Sysadmin tools
Converters, calculators and cheats for people who run servers.
Chmod Calculator
Octal, symbolic and special bits both ways, with plain-English meaning and warnings.
Runs in your browser
Kill Process on Port
Type a port and get the exact command to find and kill what is using it, on Windows, Linux and macOS.
Runs in your browser
Data Transfer Calculator
Convert Mbps to MB/s, decimal to binary units, and get real transfer times.
Runs in your browser
Reading in this category
ChatGPT desktop for Linux: the .deb adds an OpenAI apt repo
OpenAI shipped a native Linux ChatGPT app on 11 August as DEB and RPM. The DEB writes an OpenAI repository into apt, and the bundled Codex runs commands.
Seagate 50TB HAMR drives: 2028, not 2027
Seagate says 50TB-class drives qualify in late 2027 and ship after. The number that hits your budget first is price per exabyte, up around 10 percent.
New York pauses 50MW+ data centers: what changes
New York is the first US state to pause new hyperscale data centers. Where the 50MW line falls, what is carved out, and whether any of it reaches your bill.
Linux file permissions explained: rwx and 755
How Linux file permissions work: the rwx triads, owner group and other, octal modes like 644 and 755, and the execute bit on directories that quietly breaks things.
MB vs MiB: why your 1 TB drive shows up as 931 GB
MB vs MiB, KB vs KiB: the difference between decimal (1000) and binary (1024) units, why a 1 TB drive reads as 931 GiB, and where Mbps and bytes part ways.
How to change file permissions with chmod
Change file permissions with chmod: chmod 644 for files, chmod 755 for scripts and folders, chmod +x to make a file runnable. The numbers explained, with examples.
How to manage services with systemctl
Manage Linux services with systemctl: status, start, stop, restart, enable at boot, and journalctl for logs. The commands you need and what enable --now does.
How to find files with find on Linux
Find files on Linux with find: by name, type, size or age, then act with -delete or -exec. The syntax, real examples, and how to delete matches safely.
How to extract and create tar.gz archives (tar)
Extract a tar.gz with tar -xzf and create one with tar -czf. What the x, z, f, c flags mean, how to target a folder with -C, and the bz2 and xz variants.
How to kill the process using a port on Linux
Address already in use on Linux? Find the PID with lsof -i or ss -ltnp, then kill it (kill -9 last). Steps, a fuser one-liner, and SIGTERM vs SIGKILL.
How to kill the process using a port on Windows
Port already in use on Windows? Find the PID with netstat -ano, then taskkill /PID /F to free it. Step by step, with the PowerShell one-liner and the gotchas.