developer reference

Linux cheat sheet

A practical Linux reference with search, one-click copy and printable PDF output.

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43
commands
7
categories
0
dependencies

43 commands visible

Files

8 commands
ls -lah

Lists files with details, hidden files and human-readable sizes

Filesafe
Practical example 
ls -lah
ls -lah /etc
find <path> -name "<pattern>"

Finds files by name or attributes

Filesafe
Practical example 
find . -name "*.py"
find /var -mtime -7 -type f  # modified in the last 7 days
find . -size +10M
cp -r <src> <dst>

Copies files or directories

Filesafe
Practical example 
cp file.txt backup.txt
cp -r src/ dst/
mv <src> <dst>

Moves or renames files

Filesafe
Practical example 
mv old.txt new.txt
mv *.log /var/logs/
rm -rf <path>

Removes files or directories, irreversible

Filecaution

Permanently deletes files and directories. Verify the resolved path before using -rf.

Practical example 
rm file.txt
rm -rf ./tmpdir
mkdir -p <path>

Creates directories (-p also creates parents)

Filesafe
Practical example 
mkdir -p /opt/myapp/logs
ln -s <target> <link>

Creates a symbolic link

Filesafe
Practical example 
ln -s /opt/myapp /usr/local/bin/myapp
du -sh <path>

Size of files or directories

Filesafe
Practical example 
du -sh /var/log
du -sh * | sort -h  # sort by size

Text processing

8 commands
cat <file>

Prints file content

Text processingsafe
Practical example 
cat /etc/hosts
cat file1 file2 > merged.txt
grep -rn "<pattern>" <path>

Searches patterns in files/directories

Text processingsafe
Practical example 
grep -rn "TODO" ./src
grep -v "^#" config.txt  # exclude comments
grep -E "error|warn" app.log
sed 's/<old>/<new>/g' <file>

Replaces text in files with a stream editor

Text processingsafe
Practical example 
sed 's/http/https/g' urls.txt
sed -i 's/foo/bar/g' file.txt  # edit in place
awk '{ print $1 }' <file>

Processes and transforms text column by column

Text processingsafe
Practical example 
awk '{print $1, $3}' data.txt
awk -F: '{print $1}' /etc/passwd  # list users
sort

Sorts lines (--numeric-sort, --reverse, -u unique)

Text processingsafe
Practical example 
sort file.txt
sort -k2 -n data.txt
sort -u file.txt  # remove duplicates
cut -d'<sep>' -f<n>

Extracts columns from delimited text

Text processingsafe
Practical example 
cut -d: -f1 /etc/passwd
cut -d',' -f2,4 data.csv
tail -f <file>

Shows last N lines; -f follows in real time

Text processingsafe
Practical example 
tail -100 app.log
tail -f /var/log/syslog
wc -l <file>

Counts lines (-l), words (-w), characters (-c)

Text processingsafe
Practical example 
wc -l access.log
grep "ERROR" app.log | wc -l

Processes

6 commands
ps aux

Lists all processes with CPU/RAM usage

Processessafe
Practical example 
ps aux
ps aux | grep nginx
top

Interactive real-time process monitor

Processessafe
Practical example 
top
top -u www-data  # filter by user
kill -<signal> <pid>

Sends a signal to a process

Processescaution

Verify the PID. Prefer SIGTERM; SIGKILL prevents cleanup and may lose unsaved data.

Practical example 
kill -9 1234  # SIGKILL: force termination
kill -15 1234  # SIGTERM: request a clean shutdown
killall <name>

Kills all processes with that name

Processescaution

Targets all matching process names. Verify the name and signal first.

Practical example 
killall nginx
nohup <cmd> &

Runs a command that survives logout

Processessafe
Practical example 
nohup python3 server.py &
nohup ./script.sh > out.log 2>&1 &
jobs

Lists background jobs in the session

Processessafe
Practical example 
jobs
bg %1  # send to the background
fg %1  # return to the foreground

Permissions

4 commands
chown <user>:<group> <file>

Changes owner of files/directories

Permissionssafe
Practical example 
chown www-data:www-data /var/www
chown -R enzo:enzo /opt/myapp
sudo <cmd>

Runs a command as superuser

Permissionssafe
Practical example 
sudo apt update
sudo -u postgres psql  # as another user
sudo visudo

Safely edits the sudoers file

Permissionssafe
Practical example 
sudo visudo

Network

6 commands
curl -X <METHOD> <url>

Transfers HTTP/FTP data from the command line

Networksafe
Practical example 
curl -X GET https://api.example.com/users
curl -X POST -H "Content-Type: application/json" -d '{"k":"v"}' <url>
curl -O https://example.com/file.zip
ssh <user>@<host>

Remote SSH connection

Networksafe
Practical example 
ssh enzo@192.168.1.100
ssh -i ~/.ssh/id_rsa user@server
ssh -L 8080:localhost:80 user@server  # tunnel
scp <src> <user>@<host>:<dst>

Copies files over SSH

Networksafe
Practical example 
scp file.txt enzo@server:/home/enzo/
scp -r ./dist user@server:/var/www/
ss -tulnp

Shows listening ports with processes

Networksafe
Practical example 
ss -tulnp
ss -tulnp | grep 8080
ip addr

Shows network interfaces and IP addresses

Networksafe
Practical example 
ip addr
ip addr show eth0
ping -c 4 <host>

Checks connectivity with a host

Networksafe
Practical example 
ping -c 4 google.com
ping -c 1 192.168.1.1

Disk

4 commands
df -h

Free space per filesystem

Disksafe
Practical example 
df -h
df -h /var
lsblk

Lists block devices and partitions

Disksafe
Practical example 
lsblk
lsblk -f  # include filesystems
tar -czf <archive.tar.gz> <path>

Creates a gzip-compressed archive

Disksafe
Practical example 
# create
tar -czf backup.tar.gz /opt/myapp
# extract
tar -xzf backup.tar.gz -C /tmp
# list archive contents
tar -tzf backup.tar.gz
rsync -avz <src> <dst>

Efficient file synchronization, local or SSH

Disksafe
Practical example 
rsync -avz ./dist/ user@server:/var/www/
rsync -avz --delete src/ dst/

System

7 commands
uname -a

Kernel version and system info

Systemsafe
Practical example 
uname -a
uptime

Uptime and load average

Systemsafe
Practical example 
uptime
uptime -p  # human-readable
systemctl <action> <service>

Manages systemd services

Systemsafe
Practical example 
systemctl start nginx
systemctl enable nginx
systemctl status nginx
systemctl restart nginx
journalctl -u <service> -f

systemd logs for a service, follow mode

Systemsafe
Practical example 
journalctl -u nginx -f
journalctl -u nginx --since "1 hour ago"
env

Shows environment variables

Systemsafe
Practical example 
env
env | grep PATH
export VAR=value

Sets an environment variable for the session

Systemsafe
Practical example 
export NODE_ENV=production
export PATH="$PATH:/opt/myapp/bin"
crontab -e

Edits current user cron jobs

Systemsafe
Practical example 
# format: minute hour day month weekday command
0 2 * * * /opt/backup.sh  # every night at 02:00
*/5 * * * * /opt/check.sh  # every 5 minutes

Continue with

How to use this Linux cheat sheet

Why should files and directories use different permissions?

Directories require the execute bit to traverse them. Applying 644 recursively makes directories inaccessible; set directory and file permissions separately for your use case.

Can I print this sheet as a PDF?

Use Print PDF. The printable version includes all commands and practical examples, including sections hidden by a search.

Can I use it locally?

Yes. Serve the static files with a local HTTP server. Search, filters and copying run in your browser; the Regex tester requires a worker-enabled HTTP context.

Official documentation: Linux