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#!/usr/bin/env bash
#
# A fast, simple and small, streaming archiver
#
# Usage similar to cpio but without path length and file size limits. It is
# intentionally very basic and just groups files (or splits them apart). It
# only supports extraction of all files (no individual file access) and has no
# handling of special file types outside of symlinks. It will however restore
# modification times and permissions.
#

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SCO cpio (newc) 9 EiB file size extension

The cpio newc format only supports individual files up to a 4 GiB limit. SCO extended the newc format to support much larger files (up to around 9 EiB).

TL;DR

• SCO archives are normal newc unless a file entry is too large.
• For 'large files', the full size is stored as a second NUL‑terminated string

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GNU cpio and inode truncation considerations

The following explains how inode truncation in classic cpio formats (odc and newc) interacts with hardlinked files, and under what conditions you may encounter problems.

TL;DR

Unless you are still using cpio for full system backups, this is probably a non‑issue. Nonetheless, to ensure correct hardlink preservation with GNU cpio:

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#!/bin/sh
# A simple script to locate files associated with a software install
# (Should work on Linux, BSD and macOS [13+])
#
# This finds files whose metadata changed (which, for installed files,
# typically corresponds to their creation) around the same time as a
# reference file or an executable found in $PATH, within common install
# locations.
#
# It works by noting the UNIX Change time (ctime) of the reference file and

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Running RAR for Linux on arm64

TL;DR This guide shows how to run the x86_64 Linux RAR binary on arm64 using QEMU user-mode or FEX¹, and compares their performance. If you do not want to read further, simply install either of them via your package manager and then run the script included with this gist, to automatically download, configure and install RAR.

¹ FEX only adds about 13% overhead.

Intro

RAR is a strong archiving option on Linux when you need features other formats do not provide, such as built‑in recovery records, archive‑level deduplication, robust multi‑volume handling, advanced filters, archive content search & manipulation, strong encryption, etc. [Full comparison with other Linux archivers]

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Tar vs Rar vs 7‑Zip vs Info‑ZIP on Linux

TL;DR

• tar: Full Linux filesystem metadata and special file support.
• rar: Extensive feature set: permissions, ownership, recovery, deduplication, filtering, archive content manipulation, strong encryption, etc.
• 7z: Strong encryption where open source is a requirement.
• zip: Maximum compatibility.

Note: They are actually all widely supported for extraction by common libaries. You will not realistically find a modern system, configured for desktop use, that cannot open all of these but zip will be less confusing to non-technical users and has wider support on legacy, mobile and embedded platforms out of the box.

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Rar vs 7z on Linux

TL;DR

• rar: More feature‑rich for archival integrity and file manipulation. Creation is proprietary and requires a license but it is fully free and open for extraction.
• 7z: Fully open‑source and free to use for both creation and extraction. It can sometimes have marginally better compression ratios.

Rar is preferable to 7z on Linux when you need features 7‑Zip does not provide, such as built‑in recovery records, archive‑level deduplication, more robust multi‑volume handling, stronger resilience against corruption, advanced filters and preservation of basic UNIX ownership and permissions. If you don't need those, or fully open source is a must, then 7z is a reasonable option.

Note: Both actually have pretty equal support for extraction by a third party. You will not realistically find a system that can open .7z but not .rar, or vice versa.

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Preserving UNIX (Linux) File Permissions and Ownership in .7z and .zip Archives

When possible, native *nix formats like tar are the best choice for backups. However, there are cases where other formats may be preferable due to their features. For example, specific compression options or non‑solid compression that allow faster access to individual files. In these situations, common tools such as 7‑Zip (with Windows heritage) may not store UNIX meta data correctly. By combining small, easy‑to‑create helper scripts with your backup archives, you can preserve metadata. Here are three short scripts that can be generated via shell one-liners:

• perms.sh → Restores file permissions only.
• attribs.sh → Restores both permissions and ownership.
  • Run with no arguments → restores both.
  • Run with -o → ownership only.
  • Run with -p → permissions only.
• [symlinks.sh](#bonus-handling-symlinks

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tar -a -c -f archive.tar.gz folder
tar -a -c -farchive.tar.gz folder
tar -a -cf archive.tar.gz folder
tar -a -cfarchive.tar.gz folder
tar -ac -f archive.tar.gz folder
tar -ac -farchive.tar.gz folder
tar -acf archive.tar.gz folder
tar -acfarchive.tar.gz folder
tar a -c -f archive.tar.gz folder
tar a -c -farchive.tar.gz folder

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Norwegian Macbook Keyboard Tweaks (Ubuntu 24.04/25.10)

This patch modifies the Norwegian Macintosh keyboard layout on Ubuntu Linux to better match that of a modern Macbook's physical labels and expectations:

• Replaces | (pipe) with ' (apostrophe) as the primary symbol for the key below esc
• Promotes $ to Shift+4
• Introduces € as AltGr+4
• Demotes ¤ (currency) to Shift+AltGr+4 (since this is hardly used these days)
• Swaps the order of the dead keys of the ´ (acute) and ​`​ (grave) acents on the key to left of backspace ←
• Enables access to higher level symbols by setting the right-most Alt ⌥ (Option) key as AltGr