Sysadmin

🧹 My Messy Linux Box As year passes, my Linux system, over the time, starts to get a little… Messy. My ~/Downloads directory is a digital dumping ground. It’s a collection of ISOs, test scripts, and those huge multi-gigabyte Virtual Machine images I need to test once and then forget about. Add to that ~/Pictures/Screenshots, which is overflowing with thousands of quick snaps I’ll never look at again. Disk space is cheap nowadays, but I like to have things nice and clean. I could go in and manually clean it… But who remembers to do that ? ...

💭 What ? Imagine a web server that only starts when someone actually tries to access it. Or a database that spins up only when a query comes in: this is the magic of socket activation. The concept is not new, as old-school sysadmins may are used to see something like inetd or xinetd for on-demand service activation in the past. As some cool projects like cockpit have already started using this little-known feature, in this blog post we’ll see the basics and try to get familiarity with the tooling. ...

💾 Intro I just found a very cheap SD card on an online store and since I know that there are some fake around, I wanted to quickly test if its size and speed respect the specs. Edit: after first publish, a kind reader noticed me that The F3 tools are a perfect fit for the same task and that’s right; if you want to follow a manual path and learn something in the journey, continue reading… ...

I have a binary file with data stored as two-byte big-endian 16-bit words. We need to extract the values in the file and print them in decimal ASCII format, so to obtain numbers in the 0-655535 range. let’s create the sample file: $ echo -en "\x01\x02\x03\x04\x05\x06\x07\x08" > file.bin and show its content in binary form: $ hexdump -C file.bin 00000000 01 02 03 04 05 06 07 08 |........| 00000008 to get the desired output we can use the powerful, but little documented format string option of hexdump: ...