Ultimate Linux Command Cheat Sheet: Master File, Network, and System Operations

Linux Command Overview

Linux commands are the core tools for managing a Linux system, where devices, files, and processes are treated as files.

Help and Query Commands

man : View command help and manual pages.

help : Show help for built‑in shell commands.

File and Directory Operations (18 commands)

ls : List directory contents and attributes.

cd : Change the current working directory.

cp : Copy files or directories.

mv : Move or rename files.

find : Search for files and directories.

mkdir : Create new directories.

rmdir : Remove empty directories.

rm : Delete files or directories.

rename : Rename files.

touch : Create an empty file or update timestamps.

tree : Display directory structure as a tree.

basename : Show the base name of a file path.

dirname : Show the directory part of a file path.

chattr : Change a file's extended attributes.

lsattr : List a file's extended attributes.

File Content Commands (21 commands)

cat : Concatenate and display file contents.

tac : Display file contents in reverse order.

more : Paginate output.

less : Paginate output with backward navigation.

head : Show the beginning of a file.

tail : Show the end of a file.

cut : Extract sections from each line of a file.

split : Split a file into smaller pieces.

paste : Merge lines of files.

sort : Sort lines of text.

uniq : Remove duplicate lines.

wc : Count lines, words, or bytes.

iconv : Convert file encoding.

dos2unix : Convert DOS line endings to UNIX.

File Compression and Archiving (4 commands)

tar : Archive files.

unzip : Extract ZIP archives.

gzip : Compress files using gzip.

zip : Create ZIP archives.

System Information Commands (11 commands)

uname : Show kernel and OS information.

hostname : Display or set the system hostname.

dmesg : Print kernel ring buffer messages.

uptime : Show system uptime and load.

stat : Display file or filesystem status.

du : Estimate file space usage.

df : Report filesystem disk space usage.

top : Real‑time view of system processes.

free : Show memory usage.

date : Display or set the system date and time.

cal : Display a calendar.

Basic Network Operations (11 commands)

telnet : Remote login using the TELNET protocol.

ssh : Secure remote login via SSH.

scp : Securely copy files between hosts.

wget : Download files from the web.

ping : Test network connectivity.

route : Show or modify the routing table.

ifconfig : Configure network interfaces.

ifup : Bring a network interface up.

ifdown : Bring a network interface down.

netstat : Display network connections and routing tables.

ss : Show socket statistics.

Advanced Network Tools (9 commands)

nmap : Network scanner.

lsof : List open files.

mail : Send and receive email.

mutt : Text‑based email client.

nslookup : Query DNS.

dig : Perform DNS lookups.

host : DNS lookup utility.

traceroute : Trace the route packets take.

tcpdump : Capture network packets.

Disk and Filesystem Commands (16 commands)

mount : Mount a filesystem.

umount : Unmount a filesystem.

fsck : Check and repair a filesystem.

dd : Convert and copy files.

dumpe2fs : Dump ext2/3/4 filesystem information.

dump : Backup ext2/3/4 filesystems.

fdisk : Partition a disk (up to 2 TB).

parted : Partition disks of any size.

mkfs : Create a filesystem.

partprobe : Inform the kernel of partition table changes.

e2fsck : Check ext2/3/4 filesystems.

mkswap : Set up a swap area.

swapon : Enable swap.

swapoff : Disable swap.

sync : Flush filesystem buffers.

resize2fs : Resize ext2/3/4 filesystems.

System Permissions and Ownership (4 commands)

chmod : Change file permissions.

chown : Change file owner and group.

chgrp : Change group ownership.

umask : Set default permission mask.

User Management (10 commands)

useradd : Add a new user.

usermod : Modify an existing user.

userdel : Delete a user.

groupadd : Add a new group.

passwd : Change a user's password.

chage : Change password expiry information.

id : Show user and group IDs.

su : Switch user identity.

visudo : Safely edit the sudoers file.

sudo : Execute a command as another user (default root).

System Login Information (7 commands)

whoami : Print the effective username.

who : Show who is logged on.

w : Display logged‑in users and their activities.

last : Show a list of last logged‑in users.

lastlog : Show the most recent login of all users.

users : List logged‑in usernames.

finger : Display user information.

Built‑in and Miscellaneous Commands (19 commands)

echo : Print arguments to standard output.

printf : Format and print data.

rpm : Manage RPM packages.

yum : High‑level package manager for RPM.

watch : Execute a program periodically, showing output fullscreen.

alias : Define or display command aliases.

unalias : Remove command aliases.

clear : Clear the terminal screen.

history : Show command history.

eject : Eject removable media.

time : Measure program execution time.

nc : Netcat – versatile networking utility.

xargs : Build and execute command lines from standard input.

exec : Replace the shell with a specified command.

export : Set environment variables.

unset : Unset shell variables or functions.

type : Indicate how a name would be interpreted if used as a command.

bc : Arbitrary‑precision calculator language.

System Management and Monitoring (9 commands)

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chkconfig : Manage system services at boot time.

vmstat : Report virtual memory statistics.

mpstat : Show per‑CPU statistics.

iostat : Report CPU and I/O statistics.

sar : Collect, report, or save system activity information.

ipcs : Report inter‑process communication facilities.

ipcrm : Remove IPC objects.

strace : Trace system calls and signals.

ltrace : Trace library calls.

Shutdown, Reboot, and Logout (6 commands)

shutdown : Shut down the system.

halt : Halt the system.

poweroff : Power off the machine.

logout : Exit a login shell.

exit : Exit the current shell.

Ctrl+d : Shortcut to exit the shell.

Process Management (15 commands)

bg : Resume a stopped job in the background.

fg : Bring a background job to the foreground.

jobs : List active jobs.

kill : Send a signal to a process.

killall : Kill processes by name.

pkill : Kill processes matching criteria.

crontab : Schedule recurring tasks.

ps : Report a snapshot of current processes.

pstree : Display processes as a tree.

nice/renice : Adjust process priority.

nohup : Run a command immune to hangups.

pgrep : Search for processes by name.

runlevel : Show the current system runlevel.

init : Change the system runlevel.

service : Start, stop, restart, or query system services.