Master Essential Linux Commands: A Complete Beginner’s Guide

Linux Basic Commands

Linux platform developers commonly use these commands; mastering them enables proficient use of Linux.

Simple Introduction to Shell

Shell is a command interpreter that translates user commands to the kernel and returns results, protects the operating system, and creates child processes for each command.

The shell program is typically /usr/bin/bash (bash), written in C. When you log into a server, a shell is automatically attached.

Basic Command Format

# command [-options] ...

Built‑in Commands vs External Commands

Linux commands are divided into built‑in commands (integrated in the shell) and external commands (installed as separate binaries, usually located in /bin, /usr/bin, /sbin, etc.). Built‑ins are faster because they do not require a new process.

Check Command Type – type

# type [-afptP] command

Common output types: builtin , file , function , keyword , alias , unfound .

Get Help – help and --help

For built‑in commands use help command. For external commands use command --help (if supported).

Directory Operations

# mkdir directory_name               // create a directory
# mkdir -p d1/d2/d3                 // create nested directories recursively

Print Working Directory – pwd

# pwd                               // display the absolute path of the current directory

Create or Update Files – touch

# touch file_name.ext                // create an empty file
# touch existing_file                // update access and modification timestamps

Output Text – echo

# echo "string" > file              // overwrite file with string
# echo "string" >> file             // append string to file

Understanding Paths

Paths starting with . are hidden. / is the root. . denotes the current directory, .. the parent directory. Windows uses backslashes ( \), Linux uses forward slashes ( /).

List Files – ls

# ls -l                             // long format with permissions
# ls -t                             // sort by modification time
# ls -rt                            // reverse time order
# ls -ul                            // display UID information
# ls -ld /                          // list directory itself, not its contents
# ll -h                             // human‑readable sizes

Change Directory – cd

# cd ~                              // go to home directory
# cd -                              // return to previous directory

Hotkeys / Linux Keyboard Shortcuts

The Tab key provides command auto‑completion. Pressing Tab twice shows all possible matches.

Tree View – tree

# tree [directory]                  // display directory structure as a tree
# yum install -y tree               // install on CentOS/RHEL (use apt‑get on Ubuntu)

Text Editor – nano

# nano file                         // open file with nano editor
# Ctrl+G  // help
# Ctrl+X  // exit
# Ctrl+O  // save
# Ctrl+W  // search
# Ctrl+K  // cut line
# Ctrl+U  // paste

Display File Content – cat

# cat file                         // print file to terminal
# cat -A file                      // show all characters including non‑printing

Compile C – gcc

# gcc source.c                     // compile to a.out
# ./a.out                          // execute the compiled program

File Status – stat

# stat file                        // show file attributes (access, modify, change times)

Remove Files and Directories – rm and rmdir

# rm file                          // delete file
# rm -f file                       // force delete without prompt
# rm -r dir                        // recursively delete directory
# rm -rf dir                       // force recursive delete
# rmdir dir                        // delete empty directory only

Directory Permissions

Regular users can create files only under /home/username/…; root can create files anywhere.

Number of Linux Commands

On a typical Alibaba Cloud lightweight instance there are about 1,265 commands.

Manual Pages – man

# yum install -y man-pages        // install manual pages
# man command                      // view manual for a command
# man 2 printf                     // section 2 (system calls)
# man 3 printf                     // section 3 (C library)

Privilege Escalation – sudo

# sudo command                     // run command as superuser

Copy Files – cp

# cp file dir                       // copy file into directory
# cp -r dir1 dir2                  // recursively copy directory

Command Alias – alias

# alias ll='ls -l --color=auto'    // example alias for colored long listing

Search – find , which , whereis

# find /path -name filename        // locate file by name
# which command                    // show full path of executable
# whereis command                  // show binary, source, and man page locations

Command Alias – alias

# alias name='command options'      // define shortcut for a command with options

Pattern Search – grep

# grep 'keyword' file              // print lines containing keyword
# grep -v 'keyword' file           // print lines NOT containing keyword
# grep -i 'keyword' file            // case‑insensitive search
# grep -E 'pattern1|pattern2' file // extended regex OR search

System Monitor – top

# top                              // interactive process viewer

Common options: -a (sort by memory), -b (batch mode), -n (number of iterations), -p PID (show specific PID), -u USER (show processes of a user), etc.

Compression – zip and unzip

# zip archive.zip file1 file2       // create zip archive
# zip -r archive.zip directory      // recursively zip a directory
# unzip archive.zip                 // extract to current directory
# unzip archive.zip -d /path        // extract to specified directory

Archive – tar

# tar -czf archive.tgz files        // create gzipped tarball
# tar -xzf archive.tgz              // extract gzipped tarball
# tar -ztvf archive.tgz             // list contents without extracting

Calculator – bc

# bc                               // start interactive calculator
# echo "1+2*3/2" | bc              // evaluate expression (outputs 4)

System Information – uname

# uname -a                         // all system information
# uname -r                         // kernel release
# uname -m                         // machine hardware name

Exit Terminal – exit

# exit                             // close the shell (Ctrl+D works as well)

Command History – history

# history                         // show recent commands
# history > file.txt               // save history to a file
# !123                             // execute command number 123
# !!                               // repeat last command

Reboot – reboot

# reboot                           // restart the system

Shutdown – shutdown

# shutdown -h now                 // halt immediately
# shutdown -r now                 // reboot immediately
# shutdown -c                     // cancel a pending shutdown

Poweroff – poweroff

# poweroff                         // turn off the machine (equivalent to halt)

Useful Keyboard Shortcuts

Ctrl+S – pause terminal output; Ctrl+Q – resume.

Ctrl+C – terminate the current foreground process.

Ctrl+R – reverse search through command history.

Arrow keys – navigate command line.

In Linux, everything is a file – keyboards, displays, and even processes can be read from or written to.