A (Basic) Linux Knowledge Bank
Welcome to The Linux Wiki, a generalist System Administrator resource focused on Red Hat Enterprise Linux™ release 8, including derivatives of RHEL such as
CentOS,
Rocky and
Alma Linux. It also provides some knowledge on
HPC, and keeps learning notes on
AWS and
Raspberry Pi. Existing material on
CentOS or RHEL EOL versions will not be maintained any more. This is always a "work in progress"!
| Filesystem operations
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| cd → Change directory
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| chattr → Change file attributes on a Linux file system
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| chgrp → Change group ownership.
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| chmod → Change file mode bits
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| chown → Change file owner and group
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| cp → Copy files and directories
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| df → Report file system disk space usage
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| du → Estimate file space usage
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| find → Search for files in a directory hierarchy
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| ls → List directory contents
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| mkdir → Make directories
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| mv → Move (rename) files
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| pwd → Print name of current/working directory
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| rm → Remove files or directories
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| Operations on files
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| bzip2 → A block-sorting file compressor
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| cat → Concatenate files and print on the standard output
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| cmp → Compare two files byte by byte
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| comm → Compare two sorted files line by line
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| cut → Remove sections from each line of files
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| diff → Compare files line by line
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| fdupes → finds duplicate files in a given set of directories
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| file → Determine file type
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| grep → Print lines matching a pattern
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| gzip → The GNU data compression program
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| head → Output the first part of files
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| hexdump → Display file contents in ascii, decimal, hexadecimal, or octal
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| join → Join lines of two files on a common field
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| last → Output the last part of files
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| less → File perusal filter
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| more → File perusal filter
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| paste → Merge lines of files.
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| sed → Stream editor for filtering and transforming text
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| sort → Sort lines of text files
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| stat → Display file or file system status
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| strings → Print the strings of printable characters in files
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| tail → Output the last part of files
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| tar → Tape archiver
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| tee → read from standard input and write to standard output and files
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| tr → Translate or delete characters
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| wc → Print newline, word, and byte counts
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| xz → File compressor
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| Networking Tools
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| ethtool → Display or change ethernet card settings
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| hostname → Show or set the system's host name.
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| ifconfig → Configure a network interface
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| iftop → Display bandwidth usage on an interface by host
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| ip → Show / manipulate routing, devices, policy routing and tunnels
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| ncat → Concatenate and redirect sockets
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netstat → Print network connections, routing tables, interface statistics,
masquerade connections, and multicast memberships
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| nmap → Network exploration tool and security / port scanner
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| ping → Send ICMP ECHO_REQUEST to network hosts
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| ss → Another utility to investigate sockets
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| tcpdump → dump traffic on a network
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| traceroute → Print the route packets trace to network host
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| Processes toolset
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| atop → Advanced System & Process Monitor
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| htop → Interactive process viewer
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| kill → Signal / terminate a process
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| lsof → Lists open files
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| nice → Run a program with modified scheduling priority
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| ps → Report a snapshot of the current processes
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| pgrep / pkill → Look up or signal processes based on name and other attributes
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| pidof → Find the process ID of a running program
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| pstree → Display a tree of processes
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| renice → Alter priority of running processes
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| top → Display Linux processes
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| User Management
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| chage → Change user password expiry information
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| finger → User information lookup program
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| getent → Get entries from Name Service Switch libraries
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| groupadd → Add group
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| id → Print real and effective user and group IDs
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| passwd → Set password
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| su → Run a command with substitute user and group ID
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| sudo → Allows restricted root access for specified users
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| useradd → Add user
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| userdel → Delete user
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| usermod → Modify a user account
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| w → Show who is logged in and what are they doing
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| who → Show who is logged in
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| LAMP
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| HAProxy → TCP/HTTP proxy and load balancer
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| httpd → The Apache web server
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| PHP → PHP scripting language
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| MySQL → MySQL/MariaDB Database
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| nginx → HTTP and reverse proxy server
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| PostgreSQL → Postgres Database
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| HTML → Hypertext Markup Language
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| SSL → Secure Sockets Layer
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| Internet tools
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| curl → Transfer a URL
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| dig → DNS lookup utility
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| host → DNS lookup utility
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| links → Character mode WWW browser
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| nslookup → Query Internet name servers interactively
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| wget → The non-interactive network downloader
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| whois → Client for the whois directory service
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| Scripting and Programming
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| awk → A pattern scanning and processing language
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| perl → Practical Extraction and Report Language
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| bash PL → Bash (scripting)
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Python → An interpreted, interactive, object-oriented
programming language
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| Shells
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| bash → GNU Bourne-Again SHell
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| zsh → Z shell
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| Version control
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| RCS → Revision Control System
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| git → Fast Version Control System
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| subversion → The subversion Version Control System
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| Hardware queries
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| inxi → Command line system information script for console and IRC
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| lscpu → Display information about the CPU architecture
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| lshw → List hardware
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| lspci → List all PCI devices
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| lsusb → List USB devices
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| lstopo → Show the topology of the system
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| Services management
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| chkconfig → Updates and queries runlevel information for system services (legacy)
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| service → Run a System V init script (legacy)
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| systemctl → Control the systemd system and service manager
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| Disk & filesystem stuff
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| LVM → LVM2 tools
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| NFS → Network File System
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| automount → Manage autofs mount points
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| exportfs → Maintain table of exported NFS file systems
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| fdisk → Manipulate disk partition table
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| gdisk → Manipulate disk partition table
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| mount → Mount a filesystem
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| parted → Partition Editor
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| Frequently used network clients
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| ftp → File Transfer Protocol
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| rsync → Remote (and local) file-copying tool
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| scp → Secure Copy
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| sftp → Secure file transfer program
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| ssh → Secure shell
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| telnet → User interface to the TELNET protocol
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| Frequently used utilities
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| expect → A program-script interaction and testing utility
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| man → An interface to the on-line reference manuals
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| multitail → Browse through several files at once
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| screen → Screen manager with VT100/ANSI terminal emulation
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| script → Make typescript of terminal session
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| Package Management
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| dnf → Package Manager
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| rpm → RPM Package Manager
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| yum → Yellowdog Updater Modified
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Knowledge Bank
Disclaimer
- All the information here is presented without any warranty or guarantee of accuracy. Use it at your own risk. When in doubt, please consult the man pages or the GNU info pages as the authoritative references.
- Some contents created starting 2024 are produced or enhanced by AI tools such as Chat GPT, Microsoft Copilot, or you.com.
Iterate toward perfection. Treat perfection like a process, not an achievable state.