> ## Documentation Index
> Fetch the complete documentation index at: https://docs.opus-host.de/llms.txt
> Use this file to discover all available pages before exploring further.

# Linux CLI Cheatsheet for Opus Host VPS Users

> The Linux commands you'll actually use on your Opus Host VPS: files, permissions, processes, services, networking, and package management.

A short reference of the commands you will use daily on your VPS. Not exhaustive, just the ones that come up.

## Files and directories

```bash theme={null}
ls               # list files in current directory
ls -lah          # long format, all files, human-readable sizes
cd /path/to/dir  # change directory
cd ~             # go to your home directory
pwd              # print current directory
mkdir foo        # make directory
rm file          # remove file
rm -rf dir       # remove directory and contents (careful!)
cp src dst       # copy
mv src dst       # move or rename
touch file       # create empty file / update timestamp
cat file         # print file contents
less file        # scroll through file (q to quit)
tail -f log      # follow a log file as it grows
head -n 20 file  # first 20 lines
find . -name "*.log"  # find files by name
```

## Permissions and ownership

```bash theme={null}
chmod 644 file           # rw-r--r--
chmod 755 script.sh      # rwxr-xr-x (executable)
chmod +x script.sh       # make executable
chown user:group file    # change owner and group
sudo chown -R www-data:www-data /var/www
```

## Users and sudo

```bash theme={null}
whoami                   # current username
id                       # user ID and groups
sudo command             # run one command as root
sudo -i                  # interactive root shell
adduser alice            # create user (see User Management)
```

See [User Management](/vps/user-management) for the full flow.

## Processes

```bash theme={null}
ps aux                   # all running processes
top                      # live process view (q to quit)
htop                     # nicer top (sudo apt install htop)
kill <pid>               # gracefully stop a process
kill -9 <pid>            # force kill
pgrep -af nginx          # find PIDs by name
```

## Services (systemd)

```bash theme={null}
sudo systemctl status nginx
sudo systemctl start nginx
sudo systemctl stop nginx
sudo systemctl restart nginx
sudo systemctl enable nginx     # start on boot
sudo journalctl -u nginx -f     # follow service logs
```

See [systemd Services](/vps/systemd-services).

## Disk and memory

```bash theme={null}
df -h            # disk space by mount
du -sh /var/*    # size of each directory in /var
free -h          # RAM and swap usage
uptime           # load average
```

## Networking

```bash theme={null}
ip a             # network interfaces and IPs
ss -tulpn        # listening ports and processes
ping example.com
curl -I https://example.com   # HTTP headers
dig example.com               # DNS lookup
```

## Package management (apt)

```bash theme={null}
sudo apt update              # refresh package index
sudo apt upgrade -y          # install available upgrades
sudo apt install nginx -y    # install a package
sudo apt remove nginx        # remove a package
sudo apt autoremove -y       # remove unused deps
apt search nginx             # search for a package
```

See [Package Updates](/vps/package-updates).

## Downloading files

```bash theme={null}
curl -O https://example.com/file.tar.gz
wget https://example.com/file.tar.gz
```

## Archives

```bash theme={null}
tar czf out.tar.gz dir/      # create gzip archive
tar xzf out.tar.gz           # extract gzip archive
unzip file.zip
```

## SSH and file transfer

```bash theme={null}
ssh alice@your.vps.ip
scp local.txt alice@your.vps.ip:/home/alice/
rsync -avz local/ alice@your.vps.ip:/home/alice/remote/
```

## Editing files

```bash theme={null}
nano file    # beginner-friendly editor. See Nano Cheatsheet
vim file     # if you already know vim
```

See [Nano Cheatsheet](/reference/nano-cheatsheet).

## History and shortcuts

```bash theme={null}
history         # command history
!!              # repeat last command
!123            # repeat command number 123 from history
Ctrl+R          # search backwards through history
Ctrl+C          # cancel running command
Ctrl+D          # log out / close shell
Ctrl+L          # clear screen
```

<Tip>
  When in doubt, `man <command>` gives you the manual page. Press `q` to quit.
</Tip>