# EXTLINUX ## Identification `$PATH` locates executable commands; `$XDG_CONFIG_HOME` locates per-user configuration under the XDG standard. `.netrc` can contain login credentials for network clients and must be permission-protected. `isohybrid` makes some ISO images bootable from optical or disk-like media. [[EXTLINUX|EXTLINUX]] is part of SYSLINUX; [[AUFS|AUFS]] is a union filesystem used by some live systems. ## Notebook evidence - [[Scanned_20260730-1719#PDF page 68 — Environment variables, ISO hybrid boot, GRUB, extlinux, and AUFS|PDF page 68: Environment variables, ISO hybrid boot, GRUB, extlinux, and AUFS]] — This is the configuration anatomy of a portable live system: command discovery, user config, automated network access, hybrid media, boot loader, and a writable overlay atop read-only content. ## Relationships and overlays The source places this note in a shared evidence cluster with [[AUFS|AUFS]]. Within the larger collection, this evidence extends [[Vendor-Agnostic Recovery|vendor-agnostic recovery]] and [[Continuity Architecture|continuity architecture]] by showing how software, hardware, identity, and pre-OS control depend on recoverable interfaces. ## Evidentiary status and open leads Add `.netrc` permission requirements, secret handling, overlay persistence limits, and BIOS-versus-UEFI boot tests. ## Source - [[Scanned_20260730-1719|Scanned_20260730-1719]]