Boot folder

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In Unix-like operating systems, a boot folder is the directory which holds files used in booting the operating system, typically {{Mono|/boot}}. The usage is standardized within Linux in the Filesystem Hierarchy Standard.{{cite web |url=https://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch03s05.html |title=3.5. /boot : Static files of the boot loader |date=March 19, 2015 |website=Linux Foundation Referenced Specifications |access-date=June 7, 2021}}

The contents are mostly Linux kernel files or boot loader files, depending on the boot loader, most commonly (on Linux) LILO or GRUB.

=Linux=

vmlinux – the Linux kernel{{cite book

| last = Ward

| first = Brian

| title = How Linux works what every superuser should know

| publisher = No Starch Press

| location = San Francisco

| year = 2004

| isbn = 1593270356

| page = 219}}

initrd.img – a temporary file system, used prior to loading the kernel{{cite book

| last = Lombardo

| first = John

| title = Embedded Linux

| publisher = New Riders

| location = Indianapolis, Ind

| year = 2001

| isbn = 9780735709980

| page = 17}}

System.map – a symbol lookup table{{cite book

| last = Kopper

| first = Karl

| title = The Linux Enterprise Cluster build a highly available cluster with commodity hardware and free software

| publisher = No Starch Press

| location = San Francisco

| year = 2008

| isbn = 978-1593270360

| page = 61}}

=LILO=

LILO creates and uses the following files:

map – a key file, which records where files needed by LILO during boot are stored. Following kernel upgrades, this file must be regenerated by running the "map installer", which is {{mono|/sbin/lilo}} otherwise the system will not boot.
boot.xxyy – these 512-byte files are backups of boot sectors, either the master boot record (MBR) or volume boot record (VBR), created when LILO overwrites a boot sector. xx and yy are the major and minor device numbers in hex;{{Cite web |title=LILO mini-HOWTO: Background Information and Standard Installation |url=https://tldp.org/HOWTO/LILO-2.html#ss2.4 |access-date=2022-11-26 |website=tldp.org}} for example, the drive {{mono|sda}} has numbers 8, 0, hence its MBR is backed up to {{mono|boot.0800}} while the partition {{mono|sda3}} has numbers 8,3, hence its VBR is backed up to {{mono|boot.0803}}.

LILO may also use other files, such as {{mono|message}} and also stores a non-boot configuration file in {{mono|/etc/lilo.conf}}.

=GRUB=

GRUB stores its files in the subdirectory {{mono|grub/}} (i.e. {{mono|/boot/grub/}}). These files are mostly modules ({{mono|.mod}}), with configuration stored in {{mono|grub.cfg}}.

Location

{{mono|/boot/}} is often simply a directory on the main (or only) hard drive partition. However, it may be a separate partition. A separate partition is generally only used when bootloaders are incapable of reading the main filesystem (e.g. LILO does not recognize XFS) or other problems not easily resolvable by users.{{Citation needed|date=February 2024}}

On UEFI systems, including most modern PCs, the EFI system partition is often mounted at {{mono|/boot/}}, {{mono|/efi/}} or {{mono|/boot/efi/}}.{{Cite web |title=EFI System Partition - Gentoo wiki |url=https://wiki.gentoo.org/wiki/EFI_System_Partition#Mount_point |access-date=2024-02-15 |website=wiki.gentoo.org}}{{Cite web |title=EFI system partition - ArchWiki |url=https://wiki.archlinux.org/title/EFI_system_partition#Mount_the_partition |access-date=2024-02-15 |website=wiki.archlinux.org}}

References

Category:Linux kernel

Category:Unix file system technology

Category:System administration

Category:File system directories