Technology with a focus on Open Source
We already covered how Linux executes files and how to run ARM binaries “natively” in Linux in the last two posts. We ended up running a whole ARM root filesystem transparently in a chroot jail using QEMU user mode and binfmt_misc support. Now that we have that covered, nothing prevents us from applying that to …
What? you can do that in Linux? It turns out you can! First, let’s see it in action. Here I retrieve a binary from my Raspberry Pi which is an ARM binary and execute it in my x86_64 machine transparently. If you try to do this… it won’t work right away.
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$ ./echo zsh: exec format error: ./echo |
First …
What happens when a file gets executed in Linux? What does it mean that a file is executable? Can we only execute compiled binaries? What about shell scripts then? If I can execute shell scripts, what else can I execute? In this article we will try to answer those questions. What involves executing a …
This is a little compilation of some useful configuration options and basic methods to debug a Linux kernel. There is good documentation in kernel.org and elsewhere but back when I was learning these things I felt that there are few places where you can get a high level overview. We will go through more advanced …
How much space is this file taking from my hard drive? How much free space do I have? How many more files can I fit in the remaining free space? The answer to these questions seems obvious. We all have an instinctive understanding of how filesystems work, and we often picture storing files in disk …
dutree is a command line tool to analyze disk usage. Features coloured output, according to the LS_COLORS environment variable. display the file system tree ability to aggregate small files ability to exclude files or directories ability to compare different directories fast, written in Rust This tool is a mix between tree and durep, which we already …
To complement the last BTRFS tool btrfs-snp (which allows us to schedule snapshots), I would like to share a new tool to synchronize them locally or remotely to achieve efficient data redundancy. With btrfs-snp we can replicate our BTRFS snapshots in a different BTRFS system, and have a second copy of our versioned subvolume in …
I would like to share another wrapper based on the pv command ( because we love progress bars!! ). As part of my work in NextCloudPi, I am constantly copying images to an SD card to test the latest build. The classic Linux way of doing this is by using the dd command
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# dd bs=4M if=NextCloudPi_02-06-18.img of=/dev/sdd && sync |
We …
To complement the last BTRFS tool btrfs-du, I would like to share a simple script for creating BTRFS snapshots that plays well with cron and systemd timers. This allows us to easily automate snapshot creation. I was inspired by btrfs-snap by Birger Monsen. Usage btrfs-snp can be run manually, or summoned from cron. Invoke without …
Today I want to share a simple way to check the state of our BTRFS snapshots. Usage
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# btrfs-du /path/ |
If path is omitted, it will default to / . We can list easily our snapshots, plus have a clear view of how much data they have in common and how much total overhead are we holding. …