Linux Commands

Inhalt

Command Overview
Commands by Category

Depending on the distribution, some commands may need to be installed first, e.g. whois or dig.

Commands can accept many more parameters than listed here. All available parameters can be taken from the help with man [COMMAND]. The parameters can also be displayed with [COMMAND] --help or [COMMAND] -h.

Some commands or arguments require execution with the command sudo.

Command Overview

Command	Description
!!	Execute the last command ^!!!
> [FILE]	Create empty file ^!!!
badblocks -s /dev/[DEVICE]	Drive check ^sudo
cal	Shows current month calendar
cat /etc/group	Shows all groups
cat /etc/passwd	Shows all users
cat /proc/cpuinfo	CPU information
cat [FILE]	Output file content
cat [SOURCE] >> [TARGET]	Append file content to another file
cd ..	Go to parent directory
cd [DIRECTORY]	Go to a directory
cd ~	Go to home directory
chmod [RIGHTS] [FILE]	Change file permissions ^{sudo !!!}
chown [USER] [FILE]	Change file owner ^{sudo !!!}
chown [USER]:[GROUP] [FILE]	Change file owner and group ^{sudo !!!}
cp -r [SOURCE] [DESTINATION]	Copy a directory
cp [SOURCE] [DESTINATION]	Copy a file
date	Shows current date and time
date -R	Shows current date and time (RFC-5322)
date -u	Shows current date and time (UTC)
df -h	Shows free and used disk space
dig [HOST] ANY	Show DNS information
dmesg	Bootup messages ^sudo
dmidecode	System information ^sudo
dmidecode --dump-bin [FILE]	System information (dump to file) ^sudo
dmidecode --from-dump [FILE]	System information (read from file)
du -ah [PATH]	Shows disk usage
exit	Exit the current shell
fdisk -l	Shows partitions ^{sudo !!!}
find [PATH] -name [EXPRESSION]	Search for files in a directory
findmnt	List all file systems
free -h	Memory usage
gpg -c [FILE]	Encrypt a file
gpg -d [FILE]	Decrypt a file
grep -Hnir [TERM] [DIRECTORY]	Recursive search in a directory
grep -i [TERM] [FILE]	Search in a file
groupadd [GROUP]	Create new group ^sudo
groupdel [GROUP]	Remove a group ^{sudo !!!}
groups	Shows current groups
gzip -d [FILE]	Decompress file with GNU ZIP
gzip -k [FILE]	Compress file with GNU ZIP
hdparm -g /dev/[DEVICE]	Drive geometry ^{sudo !!!}
hdparm -i /dev/[DEVICE]	Drive information ^{sudo !!!}
hdparm -tT /dev/[DEVICE]	Drive read-speed test ^{sudo !!!}
head [FILE]	Shows the first 10 lines of a file
hostname	Shows the system hostname
hostname -i	Shows the system IP address
id	Shows current user information
id -un	Shows the own user name
id [USER]	Shows user information
ip addr	List IP addresses and network interfaces
ip route	Shows routing table
kill [PID]	Kill a process by its PID ^!!!
killall [NAME]	Kill all processes with a given name
last	Shows last logged in users
last reboot	Shows system reboot history
less [FILE]	Shows file content
ln -s [TARGET] [NAME]	Create a symbolic link
locate [TERM]	Search for files
ls	List files in directory
ls -la	List all files in directory
lsblk	Block devices
lsof	List all open files
lspci	PCI devices
lspci -tv	PCI devices (tree)
lspci -v	PCI devices (verbose)
lsusb	USB devices
lsusb -tv	USB devices (tree)
lsusb -v	USB devices (verbose)
mkdir [DIRECTORY]	Create new directory
more [FILE]	Shows file content
mv [SOURCE] [DESTINATION]	Rename or move a file or directory ^!!!
ping [HOST]	Ping a host
pkill [NAME]	Kill a process by its name ^!!!
pmap [PID]	Shows memory map o a process
ps -aux	Shows all processes
pstree	Shows processes (tree)
pwd	Shows current directory path
rm -r [DIRECTORY]	Remove directory ^!!!
rm [FILE]	Remove file ^!!!
ss -ap	Shows open ports
tail [FILE]	Shows the last 10 lines of a file
tar cf [TARGET] [FILES]	Compress files with TAR
tar czf [TARGET] [FILES]	Compress files with TAR and GNU ZIP
tar xf [FILE]	Extract files with TAR
top	Shows processes (in real-time)
touch [FILE]	Change file time ^!!!
traceroute -I [HOST]	Trace route to a host
uname -a	Shows system and kernel information
uptime -p	Shows system running time
uptime -s	Shows system start time
useradd [USER]	Create new user ^sudo
userdel [USER]	Remove user ^{sudo !!!}
usermod -aG [GROUP] [USER]	Add a user to groups ^{sudo !!!}
users	Shows logged in users
w	Shows logged in users and their activity
wc [FILE]	Count lines, words and bytes of a file
who	Shows logged in users
who -b	Shows system boot time
whoami	Shows the own user name
whois [HOST]	Get whois information

Commands by Category

Disks and Partitions

df -h: Shows the free and used space on all file systems.
du -ah [PATH]: Shows the disk usage for the specified [PATH]. Without a path, the current path is used.
fdisk -l: Lists all partitions, sizes and types.
Execute with sudo / Caution when using
findmnt: Lists all file systems.

File Compression

gzip -d [FILE]: Decompresses a [FILE] with GNU ZIP.
gzip -k [FILE]: Compresses a [FILE] with GNU ZIP and store the compressed file as "[FILE].gz". Without the option "-k", the original file will be removed.
tar cf [TARGET] [FILES]: Compresses one or more [FILES] with TAR and store it as [TARGET] file (e.g. "archive.tar").
tar czf [TARGET] [FILES]: Compresses one or more [FILES] with TAR and GNU ZIP and store it as [TARGET] file (e.g. "archive.tar.gz").
tar xf [FILE]: Extracts files from a TAR [FILE].

File Permissions

chmod [RIGHTS] [FILE]: Changes the file permissions for a [FILE]. The [RIGHTS] can be entered as octal code (digits 0-7) in the order owner-group-others. Rights: 4=read, 2=write, 1=execute, 0=none. Examples: 777=all rights for all users, 644=read and write for owner, read only for all other.
Execute with sudo / Caution when using
chown [USER] [FILE]: Changes the owner of the [FILE] to the specified [USER].
Execute with sudo / Caution when using
chown [USER]:[GROUP] [FILE]: Changes the owner and the [GROUP] of the [FILE] to the specified [USER].
Execute with sudo / Caution when using

Files and Directories

> [FILE]: Creates a new empty [FILE]. If the [FILE] exists, it's size will be set to 0.
Caution when using
cat [FILE]: Outputs the content of a [FILE].
cat [SOURCE] >> [TARGET]: Appends the content of one or more [SOURCE] files to a [TARGET] file.
cp -r [SOURCE] [DESTINATION]: Copies a [SOURCE] directory to a [DESTINATION] directory with its entire content.
cp [SOURCE] [DESTINATION]: Copies a [SOURCE] file to a [DESTINATION] file or directory.
gpg -c [FILE]: Encrypts a [FILE]. Password will be prompted.
gpg -d [FILE]: Decrypts a [FILE].
head [FILE]: Shows the first 10 lines of a [FILE].
less [FILE]: Shows the content of a [FILE]. Lines and/or pages are scrollable.
ln -s [TARGET] [NAME]: Creates a symbolic link with the given [NAME] to a [TARGET] file or directory.
mkdir [DIRECTORY]: Creates a new [DIRECTORY].
more [FILE]: Shows the content of a [FILE]. Lines and/or pages are scrollable.
mv [SOURCE] [DESTINATION]: Moves a [SOURCE] file or directory to a new [DESTINATION] or rename it.
Caution when using
pwd: Prints full path of the current working directory.
rm -r [DIRECTORY]: Removes a [DIRECTORY] with its entire content.
Caution when using
rm [FILE]: Removes the specified [FILE].
Caution when using
tail [FILE]: Shows the last 10 lines of a [FILE].
touch [FILE]: Changes the access and modification time of a [FILE] to the current time. touch creates the [FILE], if it does not exist.
Caution when using
wc [FILE]: Counts lines, words and bytes in the content of a [FILE].

Hardware

badblocks -s /dev/[DEVICE]: Checks a [DEVICE] for unreadable blocks.
Execute with sudo
cat /proc/cpuinfo: Shows CPU information.
dmesg: Shows messages from system bootup.
Execute with sudo
dmidecode: Shows information about BIOS, system, mainboard and chassis.
Execute with sudo
dmidecode --dump-bin [FILE]: Dumps information about BIOS, system, mainboard and chassis in a binary file.
Execute with sudo
dmidecode --from-dump [FILE]: Shows information about BIOS, system, mainboard and chassis from a binary dump file.
free -h: Shows free and used memory.
hdparm -g /dev/[DEVICE]: Shows drive geometry of the specified [DEVICE].
Execute with sudo / Caution when using
hdparm -i /dev/[DEVICE]: Shows drive information about the specified [DEVICE].
Execute with sudo / Caution when using
hdparm -tT /dev/[DEVICE]: Performs a read-speed test for the specified [DEVICE].
Execute with sudo / Caution when using
lsblk: Shows information about block devices.
lspci: Shows information about PCI devices.
lspci -tv: Shows information about PCI devices as tree.
lspci -v: Shows verbose information about PCI devices.
lsusb: Shows information about USB devices.
lsusb -tv: Shows information about USB devices as tree.
lsusb -v: Shows verbose information about USB devices.

Navigation

cd ..: Goes to the parent directory.
cd [DIRECTORY]: Goes to the specified [DIRECTORY].
cd ~: Goes to the users hone directory.

Network

dig [HOST] ANY: Shows DNS information for a [HOST].
ip addr: Shows addresses assigned to all network interfaces.
ip route: Shows the routing table.
ping [HOST]: Performs a ping to a given [HOST].
ss -ap: Shows a list with all open sockets, including the ports and the processes using these sockets.
traceroute -I [HOST]: Traces the route to a [HOST] per ICMP ECHO.
whois [HOST]: Shows whois information for a [HOST].

Processes

kill [PID]: Kills a process with the specified [PID].
Caution when using
killall [NAME]: Kills all processes with the specified [NAME].
lsof: Lists all files opened by running processes.
pkill [NAME]: Kills a process with the specified [NAME].
Caution when using
pmap [PID]: Shows the memory map of the process specified by its [PID].
ps -aux: Shows all processes running on the system.
pstree: Shows running processes as tree.
top: Shows running processes in real-time.

Search

find [PATH] -name [EXPRESSION]: Searches in a given [PATH] for file names with the specified [TERM] (incl. placeholders like "*" and "?").
grep -Hnir [TERM] [DIRECTORY]: Searches recursive for a case-invariant [TERM] in all files of a [DIRECTORY] and display the filename and line number.
grep -i [TERM] [FILE]: Searches for a [TERM] in a [FILE].
locate [TERM]: Search for file names with a given [TERM].
ls: Lists files in the current directory.
ls -la: Lists all files in the current directory with additional information.

Shell Special Commands

!!: Executes the last command.
Caution when using
exit: Exits the current shell.

System Information

cal: Shows a calendar for the current month. The parameter "-w" adds week numbers.
date: Shows the current date and time.
date -R: Shows the current date and time in the RFC-5322 format.
date -u: Shows the current date and time as Coordinated Universal Time (UTC).
hostname: Shows the hostname of the system.
hostname -i: Shows the IP address of the system.
last reboot: Shows a list with the last system reboots.
uname -a: Shows system and kernel information like operating system name and version, machine name and kernel release.
uptime -p: Shows how long the system has been running.
uptime -s: Shows the date and time since the system is running.

Users and Groups

cat /etc/group: Shows the file "/etc/group" with all group names and group IDs.
cat /etc/passwd: Shows the file "/etc/passwd" with all user names and user IDs.
groupadd [GROUP]: Creates a new group with the specified [GROUP] name.
Execute with sudo
groupdel [GROUP]: Removes the group specified by [GROUP].
Execute with sudo / Caution when using
groups: Shows the current group names.
id: Shows user and group information for the current user.
id -un: Shows the own user name. Same as "whoami".
id [USER]: Shows user and group information for the specified [USER].
last: Shows a list with the last logged in users.
useradd [USER]: Creates a new user with the specified [USER] name.
Execute with sudo
userdel [USER]: Removes the user specified by [USER].
Execute with sudo / Caution when using
usermod -aG [GROUP] [USER]: Adds a [USER] to the specified [GROUP]. Without option "-a" all other groups of the user will be replaced with the new group!
Execute with sudo / Caution when using
users: Shows the currently logged in users.
w: Shows a list with the currently logged in users and their activity.
who: Shows a list with the currently logged in users.
who -b: Shows the date and time of the last system boot.
whoami: Shows the own user name. Same as "id -un".

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