Some linux commands

100+ Linux commands that Linux Sysadmins regularly use, with explanation.

Thank you @linuxopsys.

100+ Linux commands that Linux Sysadmins regularly use, with explanation

• cut : allows you to cut out sections of a specified file or piped data and print the result to standard output.
• sort : used to sort files
• uniq : used to extract uniq occurences
• tr : utility for translating or deleting characters.
• grep : searches a file for a pattern of characters and displays all lines that match.
• awk : a scripting language used for text processing.
• sed : stream editor used to perform lots of functions on files, like searching, find and replace, insertion, or deletion.
• pstree : used to show running processes in a tree (data structure).
• latest : displays a list of the most recently logged-in people.
• w : display a list of the currently logged-in user sessions.
• free : use to get a detailed report on the system’s memory usage.
• scp : securely copy files or directories over ssh.
• find : locates files using user-defined criteria.
• ncdu : provides a useful and convenient way to view disk usage.
• ip : used to show or manipulate routing, devices, and tunnels.
• ls : list the contents of a directory.
• df : Displays the amount of disk space used.
• du : display a list of all the files along with their respective sizes.
• diff : used to display differences in files by comparing line by line.
• uptime : displays the system uptime as well as the load average.
• top : shows a real-time view of running processes in Linux.
• dstat : allows you to view all of your system resources instantly. All-in-one vmstat, iostat, netstat, and ifstat utility.
• Iftop is a network traffic viewer.
• nethogs : is a network traffic analyzer.
• vmstat : used to obtain information about memory, system processes, paging, interrupts, block I/O, disk, and CPU scheduling.
• htop : a process viewer and manager that is interactive.
• iotop : is an interactive I/O viewer. Get a snapshot of storage r/w activity.
• iostat : provides statistics on storage I/O.
• netstat : used to show network statistics.
• ss : ss command is a simpler and faster version of the now obsolete netstat command.
• atop : a tool for monitoring system resources in Linux.
• ssh : secure protocol used as the primary means of connecting to Linux servers remotely.
• sudo : run commands with administrative privileges.
• cd : navigate between directories.
• touch : used to create, update a computer file or directory’s access and modification dates.
• man : used to read system reference manuals.
• apropos : searches manual page names and descriptions for a user-supplied keyword.
• pwd : displays the current directory path.
• cp : copy files and directories.
• mv : move file or directories.
• rm : deletes files and directories.
• mkdir : create new directories.
• rsync : remote file transfer and synchronization.
• tar : is an archive utility.
• gzip : use for compression and decompression of files.
• b2zip : a compression utility comparable to gzip. It employs a distinct compression algorithm.
• zip : used for file packaging and compression (archiving).
• locate : in Linux, search for files.
• ps : allows you to list the status of processes running on your system easily.
• cron : execute scheduled tasks.
• mtr : is a network diagnostic tool, a combination of ping and traceroute commands.
• nslookup : interactively query Internet name servers (NS).
• host : used for DNS (Domain Name System) lookup operations.
• dig : DNS lookup tool.
• nmcli : sused to display network device status, create, edit, activate/deactivate, and delete network connections.
• ping : sends an ICMP ECHO REQUEST to network hosts.
• traceroute : examine the path packets follow to reach a specific host.
• wget : download files through HTTP, HTTPS, FTP, and FTPS.
• curl : data transport via several network protocols. (Can handle more protocols than wget)
• dd : used to convert and copy files.
• fdisk : Modify the disk partition table.
• parted : used to create and manipulate partition tables.
• blkid : a command-line utility for finding and printing block device attributes.
• mkfs : create a Linux file system.
• fsck : an utility for determining the consistency of a file system.
• nc : used for just about anything under the sun involving TCP or UDP.
• umask : returns, or sets, the value of the system’s file mode creation mask.
• chmod : alters the access rights of file system objects.
• chown : alter the owner and group of a file.
• chroot : used to change the root directory.
• useradd : create a new user or alter the default information for a new user.
• userdel : used to delete a user account and all associated files.
• usermod : used to edit or change any existing user account’s properties.
• vi is a text editor.
• cat : displays the contents of a file.
• tac : reverse output file contents.
• more : show file contents one screen/page at a time.
• less : identical to more, but with more features
• tail : used to show the last few lines of a text file or piped data.
• head : used to show the first few lines of a text file or piped data.
• dmesg : displays the kernel ring’s message buffer.
• journalctl : Tused to view systemd, kernel and journal logs.
• kill : terminates a process.
• killall : sends a kill signal to all instances of a specific process.
• sleep : pauses program execution for a given amount of time.
• wait : suspend script execution until all background jobs have been completed.
• nohup : short for no hang up is a command in Linux systems that keep processes running even after exiting the shell or terminal.
• screen : keep a remote server session open. (It also functions as a full-screen window manager.)
• tmux is a terminal multiplexer.
• passwd — Change the password of a user.
• clear : clears the terminal’s screen.
• env : run a command in an altered environment
• mount : used to mount the filesystem found on a device to big tree structure(Linux filesystem) rooted at ‘/’.
  92 : umount : unmounts a previously mounted device, directory, file, or file system.
• systemctl : used to control and manage systemd and services.
• alias : defines an alias for the specified command.
• at : runs a specified script or command at a set later time.
• atq : shows jobs in the at utility queue.
• atrm : deletes the specified job from the at utility queue.
• bash : uses the Bourne Again Shell command language to interpret commands from standard input or a file, or to launch a subshell.
• bc : Performs calculations via its programming language.
• bash : uses the Bourne Again Shell command language to interpret commands from standard input or a file, or to launch a subshell.
• bc : Performs calculations via its programming language.
• chfn : changes the specified user account’s current information.
• chgrp : changes the default group of the specified file or directory.
• chmod : changes system security permissions for the specified file or directory
• chown : changes the default owner of the specified file or directory.
• chpasswd : reads a file of login name and password pairs and updates the passwords.
• chsh : changes the specified user account’s default shell.
• continue : resumes the next iteration of a for , while , select , or until loop.
• coproc : spawns a subshell in background mode and executes the designated command or executes a coprocess.
• env : executes the designated program in a modified environment or displays the value of all the environment variables.
  → arp – see your arp table.
  → aria2 – downloading just about everything. Torrents included.
  → arpwatch – Ethernet Activity Monitor.
  → bmon – bandwidth monitor and rate estimator.
  → bwm-ng – live network bandwidth monitor.
  → curl – transferring data with URLs.(or try httpie)
  → darkstat – captures network traffic, usage statistics.
  → dhclient – Dynamic Host Configuration Protocol Client
  → dig – query DNS servers for information.
  → dstat – replacement for vmstat, iostat, mpstat, netstat and ifstat.
  → ethtool – utility for controlling network drivers and hardware.
  → gated – gateway routing daemon.
  → host – DNS lookup utility.
  → hping – TCP/IP packet assembler/analyzer.
  → ibmonitor – shows bandwidth and total data transferred.
  → ifstat – report network interfaces bandwidth.
  → iftop – display bandwidth usage.
  → ip – a command with more features than ifconfig.
  → iperf3 – network bandwidth measurement tool.
  → iproute2 – collection of utilities for controlling TCP/IP.
  → iptables – take control of network traffic.
  → IPTraf – An IP Network Monitor.
  → iputils – set of small useful utilities for Linux networking.
  → iw – a new nl80211 based CLI configuration utility → for wireless devices.
  → jwhois (whois) – client for the whois service.
  → lsof -i – reveal information about your network sockets.
  → mtr – network diagnostic tool.
  → net-tools – utilities include: arp, hostname, ifconfig, netstat, rarp, route, plipconfig, slattach, mii-tool, iptunnel and ipmaddr.
  → ncat – improved re-implementation of the venerable netcat.
  → netcat – networking utility for reading/writing network connections.
  → nethogs – a small ‘net top’ tool.
  → Netperf – Network bandwidth Testing.
  → netplan – Netplan is a utility for easily configuring
  → networking on a linux system.
  → netsniff-ng – Swiss army knife for daily Linux network plumbing.
  → netwatch – monitoring Network Connections.
  → ngrep – grep applied to the network layer.
  → nload – display network usage.
  → nmap – network discovery and security auditing.
  → nmcli – a command-line tool for controlling NetworkManager and reporting network status.
  → nmtui – provides a text interface to configure networking by controlling NetworkManager.
  → nslookup – query Internet name servers interactively.
  → ping – send icmp echo_request to network hosts to test connectivity.
  → route – show / manipulate the IP routing table.
  → slurm – network load monitor.
  → snort – Network Intrusion Detection and Prevention System.
  → smokeping – keeps track of your network latency.
  → socat – establishes two bidirectional byte streams and transfers data between them.
  → speedometer – Measure and display the rate of data across a network.
  → speedtest-cli – test internet bandwidth using http://speedtest.net
  → ss – utility to investigate sockets.
  → ssh – secure system administration and file transfers over insecure networks.
  → tcpdump – command-line packet analyzer.
  → tcptrack – Displays information about tcp connections on a network interface.
  → telnet – user interface to the TELNET protocol.
  → tracepath – very similar function to traceroute.
  → traceroute – print the route packets trace to network host.
  → vnStat – network traffic monitor.
  → websocat – Connection forwarder from/to web sockets to/from usual sockets, in style of socat.
  → wget – retrieving files using HTTP, HTTPS, FTP and FTPS.
  → Wireless Tools for Linux – includes iwconfig, iwlist, iwspy, iwpriv and ifrename.
  → Wireshark – network protocol analyzer.