150 Essential Linux Commands Every User Should Know

Overview

Linux commands are the core tools for managing a Linux system. The article organizes the commands into logical groups and provides a brief description of each command’s purpose.

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.

mkdir – Create a new directory.

rm – Remove one or more files or directories.

rmdir – Remove empty directories.

touch – Create an empty file or update timestamps.

tree – Display directory contents in a tree structure.

basename – Show the file name or directory name.

dirname – Show the path of a file or directory.

chattr – Change a file’s extended attributes.

lsattr – List a file’s extended attributes.

File and Content Processing (21 commands)

cat – Concatenate files and output to the screen or a file.

tac – Reverse the output of cat.

more – Paginated display of file content.

less – Paginated display (inverse of more).

head – Show the beginning of a file.

tail – Show the end of a file.

cut – Split lines by a delimiter and output selected fields.

split – Split a file into smaller pieces.

paste – Merge lines from multiple files.

sort – Sort text data in a file.

uniq – Remove duplicate lines.

wc – Count lines, words, or bytes.

iconv – Convert file encoding.

dos2unix – Convert DOS line endings to UNIX.

diff – Compare differences between files.

vimdiff – Visual file comparison using Vim.

System Information Commands (11 commands)

uname – Show operating‑system information.

hostname – Display or set the system’s host name.

dmesg – Show kernel boot messages for troubleshooting.

uptime – Display system uptime and load average.

stat – Show file or filesystem status.

df – Report filesystem disk‑space usage.

du – Estimate disk space used by files.

top – Real‑time view of system resource usage.

free – Display memory usage.

date – Show or set the system date and time.

cal – Display a calendar.

Search and Locate Commands (4 commands)

which – Locate a binary in the PATH.

find – Search for files or directories by traversing the filesystem.

whereis – Locate binaries, sources, and manuals.

locate – Search a pre‑built database for file names.

Basic Network Operations (11 commands)

telnet – Remote login using the TELNET protocol.

ssh – Secure remote login using SSH.

scp – Securely copy files between hosts.

wget – Download files from the command line.

ping – Test network connectivity between hosts.

route – View or modify the routing table.

ifconfig – View and configure network interfaces.

ifup – Bring a network interface up.

ifdown – Bring a network interface down.

netstat – Show network status.

ss – Display socket statistics.

Advanced Network Operations (9 commands)

nmap – Network scanning.

lsof – List open files.

nc – Powerful networking utility (netcat).

Disk and Filesystem Commands (16 commands)

mount – Mount a filesystem.

umount – Unmount a filesystem.

fsck – Check and repair filesystems.

dd – Convert and copy files.

dumpe2fs – Dump ext2/3/4 filesystem information.

dump – Backup ext2/3/4 filesystems.

fdisk – Partition disks (up to 2 TB).

parted – Partition disks without size limits.

mkfs – Create a filesystem.

partprobe – Inform the kernel of partition table changes.

e2fsck – Check ext2/3/4 filesystems.

mkswap – Create a swap partition.

swapon – Enable swap.

swapoff – Disable swap.

sync – Flush buffered data to disk.

resize2fs – Resize ext2/3/4 filesystems.

System Permissions and User Management (4 commands)

chmod – Change file or directory permissions.

chown – Change file owner and group.

chgrp – Change group ownership.

umask – Set default permission mask.

User Login Information (7 commands)

whoami – Show the effective username.

who – List currently logged‑in users.

w – Show logged‑in users and their activities.

last – Display recent login sessions.

lastlog – Show the most recent login of all users.

users – List usernames of users currently logged in.

finger – Retrieve detailed user information.

Built‑in and Miscellaneous Commands (19 commands)

echo – Print variables or strings.

printf – Formatted output.

rpm – Manage RPM packages.

yum – Simplified RPM package management.

watch – Periodically execute a command and display output.

alias – Define command aliases.

unalias – Remove command aliases.

date – Show or set system date/time.

clear – Clear the terminal screen.

history – Show command history.

eject – Eject optical media.

time – Measure execution time of a command.

xargs – Build and execute command lines from standard input.

exec – Replace the shell with a specified command.

export – Set or display environment variables.

unset – Remove variables or functions.

type – Determine if a command is built‑in.

bc – Command‑line calculator.

System Management and Performance Monitoring (9 commands)

chkconfig – Manage system startup services.

vmstat – Virtual memory statistics.

mpstat – CPU statistics per processor.

iostat – I/O statistics.

sar – Collect and report system activity.

ipcs – Report inter‑process communication facilities.

ipcrm – Remove IPC objects.

strace – Trace system calls and signals.

ltrace – Trace library calls.

Process Management (15 commands)

bg – Resume a suspended job in the background.

fg – Bring a background job to the foreground.

jobs – List current jobs.

kill – Send a signal to terminate a process.

killall – Kill processes by name.

pkill – Kill processes matching a pattern.

crontab – Schedule recurring tasks.

ps – Snapshot of current processes.

pstree – Tree view of processes.

nice/renice – Adjust process priority.

nohup – Run a command immune to hangup signals.

pgrep – Find processes matching criteria.

runlevel – Show current runlevel.

init – Change the system runlevel.

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

Shutdown and Reboot Commands (6 commands)

shutdown – Shut down the system.

halt – Halt the system.

poweroff – Power off the system.

logout – Log out of the current shell.

exit – Exit the current shell.

Ctrl+d – Shortcut to exit the shell.

By reviewing this list, users can quickly locate the appropriate command for a given task and gain a solid foundation for everyday Linux system administration.