locate – Find files by name
tar – Archive files using tarballs
gzip – Compress files
gunzip – Decompress .gz files
zip – Compress files into a zip archive
unzip – Extract files from a zip archive
scp – Securely copy files between hosts
rsync – Synchronize files and directories
df -h – Show disk space usage in human-readable format
du -sh – Display directory size
nano – Open a text editor

fdisk – Partition a disk
mkfs – Create a new filesystem
fsck – Check and repair a filesystem
mount – Mount a filesystem
umount – Unmount a filesystem
parted – Manage disk partitions
blkid – Identify block devices
lsblk – List information about block devices
df -T – Display disk space usage along with filesystem type
lsof – List open files and the processes using them

htop – Interactive process viewer
uptime – Show how long the system has been running
free – Display free and used memory
vmstat – Report virtual memory statistics
iostat – Report CPU and I/O statistics
dmesg – Print kernel message buffer
lshw – List hardware configuration
lsusb – List USB devices
lspci – List PCI devices
uname -a – Print system information

ifconfig – Configure network interfaces
ip a – Display IP address info
netstat – Print network connections
ss – Display socket statistics
nmap – Network exploration tool and security scanner
traceroute – Trace the route packets take to a network host
nslookup – Query internet name servers
dig – Perform DNS lookup
iptables – Configure packet filtering rules
hostname – Show or set the system’s hostname

useradd – Add a new user
usermod – Modify a user account
userdel – Delete a user account
groupadd – Add a new group
passwd – Change user password
su – Switch user accounts
sudo – Execute a command as another user
id – Print user and group IDs
who – Show who is logged on
last – Show the last login of users

apt-get – Package handling utility for Debian-based systems
apt-cache – Search and display package information (Debian-based)
yum – Package manager for RPM-based distributions (e.g., CentOS, RedHat)
dnf – Next-generation version of yum
pacman – Package manager for Arch-based systems
rpm – Install, uninstall, and query RPM packages
dpkg – Debian package manager

rsync -a – Backup files and directories using rsync
tar -czvf – Create a compressed tarball archive
crontab – Schedule tasks to run at specific intervals
at – Schedule a one-time task for later
systemctl – Control the systemd system and service manager
service – Start, stop, or restart a service
journalctl – View system logs (systemd)
history – Show the command history

awk – Pattern scanning and processing language
sed – Stream editor for filtering and transforming text
cron – Task scheduler
tcpdump – Capture network packets
ssh – Secure shell for remote login