VPP.dk — Linux Tricks

Serve the current directory over HTTP for quick file sharing on the LAN — requires only Python 3.

bash

$ python3 -m http.server 8080 # On a specific interface: python3 -m http.server 8080 --bind 0.0.0.0 # Then access from another machine: curl http://<your-ip>:8080/

quickserve 2026-04-19

Networking Scripting

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Monitor network traffic per interface

Watch live bandwidth usage broken down by network interface using nload or ifstat.

bash

$ # Using nload (apt install nload): nload eth0 # Without extra tools — poll /proc/net/dev: watch -n 1 'cat /proc/net/dev | column -t'

netwatch 2026-04-19

Networking System Info

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Create a timestamped backup of a file

Before editing a config, make a dated backup with a one-liner. The $(date) sub-shell appends the current timestamp.

bash

$ cp nginx.conf nginx.conf.$(date +%Y%m%d_%H%M%S).bak # Backup and keep last 5 only: cp important.conf important.conf.$(date +%Y%m%d).bak ls -t important.conf.*.bak | tail -n +6 | xargs rm -f

backupbro 2026-04-19

File Management Scripting

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Count lines / words / bytes in a file

wc is the Swiss Army knife for file statistics. Combine flags or chain with other commands.

bash

$ wc -l file.txt # lines wc -w file.txt # words wc -c file.txt # bytes # Count non-empty lines: grep -c . file.txt # Total lines across multiple files: wc -l *.log | tail -1

wordcounter 2026-04-19

Text Processing

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Show all running services

List all systemd services and their current status on modern Linux systems.

bash

$ systemctl list-units --type=service --state=running # Full list including inactive: systemctl list-units --type=service

systemd_fan 2026-04-19

Process Management System Info

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Repeat last command as root

Forgot to sudo? Run the previous command with root privileges without re-typing it.

bash

$ sudo !!

lazyadmin 2026-04-19

Scripting

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List all environment variables sorted

Print every environment variable in alphabetical order — handy when debugging missing config or checking what a script will see.

bash

$ printenv | sort # Or just search for a specific one: printenv | grep -i path

envhunter 2026-04-19

Scripting System Info

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Check open ports on the system

List all listening TCP/UDP ports and the process that owns them.

bash

$ # All listening sockets + process names: ss -tulnp # Or with netstat (older systems): netstat -tulnp # Check if a specific port is open: ss -tulnp | grep ':443'

netadmin99 2026-04-19

Networking System Info

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Replace text in multiple files

Use sed with find to do a batch search-and-replace across many files at once.

bash

$ # Replace 'foo' with 'bar' in all .conf files: find /etc -name '*.conf' -exec sed -i 's/foo/bar/g' {} + # Preview changes first (dry-run): grep -rl 'foo' /etc/*.conf

sedmaster 2026-04-19

File Management Text Processing

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SSH tunnel — forward a remote port locally

Access a service running on a remote server as if it were local. Useful for databases, dev servers, etc.

bash

$ # Forward remote port 5432 to local port 5432: ssh -L 5432:localhost:5432 user@remote-host # Persistent background tunnel (no shell): ssh -fNL 8080:localhost:80 user@remote-host

tunnelvision 2026-04-19

Networking SSH & Remote

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