💻 ++101 Linux commands Open-source eBook

This is an open-source eBook with 101 Linux commands that everyone should know. No matter if you are a DevOps/SysOps engineer, developer, or just a Linux enthusiast, you will most likely have to use the terminal at some point in your career.

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Introduction to Linux eBook

If you are looking for a comprehensive guide for beginners, check out this eBook: Introduction to Linux eBook

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Content

• Basics
  • File Hierarchy Standard (FHS)
  • Commands
• Disk and File System Management
  • General Disk Manipulation (non-LVM)
  • Globs (Wildcards)
  • Regex
  • Stream redirection
• Text Readers & Editors
  • Less
  • VI
• User and Group Management
• File System Permissions
• SSH
• Cronjobs
• Package Management
  • RPM
  • YUM
• 📃 List of commands by category:
  • Directory Navigation
  • File Commands
  • File and Directory Manipulation
  • Package archive and compression tools
  • System commands
  • Networking Commands
  • Package Management
  • User Information commands
  • Session commands
  • Getting Help
  • Applications
• 📃 List of commands by chapter:
• 🔗Links
• 📖Other eBooks
• 🤲Contributing

Basics

File Hierarchy Standard (FHS)

Commands

File System Commands

File Manipulation

Archiving

Disk and File System Management

General Disk Manipulation (non-LVM)

Creating physical partitions is not required! You can create PVs directly!

Other

Globs (Wildcards)

The dot . in front of hidden items is ignored by glob patterns!

Regex

Bash itself does not know regex. Use programs like grep, sed, awk.

Control characters

Grep

Stream redirection

• > overwrite
• >> append

Text Readers & Editors

Less

VI

VI/VIM Editing

To leave editing mode press ESC.

Navigation

Navigate as usual with arrow keys, home, end, pg up, pg dn.

Other

User and Group Management

UID

User Database

User info without passwords is stored in /etc/passwd.

Group Database

Group info with secondary group members are stored in /etc/group. Primary group members are identified by GID in user database.

Password Database

Hashed user passwords are stored in /etc/shadow. Password encryption is configured in /etc/login.defs.

PW:

• [hash] Encrypted test password
• ! [hash] Account locked
• !! or * Account locked, no password set

Commands

File System Permissions

Permissions can be set on:

• User (owner)
• Group (owner)
• Others

Only root can change User. User can change Group.

Basic permissions (Add binary flags to combine):

Advanced permissions (place in front of basic permissions: chmod 1777 shared).:

Advanced permissions replace the x when using ls -l. Lower case if x is set, upper case if x is not set.

Read permission on a directory only allows to see the directory itself but not it's contents. Use execute permission to show contents.

Commands

SSH

SSH Configuration is done in /etc/ssh/sshd_config.

Reload SSH service with systemctl reload sshd to apply changes!

DenyUsers, AllowUsers, DenyGroups, AllowGroups override each other and are applied in the order listed above.

Cronjobs

Crontab

Cronjobs are configured in crontab files. Do not edit these files directly. Use crontab -e instead. This runs all required actions to activate a cronjob after saving the edited crontab. The locations are as follows:

• /var/spool/cron/username user specific
• /etc/crontab system wide crontab

The format of the files is (user specific crontabs do not have the column user-name):

Example of job definition:
.---------------- minute (0 - 59 | */5 [every 5 minutes])
|  .------------- hour (0 - 23)
|  |  .---------- day of month (1 - 31)
|  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
|  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
|  |  |  |  |
*  *  *  *  * user-name  command to be executed

Script folders

Scripts in one of the following directories will be executed at the interval specified by the directory's name:

• /etc/cron.hourly
• /etc/cron.daily
• /etc/cron.weekly
• /etc/cron.monthly

Allow / Deny usage

Add user names one per line to the following files:

• /etc/cron.allow Whitelist
• /etc/cron.deny Blacklist

If none of the files exists, all users are allowed.

Logs and Results

Execution of cronjobs is logged in /var/log/cron. Results are sent to the users mail /var/spool/mail/username.

Package Management

RPM

RPM

YUM

YUM is configured in /etc/yum.conf

Repos are configured in /etc/yum.repos.d/

Log is in /var/log/yum.log

📃 List of commands by category:

If you want to contribute, feel free to pick up a topic marked as TODO and submit a pull request 🙌

Feel free to add new topics in case that you don't find one that you like from the current list.

Directory Navigation

• cd - change working directory
• ls - list directory contents
• dir - directory listing, columnar format
• pwd - return working directory name
• tree - list subdirectories in a tree structure

File Commands

• cat/tac - concatenate and print files
• column - format text into columns
• diff/sdiff - compare files line by line
• find - search for files
• grep - file pattern matcher
• head - display the first lines of a file
• locate - find files and directories
• stat - display file status
• tail - display the last lines of a file
• uniq - report or filter out repeated lines in a file

File and Directory Manipulation

• awk - pattern-directed scanning and processing language
• chmod - change permissions
• chown - change file owner and group
• cp - copy files and directories
• cut - remove sections from files
• ln - create links between files
• mkdir - make a new directory
• mv - move files and directories
• nano - text editor
• rm - delete files and directories
• rmdir - remove directory
• paste - merge corresponding or subsequent lines of file
• rsync - remote copy files
• scp - secure copy
• basename - strips directory information and suffixes from file path
• sed - text transformation tool
• sort - arrange or merge lines of files
• split - split a file into pieces
• touch - change file access and modification times
• vim - text editor

Package archive and compression tools

• bzip2 - block-sorting file compressor
• cpio - copy files to/from archives
• gzip - compression tool
• gunzip - decompression tool
• tar - create, extract and manipulate archives
• zip - package and compress files
• unzip - list, test, extract compressed ZIP files

System commands

• badblocks - search for bad blocks on storage devices
• cfdisk - curses-based disk partitioning tool
• crontab - maintain individual tables used to drive the cron daemon
• df - display free disk space
• dmidecode - retrieve hardware information from DMI table
• dmesg - display kernel ring buffer messages
• du - display disk usage statistics
• free - show memory usage information
• fsck - file system check and repair
• hostname - set or print name of current host system
• hostnamectl - change hostname settings
• ionice - get/set I/O process priority
• iostat - I/O statistics
• journalctl - view systemd journal logs
• kill - terminate or signal a process by id
• killall - kill processes by name
• lsb_release - display LSB and distribution information
• lsblk - display block and loop devices
• lsof - list open files
• lspci - list PCI devices
• mkfs - build file systems
• mpstat - CPU statistics
• ncdu - curses-based disk usage
• ps - display process status
• pstree - show processes in tree format
• reboot - restart the system
• service - run an init script
• shutdown - close down the system at a specific time
• systemctl - control systemd services
• top/htop - display process information
• tty - print terminal name
• uname - prints operating system details
• useradd - add/update user accounts
• userdel - delete user account
• usermod - modify user properties
• vmstat - virtual memory statistics
• watch - execute commands repeatedly
• whereis - locate programs

Networking Commands

• dig - DNS lookup utility
• ifconfig - configure network interface parameters
• ip - perform network administration tasks
• iptables - configure netfilter firewall
• lscpu - display CPU architecture information
• netstat - show network status
• nmcli - NetworkManager command line interface
• ping - check network connectivity
• traceroute - trace network path to destination
• ufw - uncomplicated firewall
• whois - information about Internet domain names and network numbers

Package Management

• apt - Debian package management
• rpm - RPM package manager (RedHat)
• yum - package manager for RedHat Linux

User Information commands

For user modification, see useradd, userdel, usermod under System commands

• groups - show group memberships
• finger - shows information about users
• last - displays most recent user logins
• passwd - modify a user's password
• w - display who is logged in and what they are doing
• who - display who is logged in
• whoami - display effective user id

Session commands

• bg - put jobs in background
• clear - clear terminal screen
• env - display environment variables, or set variables for command execution
• exit - close the active session/shell
• export - set environment variables
• fg - bring jobs to foreground
• history - display the command history
• jobs - display active jobs
• login - login and initiate a user session
• nohup - invoke a utility immune to hangups
• printenv - print specified environment variables
• screen - start a screen session
• sleep - suspend execution for a time interval
• ssh - secure shell login
• su - substitute user identity
• sudo - execute a command as another user
• wall - message to all users

Getting Help

• apropos - search manual page names and descriptions
• man - format and display online manual pages
• help - displays help about basic commands not covered by 'man'
• whatis - display one-line command descriptions

Applications

• !! - history expansion (repeat last command)
• bc - basic calculator
• cal - displays a calendar
• cmatrix - enter the Matrix
• curl - transfer data to or from a server
• echo - display interpreted arguments
• factor - prints prime factors of numbers
• printf - format output
• sl - runs a steam locomotive across your terminal
• time - measure command execution time
• wget - non-interactive web file download
• xargs - construct argument lists and execute utility
• yes - print continous output stream
• banner - Writes ASCII character strings in large letters to standard output.
• aplay - aplay is a command-line to play audio files.
• spd-say - plays the given text as the sound from the command line.

📃 List of commands by chapter:

If you want to contribute, feel free to pick up a topic, update it with New Examples | [Options]and submit a pull request 🙌

Feel free to add new topics in case that you don't find one that you like from the current list.

• 001-the-ls-command.md
• 002-the-cd-command.md
• 003-the-cat-tac-command.md
• 004-the-head-command.md
• 005-the-tail-command.md
• 006-the-pwd-command.md
• 007-the-touch-command.md
• 008-the-cal-command.md
• 009-the-bc-command.md
• 010-the-df-command.md
• 011-the-help-command.md
• 012-the-factor-command.md
• 013-the-uname-command.md
• 014-the-mkdir-command.md
• 015-the-gzip-command.md
• 016-the-whatis-command.md
• 017-the-who-command.md
• 018-the-free-command.md
• 019-the-top-htop-command.md
• 020-the-sl-command.md
• 021-the-echo-command.md
• 022-the-finger-command.md
• 023-the-groups-command.md
• 024-the-man-command.md
• 025-the-passwd-command.md
• 026-the-w-command.md
• 027-the-whoami-command.md
• 028-the-history-command.md
• 029-the-login-command.md
• 030-the-lscpu-command.md
• 031-the-cp-command.md
• 032-the-mv-command.md
• 033-the-ps-command.md
• 034-the-kill-command.md
• 035-the-killall-command.md
• 036-the-env-command.md
• 037-the-printenv-command.md
• 038-the-hostname-command.md
• 039-the-nano-command.md
• 040-the-rm-command.md
• 041-the-ifconfig-command.md
• 042-the-ip-command.md
• 043-the-clear-command.md
• 044-the-su-command.md
• 045-the-wget-command.md
• 046-the-curl-command.md
• 047-the-yes-command.md
• 048-the-last-command.md
• 049-the-locate-command.md
• 050-the-iostat-command.md
• 051-the-sudo-command.md
• 052-the-apt-command.md
• 053-the-yum-command.md
• 054-the-zip-command.md
• 055-the-unzip-command.md
• 056-the-shutdown-command.md
• 057-the-dir-command.md
• 058-the-reboot-command.md
• 059-the-sort-command.md
• 060-the-paste-command.md
• 061-the-exit-command.md
• 062-the-diff-sdiff-command.md
• 063-the-tar-command.md
• 064-the-gunzip-command.md
• 065-the-hostnamectl-command.md
• 066-the-iptables-command.md
• 067-the-netstat-command.md
• 068-the-lsof-command.md
• 069-the-bzip2-command.md
• 070-the-service-command.md
• 071-the-vmstat-command.md
• 072-the-mpstat-command.md
• 073-the-ncdu-command.md
• 074-the-uniq-command.md
• 075-the-rpm-command.md
• 076-the-scp-command.md
• 077-the-sleep-command.md
• 078-the-split-command.md
• 079-the-stat-command.md
• 080-the-useradd-command.md
• 081-the-userdel-command.md
• 082-the-usermod-command.md
• 083-the-ionice-command.md
• 084-the-du-command.md
• 085-the-ping-command.md
• 086-the-rsync-command.md
• 087-the-dig-command.md
• 088-the-whois-command.md
• 089-the-ssh-command.md
• 090-the-awk-command.md
• 091-the-crontab-command.md
• 092-the-xargs-command.md
• 093-the-nohup-command.md
• 094-the-pstree-command.md
• 095-the-tree-command.md
• 096-the-whereis-command.md
• 097-the-printf-command.md
• 098-the-cut-command.md
• 099-the-sed-command.md
• 100-the-vim-command.md
• 101-the-chown-command.md
• 102-the-find-command.md
• 103-the-rmdir-command.md
• 104-the-lsblk-command.md
• 105-the-cmatrix-command.md
• 106-the-chmod-command.md
• 107-the-grep-command.md
• 108-the-screen-command.md
• 109-the-nc-command.md
• 110-the-make-command.md
• 111-the-basename-command.md
• 112-the-banner-command.md
• 113-the-alias-command.md
• 114-the-which-command.md
• 115-the-date-command.md
• 116-the-mount-command.md
• 117-the-nice-command.md
• 118-the-wc-command.md
• 119-the-tr-command.md
• 120-the-fdisk-command.md
• 121-the-wait-command.md
• 122-the-zcat-command.md
• 123-the-fold-command.md
• 124-the-quota-command.md
• 125-the-aplay-command.md
• 126-the-spd-say-command.md
• 127-the-xeyes-command.md
• 128-the-parted-command.md
• 129-the-nl-command.md
• 130-the-pidof-command.md
• 131-the-shuf-command.md
• 132-the-less-command.md
• 133-the-nslookup-command.md
• 134-the-cmp-command.md
• 135-the-expr-command.md
• 136-the-wall-command.md
• 137-the-ln-command.md
• 138-the-systemctl-command.md
• 139-the-journalctl-command.md
• 140-the-watch-command.md
• 141-the-jobs-command.md
• 142-the-bg-command.md
• 143-the-fg-command.md
• 144-the-time-command.md
• 145-the-export-command.md
• 146-the-ufw-command.md
• 147-the-traceroute-command.md
• 148-the-nmcli-command.md
• 149-the-badblocks-command.md
• 150-the-fsck-command.md
• 151-the-mkfs-command.md
• 152-the-cpio-command.md
• 153-the-lsb_release-command.md
• 154-the-dmidecode-command.md
• 155-the-apropos-command.md
• 156-the-dmesg-command.md
• 157-the-bangbang-command.md
• 158-the-tty-command.md
• 159-the-lspci-command.md
• 160-the-cfdisk-command.md
• 161-the-column-command.md
• 162-the-nmtui-command.md

🔗Links

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• Ibis Next
• Canva
• Tails

📖Other eBooks

• Introduction to SQL
• Introduction to Git and GitHub
• Introduction to Bash Scripting
• Laravel tips and tricks

📚 eBook Generation

This project uses Ibis Next to generate eBooks in multiple formats:

Quick Start

1. Install dependencies:

composer install

2. Generate eBooks:

# Generate PDF (light theme)
composer run pdf

# Generate PDF (dark theme)
composer run pdf-dark

# Generate EPUB
composer run epub

# Generate HTML
composer run html

Available Formats

• PDF: Available in both light and dark themes, perfect for printing or desktop reading
• EPUB: Compatible with most e-readers, tablets, and mobile devices
• HTML: Single-page HTML version, great for web viewing and sharing

All generated files are saved in the ebook/en/export/ directory.

🤲Contributing

If you are contributing 🍿 please read the contributing file before submitting your pull requests.