Linux Commands

Linux Commands

Here are some basic linux commands. Please be aware that depending on your distribution they might me slightly different or non existent.

File and directory management

command	description
ls	list directory contents
cd	change directory
pwd	print working directory
cp	copy files and directories
mv	move or rename files and directories
rm	remove files or directories
mkdir	make directories
rmdir	remove empty directories
touch	change file timestamps or create empty files
find	search for files in a directory hierarchy
locate	find files by name
tree	display directories in a tree like format
chmod	change file permissions
chown	change file owner and group
chgrp	change group ownership
stat	display file or file system status

File viewing and editing

command	description
cat	concatenate and display file content
tac	concatenate and display file content in reverse
more	view file content interactively (page by page)
less	view file content interactively (scrollable)
head	output the first part of a file
tail	output the last part of a file
nano	text editor in terminal
vim or vi	advanced text editor in terminal
emacs	text editor in terminal
grep	search text using patterns
sed	stream editor for filtering and transforming text
awk	pattern scanning and processing language
cut	remove sections from each line of files
sort	sort lines of text files
uniq	report or omit repeated lines

Process Management

command	description
ps	report a snapshot of current processes
top	display linux tasks
htop	interactive process viewer (advanced top)
kill	send a terminate signal to a process
killall	terminate process by name
bg	resume a suspended background job
fg	bring a job to the foreground
jobs	list active jobs
nice	run a program with modified scheduling priority
renice	alter priority of running processes
uptime	show how long the system is up and running
time	measure program running time

Disk management

command	description
df	report file system disk space usage
du	estimate file space usage
fdisk	partition table manipulator
lsblk	list information about block devices
mount	mount a file system
umount	unmount a file system
parted	partition table manipulator
mkfs	create a file system
fsck	file system consistency check and repair
blkid	locate/print block device attributes

Networking

For the networking command I gonna create a seperate entry too…

command	description
ifconfig	configure network interfaces
ip	show/manipulate routing, devices and tunnels
ping	send ICMP echo requests to network host
netstat	network statistics
ss	socket statistics
traceroute	trace the route packets take to a network host
nslookup	query internet name servers interactively
dig	DNS lookup utility
wget	non-interactive downloader
curl	transfer data with URLs
scp	secure copy files between hosts
ssh	secure shell for remote login
ftp	file transfer protocol client

User and group management

command	description
useradd	add a user
usermod	modify a user
userdel	delete a user
groupadd	add a group
groupdel	delete a group
passwd	modify the user password
chage	change password expiry information
whoami	print the current logged in user
who	show who is logged in
w	show who is logged in and what they are doing
id	display the user and group id
groups	show the user’s groups

System information and monitoring

command	description
uname	print system information
hostname	show or set the system’s hostname
uptime	how long the system has been running
dmesg	boot and system messages
free	display memory usage
top	display linux tasks
vmstat	report virtual memory statistics
lscpu	display information about the CPU architecture
lsusb	list USB devices
lspci	list PCI devices
lshw	list hardware configuration

Archiving and compression

command	description
tar	archive files tar -czf test.tar.gz /directory/path/ → compress files using gzip tar -xzf test.tar.gz → extract gzipped tarball tar -cf test.tar → /directory/path → create a tarball tar -xf test.tar → extract tarball
zip	package and compress files into a ZIP archive
unzip	extract files from a ZIP archive
gzip	compress files using the gzip algorithm
gunzip	decompress files compressed with gzip
bzip2	compress files using the bzip2 algorithm
bunzip2	decompress files compressed with bzip2
xz	compress files using the xz algorithm
unxz	decompress files compressed with xz

Package Management

Debian based (like Ubuntu)

command	description
apt-get	APT package handling utility apt-get install packagename → install a package apt-get update → update package list apt-get upgrade → upgrade installed packages apt-get remove packagename → remove a package
apt-cache	query APT cache apt-cache search packagename → search for a package apt-cache show packagename → show package details

Red Hat based (like Centos, Fedora)

command	description
yum	package manager for RPM based systems yum install packagename → install a package yum update → update installed package yum remove packagename → remove a package
dnf	next generation package manager (CentOS 8+, Fedora) dnf install packagename → install a package dnf update → update installed packages dnf remove packagename → remove a package

General

command	description
rpm	RPM package manager rpm -i packagename.rpm → install an RPM package rpm -e packagename → remove an RPM package
dpkg	Debian package manager dpkg -i packagename.deb → install a Debian package dpkg -r packagename → remove a Debian package

System services and daemon management

command	description
systemctl	control the systemd system and service manager systemctl start servicename → start a service systemctl stop servicename → stop a service systemctl restart servicename → restart a service systemctl enable servicename → enable a service to start on boot systemctl disable servicename → disable a service from starting on boot systemctl status servicename → check service status
service	older service management command (used in non systemd systems) service servicename start → start a service service servicename stop → stop a service service servicename restart → restart a service service servicename status → check service status

Scheduling tasks

command	description
cron	daemon for running scheduled commands crontab -e → edit cron jobs for the current user crontab -l → list the current user’s cron jobs crontab -r → remove the current user’s cron jobs
at	run commands at a specified time at 06:00 → schedule a command to run at 6:00 o’clock
batch	run commands when the system load is low
sleep	delay for a specified time sleep 6s → sleep for 6 seconds

File permissions and security

command	description
chmod	change file permissions
chown	change file owner and group
chgrp	change the group ownership of a file
umask	set default permissions for new files
setfacl	set file access control lists (ACL)
getfacl	get file access control lists
sudo	execute a command as another user (usually root)
visudo	edit the sudoers file safely
passwd	change a user’s password
sudoers	manage sudo access for users
gpasswd	administer group password
ss	display socket statistics (for secure network connections)

System backup and restore

command	description
rsync	remote file and directory synchronization rsync -avz source destination → synchronize files rsync -avz -e ssh source user@remote:/destination/ → sync over SSH
cpio	copy files to and from archives
dd	low-level copying and backup of entire filesystems dd if=/dev/sda of=/path/backup.img → backup a disk or partition dd if=/path/backup.img of=/dev/sda → restore a disk or partition

System Diagnostics and Troubleshooting

command	description
dmesg	print the kernel ring buffer messages system boot and hardware related messages
journalctl	query and view logs from systemd’s jourmal
strace	trace system calls and signals strace commandname → trace a command’s system call
lsof	list open files lsof files → show processes using a specific file
vmstat	report virtual memory statistics
iostat	report CPU and I/O statistics
mpstat	report CPU usage statistics
pidstat	report statistics by process
free	display memory usage
uptime	how long the system has been running
watch	execute a program periodically – showing output watch -n 1 free → watch memory usage every second
lshw	list hardware configuration
htop	interactive process viewer
netstat	network statistics (replaced by ss)
ss	show socket statistics

Networking & Remote Management

command	description
ifconfig	configure network interfaces (replaced by ip)
ip	a more modern alternative for managing network interfaces and routing ip addr → show ip addresses ip link → show or manipulate network interfaces ip route → show or manipulate routing tables
ss	show socket statistics
nmap	network exploration tool
telnet	user interface to the telnet protocol
nc	network utility for reading and writing from network connections netcat nc -l -p 1234 → listen on port 1234 nc host port → connect to a host and port
iptables	administration tool for IPv4 packet filtering and NAT
firewalld	frontend for managing firewall rules (Fedora/CentOS)
ufw	uncomplicated firewall ufw enable → enable firewall ufw allow port → allow traffic on a specific port
tcpdump	command line packet analyzer
curl	transfer data from or to a server using various protocols
wget	download files from the web
scp	secure copy over SSH scp test.txt user@remotemachine:/path → copy file to remote machine
rsync	remote file and directory synchronization rsync -avz /path/ remotemachine:/path → sync directories between 2 machines

Text Processing Utilities

command	description
grep	search for patterns within files grep ‘pattern’ file.txt → search for a pattern in a file grep -r ‘pattern’ /dirname/ → recursively search for a pattern
sed	stream editor for filtering and transforming text sed ‘s/old/ne/g’ file.txt → replace old by new globally
awk	a powerful text processing language awk ‘{print $1} file.txt → print the first column of each line in a file
cut	remove sections from each line of a file cut -d ‘:’ -f 1 /etc/passwd → print the first field of each line delimited by “:”
sort	sort lines of text files sort file.txt → sort file content in ascending order
uniq	report or omit repeated lines in a file sort file.txt | uniq → sort an remove duplicate lines
tee	read from standard input and write to standard output and files echo “text” | tee file.txt → write to file and show output on screen
tr	translate or delete characters echo “hello” | tr ‘a-z’ ‘A-Z’ → convert lowercase to upercase letters
paste	merge lines of files paste file1.txt file2.txt → combine lines of file1 and file2 side by side
wc	word, line, character and or byte count wc -l file.txt → count lines in a file wc -w file.txt → count words in a file

System shutdown and reboot

command	description
shutdown	shut down a system shutdown -h now → immediately shut down the system shutdown -r now → immediately reboot the system shutdown -h +10 → shut down after 10 minutes
reboot	reboot the system
halt	halt the system immediately
poweroff	power off the system
init	change the runlevel (old-style system manager) init 0 → shutdown init 6 → reboot

File system mounting and management

command	description
mount	mount a file system mount /dev/sda1 /mnt → mount partition to a directory
umount	umount a file system umount /mnt → unmount the file system mounted at /mnt
fstab	file system table configuration file for mounting file systems
blkid	display block device attributes
fsck	check and repair a file system fsck /dev/sda1 → check and repair /dev/sda1

Filesystem permissions and security

command	description
chmod	change file permissions chmod 755 file.txt → give read write and execute permissions to owner and read/execute permissions to others
chown	change file owner and group chown user:group file.txt → change owner and group of a file
chgrp	change group ownership of a file chgrp group file.txt → change the group of a file
umask	set default permissions for new files umask 022 → set default permissions for newly created files to 755
setfack	set access control lists (ACL) for file permissions
getfacl	get access control lists (ACL) for file permissions

Docker (containerization and orchestration)

command	description
docker	docker command line (CLI) for managing containers
docker run image	run a container from an image
docker ps	list running containers
docker ps -a	list all containers including stopped ones
docker build -t imagename .	build an image from a dockerfile
docker exec -it container_id bash	start an interactive bash shell inside a running container
docker stop container_id	stop a container
docker rm container_id	remove a container
docker logs container_id	view logs of a container
dock images	list available images
docker rmi imagename	remove an image
docker network ls	list docker networks
docker-compose	manage multi-container docker applications
docker-compose up	start up a multi-container environment
docker compose down	stop and remove containers created by docker-compose
docker-compose logs	view logs from containers managed by docker-compose

Kubernetes (k8s) (containerization and orchestration)

command	description
kubectl	command line tool for interacting with Kubernetes clusters
kubectl get pods	list pods in the current namespace
kubectl get nodes	list nodes in the cluster
kubectl get services	list services in the cluster
kubectl apply -f file.yaml	apply configuration from a file
kubectl create -f file.yaml	create a resource from a file
kubectl delete -f file.yaml	delete a ressource defined in a file
kubectl exec -it podname –bash	execute a command inside a pod (ex. open a shell)
kubectl logs podname	view the logs of a pod
kubectl describe pod podname	get detailed information about a pod
kubectl scale deployment deploymentname –replicas=number	scale a deployment to the desired number of replicas
kubectl rollout restart deployment deploymentname	restart a deployment
kubectl port-forward pod podname localport:remoteport	forward a port from a pod to localhost

Helm (containerization and orchestration)

command	description
helm	Kubernetes package manager for deploying applications
helm install releasename chartname	install a helm chart
helm upgrade releasename chartname	upgrade a helm release
helm list	list all helm releases
helm delete releasename	delete a helm release
helm search chartname	search for a helm chart

Automation and configuration management

Ansible

command	description
ansible	automation tool for configuration management
ansible all -m ping	ping all hosts defined in the inventory
ansible-playbook playbook.yml	run an ansible playbook
ansible -m command -a ‘command’ host	run a single command on a target host
ansible-playbook –check playbook.yml	dry run a playbook to see what would change
ansible-playbook –limit host playbook.yml	run a playbook on a specific host or group
ansible-playbook –extra-vars “key=value”	pass extra variables to a playbook

Terraform

command	description
terraform	infrastructure as code tool for provisioning and managing cloud ressources
terraform init	initialize a working directory for terraform configuration
terraform plan	show an execution plan (what changes would be made)
terraform apply	apply the changes described in a terraform configuration
terraform destroy	destroy infrastructure created by terraform
terraform validate	validate the configuration files
terraform show	show the current state of the infrastructure

Puppet

command	description
puppet	configuration management tool
puppet apply manifest.pp	apply a puppet manifest locally
puppet agent —test	test the puppet agent
puppet resource	show the current state of resources (files, services, etc.)

CI/CD tools and commands

Jenkins

command	description
jenkins	continous integration tool
java -jar jenkins.war	start jenkins from a war file access jenkins trough http://localhost:8080 by default

GitLab CI

command	description
.gitlab-ci.yml	configuration file for GitLab CI/CD pipelines
gitlab-runner register	register a new runner with GitLab
gitlab-runner run	run the Gitlab Runner to process jobs

GitHub Actions

command	description
Info	GitHub Actions uses YAML configuration files typically located in .github/workflows/
actions/checkout@v2	checkout the repository code in your CI pipeline
actions/setup-node@v2	setup Node.JS for use in a pipeline
docker/setup-buildx-action@v1	set up docker buildx for building multi platform images

Cloud Services

AWS CLI (Amazon Web Services)

command	description
aws	command line tool for managing AWS services
aws configure	configure AWS CLI with your credentials
aws s3 cp file.txt s3://bucketname/	copy a file to an S3 bucket
aws ec2 describe-instances	descripe EC2 instances
aws ec2 start-instances –instance-ids id	start an EC2 instance
aws ec2 stop-instances –instance-ids id	stop an EC2 instance
aws s3 sync	sync directories with an S3 bucket

Azure CLI (Microsoft)

command	description
az	command line tool for managing Azure services
az login	log in to your Azure account
az vm list	list all virtual machines
az vm start –name vmname –resource-group resourcegroup	start an Azure VM
az storage blob upload	upload files to an Azure blob storage
az group create	create a new resource group in Azure AD

Google Cloud SDK

command	description
gcloud	command line tool for Google cloud platform
gcloud auth login	log in to Google cloud
gcloud compute instances list	list compute instances
gcloud compute instances stop instancename	stop a Google cloud VM instance
gcloud ap browse	open the current Google app engine application in a browser

Logging and Monitoring

Prometheus

command	description
prometheus	open source system monitoring and alerting toolkit start prometheus server (usually as a background service)
prometheus –config.file=configfile	start prometheus with a specific config file

Grafana

command	description
grafana-cli	command line interface for managing Grafana plugins
grafana-cli plugins install pluginname	install a plugin in Grafana

ELK Stack (Elasticsearch, Logstash, Kibana)

command	description
elasticsearch	search engine for logging and data analytics
curl -XGET ‘localhost:9200/_cluster/health?pretty’	get cluster health status
logstash	server side data processing pipeline
logstash -f configfile	run logstash with the specified configuration file
kibana	web interface for visualizing Elasticsearch data Kibana is generally access through web on http://localhost:5601