https://wiki.archlinux.org/api.php?action=feedcontributions&user=Ivan+p&feedformat=atomArchWiki - User contributions [en]2024-03-29T09:18:30ZUser contributionsMediaWiki 1.41.0https://wiki.archlinux.org/index.php?title=MariaDB&diff=391244MariaDB2015-08-15T15:48:21Z<p>Ivan p: /* Grant remote access */ Replaced red link with category link</p>
<hr />
<div>[[Category:Database management systems]]<br />
[[cs:MySQL]]<br />
[[de:MySQL]]<br />
[[es:MySQL]]<br />
[[fr:MariaDB]]<br />
[[it:MySQL]]<br />
[[ja:MySQL]]<br />
[[ru:MySQL]]<br />
[[sr:MySQL]]<br />
[[tr:MySQL]]<br />
[[zh-CN:MySQL]]<br />
{{Related articles start}}<br />
{{Related|phpMyAdmin}}<br />
{{Related|Adminer}}<br />
{{Related articles end}}<br />
MySQL is a widely spread, multi-threaded, multi-user SQL database. For more information about features, see the [http://www.mysql.com/ official homepage].<br />
<br />
{{Note|MariaDB is now officially Arch Linux's default implementation of MySQL. It is recommended for all users to [[#Upgrade from Oracle MySQL to MariaDB|upgrade]] to MariaDB. Oracle MySQL was dropped to the [[AUR]]. See [https://www.archlinux.org/news/mariadb-replaces-mysql-in-repositories/ the announcement].}}<br />
<br />
== Installation ==<br />
<br />
[https://mariadb.org/ MariaDB] is the [https://www.archlinux.org/news/mariadb-replaces-mysql-in-repositories/ default implementation] of MySQL in Arch Linux, provided with the {{Pkg|mariadb}} package.<br />
<br />
Alternative implementations are:<br />
* {{App|Oracle MySQL|An implementation by Oracle Corporation.|https://www.mysql.com/|{{AUR|mysql}}}}<br />
* {{App|Percona Server|An implementation by Percona LLC.|http://www.percona.com/software/percona-server/|{{Pkg|percona-server}}}}<br />
<br />
{{Tip|<br />
* If the database (in {{ic|/var/lib/mysql}}) resides on a [[Btrfs]] file system, you should consider disabling [[Btrfs#Copy-On-Write_.28CoW.29|Copy-on-Write]] for the directory before creating any database.<br />
* If the database resides on a [[ZFS]] file system, you should consult [[ZFS#Database]] before creating any database.<br />
}}<br />
<br />
Install {{Pkg|mariadb}}, afterwards run the following command '''before starting''' the {{ic|mysqld.service}}:<br />
# mysql_install_db --user=mysql --basedir=/usr --datadir=/var/lib/mysql<br />
Now the {{ic|mysqld.service}} can be started and/or enabled with [[systemd#Using units|systemd]].<br />
<br />
It is recommended to secure the MySQL installation by running the following command:<br />
# mysql_secure_installation<br />
<br />
To simplify administration, you might want to install a front-end such as {{Pkg|mysql-workbench}} and/or [[Adminer]].<br />
<br />
===Upgrade MariaDB===<br />
You might consider running running the following command after a (major) version upgrade (such as from 5.5 to 10.0, or from 10.0 to 10.1):<br />
# mysql_upgrade -u root -p<br />
<br />
=== Upgrade from Oracle MySQL to MariaDB ===<br />
{{Note|It could be necessary to remove the following files from {{ic|/var/lib/mysql}} : {{ic|ib_logfile0}}, {{ic|ib_logfile1}} and {{ic|aria_log_control}}, before restarting the daemon in the following procedure.}}<br />
<br />
See [https://www.archlinux.org/news/mariadb-replaces-mysql-in-repositories/ the announcement] for the procedure to follow.<br />
<br />
== Configuration ==<br />
Once you have started the MySQL server and added a root account, you may want to change the default configuration.<br />
<br />
To log in as {{ic|root}} on the MySQL server, use the following command:<br />
$ mysql -u root -p<br />
<br />
=== Add user ===<br />
Creating a new user takes two steps: create the user; grant privileges. In the below example, the user ''monty'' with ''some_pass'' as password is being created: <br />
<br />
{{hc|$ mysql -u root -p|<br />
MariaDB> CREATE USER 'monty'@'localhost' IDENTIFIED BY 'some_pass';<br />
MariaDB> GRANT ALL PRIVILEGES ON *.* TO 'monty'@'localhost'<br />
-> WITH GRANT OPTION;<br />
MariaDB> quit}}<br />
<br />
=== Configuration files ===<br />
<br />
''MariaDB'' configuration options are read from the following files in the given order (according to {{ic|mysqld --help --verbose | tail -20}} output):<br />
/etc/my.cnf /etc/mysql/my.cnf ~/.my.cnf<br />
<br />
Depending on the scope of the changes you want to make (system-wide, user-only...), use the corresponding file. See [https://mariadb.com/kb/en/mariadb/documentation/getting-started/starting-and-stopping-mariadb/mysqld-configuration-files-and-groups/ this entry] of the KnowledgeBase for more information.<br />
<br />
=== Grant remote access ===<br />
{{Warning|This is not considered as best practice and may cause security issues. Consider using [[Secure Shell]], [[VNC]] or [[:Category:Virtual Private Network|VPN]], if you want to maintain the MySQL-server outside and/or inside your LAN.}}<br />
If you want to access your MySQL server from other LAN hosts, you have to edit the following lines in {{ic|/etc/mysql/my.cnf}}:<br />
[mysqld]<br />
...<br />
#skip-networking<br />
bind-address = <some ip-address><br />
...<br />
<br />
Grant any MySQL user remote access (example for root):<br />
$ mysql -u root -p<br />
Check current users with remote access privileged:<br />
SELECT User, Host FROM mysql.user WHERE Host <> 'localhost';<br />
Now grant remote access for your user (here root)::<br />
GRANT ALL PRIVILEGES ON *.* TO 'root'@'192.168.1.%' IDENTIFIED BY 'my_optional_remote_password' WITH GRANT OPTION;<br />
You can change the '%' wildcard to a specific host if you like. The password can be different from user's main password.<br />
<br />
=== Disable remote access ===<br />
The MySQL server is accessible from the network by default. If MySQL is only needed for the localhost, you can improve security by not listening on TCP port 3306. To refuse remote connections, uncomment the following line in {{ic|/etc/mysql/my.cnf}}:<br />
skip-networking<br />
<br />
You will still be able to log in from the localhost.<br />
<br />
=== Enable auto-completion ===<br />
{{Note|Enabling this feature can make the client initialization longer.}}<br />
The MySQL client completion feature is disabled by default. To enable it system-wide edit {{ic|/etc/mysql/my.cnf}}, and replace {{ic|no-auto-rehash}} by {{ic|auto-rehash}}. Completion will be enabled next time you run the MySQL client.<br />
<br />
=== Using UTF-8 ===<br />
In the {{ic|/etc/mysql/my.cnf}} file section under the {{ic|mysqld}} group, add:<br />
<br />
{{bc|<nowiki><br />
[mysqld]<br />
init_connect = 'SET collation_connection = utf8_general_ci,NAMES utf8'<br />
collation_server = utf8_general_ci<br />
character_set_client = utf8<br />
character_set_server = utf8<br />
</nowiki>}}<br />
<br />
=== Using a TMPFS for tmpdir ===<br />
The directory used by MySQL for storing temporary files is named ''tmpdir''. For example, it is used to perform disk based large sorts, as well as for internal and explicit temporary tables.<br />
<br />
Create the directory with appropriate permissions:<br />
# mkdir -pv /var/lib/mysqltmp<br />
# chown mysql:mysql /var/lib/mysqltmp<br />
<br />
Find the id and gid of the {{ic|mysql}} user and group:<br />
$ id mysql<br />
uid=27(mysql) gid=27(mysql) groups=27(mysql)<br />
<br />
Add to your {{ic|/etc/fstab}} file.<br />
tmpfs /var/lib/mysqltmp tmpfs rw,gid=27,uid=27,size=100M,mode=0750,noatime 0 0<br />
<br />
Add to your {{ic|/etc/mysql/my.cnf}} file under the {{ic|mysqld}} group:<br />
tmpdir = /var/lib/mysqltmp<br />
<br />
Then reboot or ( shutdown mysql, mount the tmpdir, start mysql ).<br />
<br />
=== Time zone tables ===<br />
Although time zone tables are created during the installation, they are not automatically populated. They need to be populated if you are planning on using CONVERT_TZ() in SQL queries.<br />
<br />
To populate the time zone tables with all the time zones:<br />
$ mysql_tzinfo_to_sql /usr/share/zoneinfo | mysql -u root -p mysql<br />
<br />
Optionally, you may populate the table with specific time zone files:<br />
$ mysql_tzinfo_to_sql <timezone_file> <timezone_name> | mysql -u root -p mysql<br />
<br />
== Backup ==<br />
<br />
There are various [https://mariadb.com/kb/en/mariadb/documentation/backing-up-and-restoring/ tools and strategies] to back up your databases.<br />
<br />
If you are using the default InnoDB storage engine, a [https://mariadb.com/kb/en/mariadb/documentation/clients-and-utilities/backup-restore-and-import/mysqldump/#examples suggested] way of backing up all your bases online while provisioning for [https://dev.mysql.com/doc/refman/5.6/en/password-security-user.html point-in-time recovery] (also known as “roll-forward,” when you need to restore an old backup and replay the changes that happened since that backup) is to execute the following command:<br />
<br />
$ mysqldump --single-transaction --flush-logs --master-data=2 --all-databases -u root -p > all_databases.sql<br />
<br />
This will prompt for '''MariaDB's''' root user's password, which was defined during database [[#Configuration]].<br />
<br />
Specifying the password on the command line is [https://dev.mysql.com/doc/refman/5.6/en/password-security-user.html strongly discouraged], as it exposes it to discovery by other users through the use of {{ic|ps aux}} or other techniques. Instead, the aforementioned command will prompt for the specified user's password, concealing it away.<br />
<br />
=== Compression ===<br />
As SQL tables can get pretty large, it is recommended to pipe the output of the aforementioned command in a compression utility like {{Pkg|gzip}}:<br />
$ mysqldump --single-transaction --flush-logs --master-data=2 --all-databases -u root -p | gzip > all_databases.sql.gz<br />
<br />
Decompressing the backup thus created and reloading it in the server is achieved by doing:<br />
$ gunzip all_databases.sql.gz | mysql -u root -p<br />
<br />
This will recreate and repopulate all the databases previously backed up (see [https://stackoverflow.com/questions/23180963/restore-all-mysql-database-from-a-all-database-sql-gz-file#comment35453351_23180977 this] or [http://www.linuxquestions.org/questions/linux-server-73/how-to-restore-mysqldump-all-databases-backup-892922/ this]).<br />
<br />
=== Non-interactive ===<br />
<br />
If you want to setup non-interactive backup script for use in [[cron]] jobs or [[Systemd/cron_functionality|systemd timers]], see [https://dev.mysql.com/doc/refman/5.6/en/option-files.html option files] and [https://stackoverflow.com/a/9293090 this illustration] for ''mysqldump''.<br />
<br />
Basically you should add the following section to the relevant [[#Configuration_files|configuration file]]:<br />
{{bc|<nowiki><br />
[mysqldump]<br />
user=mysqluser<br />
password=secret<br />
</nowiki>}}<br />
<br />
Mentioning a user here is optional, but doing so will free you from having to mention it on the command line.<br />
<br />
==== Example script ====<br />
<br />
The database can be dumped to a file for easy backup. The following shell script will do this for you, creating a {{ic|db_backup.gz}} file in the same directory as the script, containing your database dump:<br />
<br />
{{bc|<nowiki><br />
#!/bin/bash<br />
<br />
THISDIR=$(dirname $(readlink -f "$0"))<br />
<br />
mysqldump --single-transaction --flush-logs --master-data=2 --all-databases \<br />
| gzip > $THISDIR/db_backup.gz<br />
echo 'purge master logs before date_sub(now(), interval 7 day);' | mysql<br />
</nowiki>}}<br />
<br />
See also the official {{ic|mysqldump}} page in the [http://dev.mysql.com/doc/refman/5.6/en/mysqldump.html MySQL] and [https://mariadb.com/kb/en/mariadb/documentation/clients-and-utilities/backup-restore-and-import/mysqldump MariaDB] manuals.<br />
<br />
=== Holland Backup ===<br />
<br />
A python-based software package named [http://hollandbackup.org/ Holland Backup] is available in [[AUR]] to automate all of the backup work. It supports direct mysqldump, LVM snapshots to tar files (mysqllvm), LVM snapshots with mysqldump (mysqldump-lvm), and {{pkg|xtrabackup}} methods to extract the data. The Holland framework supports a multitude of options and is highly configurable to address almost any backup situation.<br />
<br />
The main {{AUR|holland}} and {{AUR|holland-common}} packages provide the core framework; one of the sub-packages ({{AUR|holland-mysqldump}}, {{AUR|holland-mysqllvm}} and/or {{AUR|holland-xtrabackup}} must be installed for full operation. Example configurations for each method are in the {{ic|/usr/share/doc/holland/examples/}} directory and can be copied to {{ic|/etc/holland/backupsets/}}, as well as using the {{ic|holland mk-config}} command to generate a base config for a named provider.<br />
<br />
== Troubleshooting ==<br />
=== MySQL daemon cannot start ===<br />
If MySQL fails to start and there is no entry in the log files, you might want to check the permissions of files in the directories {{ic|/var/lib/mysql}} and {{ic|/var/lib/mysql/mysql}}. If the owner of files in these directories is not {{ic|mysql:mysql}}, you should do the following:<br />
# chown mysql:mysql /var/lib/mysql -R<br />
If you run into permission problems despite having followed the above, ensure that your {{ic|my.cnf}} is copied to {{ic|/etc/}}:<br />
# cp /etc/mysql/my.cnf /etc/my.cnf<br />
Now try and start the daemon.<br />
<br />
If you get these messages in your {{ic|/var/lib/mysql/hostname.err}}:<br />
[ERROR] Can't start server : Bind on unix socket: Permission denied<br />
[ERROR] Do you already have another mysqld server running on socket: /var/run/mysqld/mysqld.sock ?<br />
[ERROR] Aborting<br />
the permissions of {{ic|/var/run/mysqld}} could be the culprit.<br />
# chown mysql:mysql /var/run/mysqld -R<br />
<br />
If you run mysqld and the following error appears:<br />
Fatal error: Can’t open and lock privilege tables: Table ‘mysql.host’ doesn’t exist<br />
Run the following command from the {{ic|/usr}} directory to install the default tables:<br />
# cd /usr<br />
# mysql_install_db --user=mysql --ldata=/var/lib/mysql/<br />
<br />
=== Unable to run mysql_upgrade because MySQL cannot start ===<br />
Try run MySQL in safemode:<br />
# mysqld_safe --datadir=/var/lib/mysql/<br />
And then run:<br />
# mysql_upgrade -u root -p<br />
<br />
=== Reset the root password ===<br />
Stop {{ic|mysqld.service}}. Issue the following command:<br />
# mysqld_safe --skip-grant-tables &<br />
Connect to the mysql server. Issue the following command:<br />
# mysql -u root mysql<br />
Change root password:<br />
mysq/> use mysql;<br />
mysql> UPDATE mysql.user SET Password=PASSWORD('MyNewPass') WHERE User='root';<br />
mysql> FLUSH PRIVILEGES;<br />
mysql> exit<br />
Start {{ic|mysqld.service}}.<br />
<br />
=== Check and repair all tables ===<br />
Check and auto repair all tables in all databases, [http://dev.mysql.com/doc/refman/5.7/en/mysqlcheck.html see more]:<br />
# mysqlcheck -A --auto-repair -u root -p<br />
<br />
=== Optimize all tables ===<br />
Forcefully optimize all tables, automatically fixing table errors that may come up.<br />
# mysqlcheck -A --auto-repair -f -o -u root -p<br />
<br />
=== OS error 22 when running on ZFS ===<br />
If you are using [[ZFS]] and get the following error:<br />
InnoDB: Operating system error number 22 in a file operation.<br />
You need to disable aio_writes by adding a line to the mysqld-section in /etc/mysql/my.cnf <br />
[mysqld]<br />
...<br />
innodb_use_native_aio = 0<br />
<br />
However, if the post install scripts failed because of the above issue, MySQL/MariaDB might be in an invalid state. To recover from this state, execute the following:<br />
rm -rf /var/lib/mysql/*<br />
mysql_install_db --user=mysql --basedir=/usr --datadir=/var/lib/mysql<br />
chown -R mysql:mysql /var/lib/mysql &>/dev/null<br />
/usr/bin/systemd-tmpfiles --create mysql.conf<br />
<br />
After which MySQL/MariaDB should be installed correctly.<br />
<br />
=== Cannot login through CLI, but phpmyadmin works well ===<br />
This may happen if you are using a long (>70-75) password.<br />
As for 5.5.36, for some reason, mysql CLI cannot handle that much characters in readline mode.<br />
So, if you are planning to use the recommended password input mode:<br />
$ mysql -u <user> -p<br />
Password:<br />
consider changing the password to smaller one.<br />
<br />
{{Note|You still can log in by specifying the password as an argument to mysql command.<br />
{{Warning|This behavior is considered dangerous, because your password might leak, for example, to the logs. Use it only in case of emergency and do not forget to change password right afterwards.}}<br />
$ mysql -u <user> -p"<some-veryveryveryveryveryveryveryveryveryveryveryveryveryveryvery-long-and-veryveryveryveryveryveryveryveryveryvery-strong-password>"<br />
}}<br />
<br />
===MySQL binary logs are taking up huge disk space===<br />
By default, mysqld creates binary log files in {{ic|/var/lib/mysql}}. This is useful for replication master server or data recovery. But these binary logs can eat up your disk space. If you do not plan to use replication or data recovery features, you may disable binary logging by commenting out these lines in {{ic|/etc/mysql/my.cnf}}:<br />
#log-bin=mysql-bin<br />
#binlog_format=mixed<br />
Alternatively, you can purge some binary logs in {{ic|/var/lib/mysql}} to free up disk space with this command:<br />
#mysql -u root -p"PASSWORD" -e "PURGE BINARY LOGS TO 'mysql-bin.0000xx';"<br />
<br />
== See also ==<br />
<br />
* [https://mariadb.org/ MariaDB Official Website]<br />
* [https://mariadb.com/kb/en/ MariaDB knowledge Base]<br />
* [http://dev.mysql.com/doc/ MySQL documentation ]<br />
* [[LAMP]] - ArchWiki article covering the setup of a LAMP server (Linux Apache MySQL PHP)<br />
* [[PhpMyAdmin]] - ArchWiki article covering the web-based tool to help manage MySQL databases using an Apache/PHP front-end.<br />
* [[PHP]] - ArchWiki article on PHP.<br />
* [http://www.askapache.com/mysql/performance-tuning-mysql.html MySQL Performance Tuning Scripts and Know-How]</div>Ivan phttps://wiki.archlinux.org/index.php?title=GRUB&diff=213838GRUB2012-07-21T10:22:25Z<p>Ivan p: /* Preface */ cleaned up lines' ends.</p>
<hr />
<div>[[Category:Boot loaders]]<br />
[[cs:GRUB2]]<br />
[[es:GRUB2]]<br />
[[fr:GRUB2]]<br />
[[id:GRUB2]]<br />
[[it:GRUB2]]<br />
[[ru:GRUB2]]<br />
[[tr:GRUB2]]<br />
[[zh-CN:GRUB2]]<br />
[[zh-TW:GRUB2]]<br />
{{Article summary start}}<br />
{{Article summary text|Covers various aspects of the next generation of the GRand Unified Bootloader (GRUB2).}}<br />
{{Article summary heading|Overview}}<br />
{{Article summary text|{{Boot process overview}}}}<br />
{{Article summary heading|Related}}<br />
{{Article summary wiki|Burg}} - Burg is a brand-new boot loader based on GRUB2. It uses a new object format which allows it to be built in a wider range of OS, including Linux, Windows, OS X, Solaris, FreeBSD, etc. It also has a highly configurable menu system which works in both text and graphic mode. <br />
{{Article summary heading|Resources}}<br />
{{Article summary link|GNU GRUB -- GNU Project|https://www.gnu.org/software/grub/}}<br />
{{Article summary end}}<br />
<br />
[https://www.gnu.org/software/grub/ GRUB2] is the next generation of the GRand Unified Bootloader (GRUB). GRUB2 is derived from [http://www.nongnu.org/pupa/ PUPA] which was a research project to investigate the next generation of GRUB. GRUB2 has been rewritten from scratch to clean up everything and provide modularity and portability [https://www.gnu.org/software/grub/grub-faq.en.html#q1].<br />
<br />
In brief, the ''bootloader'' is the first software program that runs when a computer starts. It is responsible for loading and transferring control to the Linux kernel. The kernel, in turn, initializes the rest of the operating system.<br />
<br />
== Preface ==<br />
Here is some information needs to be clarified:<br />
* The name ''GRUB'' officially refers to version ''2'' of the software, see [https://www.gnu.org/software/grub/]. If you are looking for the article on the legacy version, see [[GRUB Legacy]].<br />
<br />
* [[GRUB Legacy]] (i.e. version 0.9x) is considered legacy by upstream and is being replaced by GRUB2 and [[Syslinux]] in Arch Linux. See the news [https://www.archlinux.org/news/grub-legacy-no-longer-supported/ here]. Upstream recommends GRUB2 >=1.99 over GRUB Legacy, even for current GRUB Legacy users.<br />
<br />
* The [[Archboot]] ISO's installer script supports {{Pkg|grub-bios}} and {{Pkg|grub-efi-x86_64}} installation. The official installer script AIF (Arch Installation Framework) does not support GRUB(2) yet.<br />
<br />
* From 1.99-6 onwards, GRUB2 supports [[Btrfs]] as root (without a separate {{ic|/boot}} filesystem) compressed with either zlib or LZO.<br />
<br />
* For GRUB2 UEFI info, it is recommended to read the [[UEFI]], [[GPT]] and [[UEFI_Bootloaders]] pages before reading this page.<br />
<br />
=== Notes for current GRUB Legacy users ===<br />
* Although GRUB legacy will not be removed from your system and will stay fully functional, you should consider upgrading to GRUB version 2.x, or one of the other supported bootloaders.<br />
<br />
* Upgrade from [[GRUB Legacy]] to [[GRUB]](2) is the much same as installing GRUB from a running Arch Linux which is covered [[#From a running Arch Linux|below]].<br />
<br />
* There are differences in the commands of GRUB and GRUB2. Familiarize yourself with [https://www.gnu.org/software/grub/manual/grub.html#Commands GRUB2 commands] before proceeding (e.g. "find" has been replaced with "search").<br />
<br />
* GRUB2 is now ''modular'' and no longer requires "stage 1.5". As a result, the bootloader itself is limited -- modules are loaded from the hard drive as needed to expand functionality (e.g. for [[LVM]] or RAID support).<br />
<br />
* Device naming has changed between GRUB and GRUB2. Partitions are numbered from 1 instead of 0 while drives are still numbered from 0, and prefixed with partition-table type. For example, {{ic|/dev/sda1}} would be referred to as {{ic|(hd0,msdos1)}} (for MBR) or {{ic|(hd0,gpt1)}} (for GPT) using GRUB2.<br />
<br />
=== Preliminary Requirements for GRUB2 ===<br />
<br />
==== BIOS systems ====<br />
<br />
===== [[GPT]] specific instructions =====<br />
<br />
GRUB2 in BIOS-GPT configuration requires a BIOS Boot Partition to embed its {{ic|core.img}} in the absence of post-MBR gap in GPT partitioned systems (which is taken over by the GPT Primary Header and Primary Partition table). This partition is used by GRUB2 only in BIOS-GPT setups. No such partition type exists in case of MBR partitioning (at least not for GRUB2). This partition is also not required if the system is UEFI based, as no embedding of bootsectors takes place in that case. Syslinux does not require this partition.<br />
<br />
For a BIOS-GPT configuration, create a 2 MiB partition using cgdisk or GNU Parted with no filesystem. The location of the partition in the partition table does not matter but it should be within the first 2 TiB region of the disk. It is advisable to put it somewhere in the beginning of the disk before the {{ic|/boot}} partition. Set the partition type to "EF02" in cgdisk or {{ic|set <BOOT_PART_NUM> bios_grub on}} in GNU Parted.<br />
<br />
{{Note|This partition should be created before {{ic|grub-install}} or {{ic|grub-setup}} is run or before the '''Install Bootloader''' step of the Archlinux installer (if GRUB2 BIOS is selected as bootloader).}}<br />
<br />
===== [[MBR]] aka msdos partitioning specific instructions =====<br />
<br />
Usually the post-MBR gap (after the 512 byte MBR region and before the start of the 1st partition) in many MBR (or msdos disklabel) partitioned systems is 32 KiB when DOS compatibility cylinder alignment issues are satisfied in the partition table. However a post-MBR gap of about 1 to 2 MiB is recommended to provide sufficient room for embedding GRUB2's {{ic|core.img}} ({{bug|24103}}). It is advisable to use a partitioner which supports 1 MiB partition alignment to obtain this space as well as satisfy other non-512 byte sector issues (which are unrelated to embedding of {{ic|core.img}}).<br />
<br />
If you do not dual-boot with MS Windows (any version) in BIOS systems, it is advisable to switch to GPT partitioning - [[GUID_Partition_Table#Convert_from_MBR_to_GPT]]<br />
<br />
{{Note|Create the 2MiB partition mentioned above BEFORE you convert to GPT. If you do not, gparted will not resize your boot partition to allow its creation, and when you reboot GRUB2 will not know where to look.}}<br />
<br />
==== UEFI systems ====<br />
<br />
===== Create and Mount the UEFI SYSTEM PARTITION =====<br />
<br />
{{Note|It is recommended to read the [[UEFI]], [[GPT]] and [[UEFI_Bootloaders]] pages before reading this part.}}<br />
<br />
Follow [[Unified_Extensible_Firmware_Interface#Create_an_UEFI_System_Partition_in_Linux]] for instructions on creating a UEFI SYSTEM PARTITION. Then mount the UEFI SYSTEM PARTITION at {{ic|/boot/efi}}. If you have mounted the UEFISYS partition in some other mountpoint, replace {{ic|/boot/efi}} in the below instructions with that mountpoint:<br />
<br />
# mkdir -p /boot/efi<br />
# mount -t vfat <UEFISYS_PART_DEVICE> /boot/efi<br />
<br />
Create a <UEFI_SYSTEM_PARTITION>{{ic|/EFI}} directory, if it does not exist:<br />
<br />
# mkdir -p /boot/efi/EFI<br />
<br />
== Installation ==<br />
<br />
=== During Arch Linux installation ===<br />
<br />
* Skip the '''Install Bootloader''' step and exit the installer.<br />
* Configure the network:<br />
# aif -p partial-configure-network<br />
This will bring up a prompt; put in the network interface to use, (e.g., {{ic|eth0}}) and use DHCP for easy configuration.<br />
* If you did not configure the installed system's {{ic|/etc/resolv.conf}} file during installation (for instance, if you plan to let DHCP generate it later), you will need to copy the one generated by AIF when it configured the network:<br />
# cp /etc/resolv.conf /mnt/etc/resolv.conf<br />
* If you run into network issues in the pacman update step below, you may have needed to install the {{Pkg|net-tools}} package.<br />
* Check and see if the {{ic|dm_mod}} module is loaded. If it is not, load it manually:<br />
# lsmod | grep dm_mod<br />
# modprobe dm-mod<br />
{{Note|This is necessary at this point, and cannot be postponed after the chroot. If you try to use modprobe in a chroot environment that has a later kernel version from that of the installing device (at the time of writing, 2.6.33), modprobe will fail. This happens routinely using the Arch "net" installations.}}<br />
* From the installer's live shell, chroot to the installed system:<br />
# mount -o bind /dev /mnt/dev<br />
# mount -t proc /proc /mnt/proc/<br />
# mount -t sysfs /sys /mnt/sys/<br />
# chroot /mnt bash<br />
* Refresh the package list (with an extra {{ic|-y}} flag to force a refresh of all package lists even if they appear to be up to date):<br />
# pacman -Syy<br />
* Install the GRUB2 package as mentioned in the section [[#From a running Arch Linux]] (Note that the {{ic|dm-mod}} module has already been loaded, no need to do that again).<br />
<br />
=== From a running Arch Linux ===<br />
<br />
==== BIOS systems ====<br />
<br />
===== Backup Important Data =====<br />
<br />
Although a GRUB(2) installation should run smoothly, it is strongly recommended to keep the GRUB Legacy files before installing {{Pkg|grub-bios}}.<br />
<br />
# mv /boot/grub /boot/grub-legacy<br />
<br />
Backup the MBR which contains the boot code and partition table (Replace {{ic|/dev/sd'''X'''}} with your actual disk path)<br />
<br />
# dd if=/dev/sdX of=/path/to/backup/mbr_backup bs=512 count=1<br />
<br />
Only 446 bytes of the MBR contain boot code, the next 64 contain the partition table. If you do not want to overwrite your partition table when restoring, it is strongly advised to backup only the MBR boot code:<br />
<br />
# dd if=/dev/sdX of=/path/to/backup/bootcode_backup bs=446 count=1<br />
<br />
If unable to install GRUB2 correctly, see [[GRUB2#Restore_GRUB_Legacy]].<br />
<br />
===== Install grub-bios package =====<br />
<br />
The GRUB(2) packages can be installed with pacman (and will replace {{Pkg|grub-legacy}} or {{Pkg|grub}}, if it is installed):<br />
<br />
# pacman -S grub-bios<br />
<br />
{{Note|Simply installing the package won't update the {{ic|/boot/grub/i386-pc/core.img}} file and the GRUB(2) modules in {{ic|/boot/grub/i386-pc}}. You need to update them manually using {{ic|grub-install}} as explained below.}}<br />
<br />
Also load the device-mapper kernel module without which {{ic|grub-probe}} does not reliably detect disks and partitions:<br />
<br />
# modprobe dm_mod<br />
<br />
===== Install grub-bios boot files =====<br />
<br />
There are 3 ways to install GRUB(2) boot files in BIOS booting:<br />
*[[#Install_to_440-byte_MBR_boot_code_region]] (recommended) , <br />
*[[#Install_to_Partition_or_Partitionless_Disk]] (not recommended),<br />
*[[#Generate_core.img_alone]] (safest method, but requires another BIOS bootloader like [[grub-legacy]] or [[syslinux]] to be installed to chainload {{ic|/boot/grub/i386-pc/core.img}}). <br />
<br />
====== Install to 440-byte MBR boot code region ======<br />
<br />
To setup {{ic|grub-bios}} in the 440-byte Master Boot Record boot code region, populate the {{ic|/boot/grub}} directory, generate the {{ic|/boot/grub/i386-pc/core.img}} file, and embed it in the 32 KiB (minimum size - varies depending on partition alignment) post-MBR gap (MBR disks) or in BIOS Boot Partition (GPT disks), run:<br />
<br />
# grub-install --directory=/usr/lib/grub/i386-pc --target=i386-pc --boot-directory=/boot --recheck --debug /dev/sda<br />
# mkdir -p /boot/grub/locale<br />
# cp /usr/share/locale/en\@quot/LC_MESSAGES/grub.mo /boot/grub/locale/en.mo<br />
<br />
where {{ic|/dev/sda}} is the destination of the installation (in this case the MBR of the first SATA disk). If you use [[LVM]] for your {{ic|/boot}}, you can install GRUB2 on multiple physical disks. <br />
<br />
The {{ic|--no-floppy}} tells {{ic|grub-bios}} utilities not to search for any floppy devices which reduces the overall execution time of {{ic|grub-install}} on many systems (it will also prevent the issue below from occurring). Otherwise you get an error that looks like this:<br />
<br />
grub-probe: error: Cannot get the real path of '/dev/fd0'<br />
Auto-detection of a filesystem module failed.<br />
Please specify the module with the option '--modules' explicitly.<br />
<br />
{{Note|{{ic|--no-floppy}} has been removed from {{ic|grub-install}} in 2.00~beta2 upstream release, and replaced with {{ic|--allow-floppy}}.}}<br />
<br />
{{Warning|Make sure to check the {{ic|/boot}} directory if you use the latter. Sometimes the {{ic| boot-directory}} parameter creates another {{ic|/boot}} folder inside of {{ic|/boot}}. A wrong install would look like: {{ic|/boot/boot/grub/}}.}}<br />
<br />
====== Install to Partition or Partitionless Disk ======<br />
<br />
{{Note|{{ic|grub-bios}} (any version - including upstream Bazaar repo) does not encourage installation to a partition boot sector or a partitionless disk like GRUB Legacy or syslinux does. This kind of setup is prone to breakage, especially during updates, and is not supported by Arch devs.}}<br />
<br />
To set up {{ic|grub-bios}} to a partition boot sector, to a partitionless disk (also called superfloppy) or to a floppy disk, run (using for example {{ic|/dev/sdaX}} as the {{ic|/boot}} partition):<br />
<br />
# chattr -i /boot/grub/i386-pc/core.img<br />
# grub-install --directory=/usr/lib/grub/i386-pc --target=i386-pc --boot-directory=/boot --recheck --force --debug /dev/sdaX<br />
# mkdir -p /boot/grub/locale<br />
# cp /usr/share/locale/en@quot/LC_MESSAGES/grub.mo /boot/grub/locale/en.mo<br />
# chattr +i /boot/grub/i386-pc/core.img<br />
<br />
You need to use the {{ic|--force}} option to allow usage of blocklists and should not use {{ic|1=--grub-setup=/bin/true}} (which is similar to simply generating {{ic|core.img}}).<br />
<br />
{{ic|grub-install}} will give out warnings like which should give you the idea of what might go wrong with this approach:<br />
<br />
/sbin/grub-setup: warn: Attempting to install GRUB to a partitionless disk or to a partition. This is a BAD idea.<br />
/sbin/grub-setup: warn: Embedding is not possible. GRUB can only be installed in this setup by using blocklists. <br />
However, blocklists are UNRELIABLE and their use is discouraged.<br />
<br />
Without {{ic|--force}} you may get the below error and {{ic|grub-setup}} will not setup its boot code in the partition boot sector:<br />
<br />
/sbin/grub-setup: error: will not proceed with blocklists<br />
<br />
With {{ic|--force}} you should get:<br />
<br />
Installation finished. No error reported.<br />
<br />
The reason why {{ic|grub-setup}} does not by default allow this is because in case of partition or a partitionless disk is that {{ic|grub-bios}} relies on embedded blocklists in the partition bootsector to locate the {{ic|/boot/grub/i386-pc/core.img}} file and the prefix dir {{ic|/boot/grub}}. The sector locations of {{ic|core.img}} may change whenever the filesystem in the partition is being altered (files copied, deleted etc.). For more info see https://bugzilla.redhat.com/show_bug.cgi?id=728742 and https://bugzilla.redhat.com/show_bug.cgi?id=730915.<br />
<br />
The workaround for this is to set the immutable flag on {{ic|/boot/grub/i386-pc/core.img}} (using chattr command as mentioned above) so that the sector locations of the {{ic|core.img}} file in the disk is not altered. The immutable flag on {{ic|/boot/grub/i386-pc/core.img}} needs to be set only if {{ic|grub-bios}} is installed to a partition boot sector or a partitionless disk, not in case of installtion to MBR or simple generation of {{ic|core.img}} without embedding any bootsector (mentioned above).<br />
<br />
====== Generate core.img alone ======<br />
<br />
To populate the {{ic|/boot/grub}} directory and generate a {{ic|/boot/grub/i386-pc/core.img}} file '''without''' embedding any {{ic|grub-bios}} bootsector code in the MBR, post-MBR region, or the partition bootsector, add {{ic|1=--grub-setup=/bin/true}} to {{ic|grub-install}}:<br />
<br />
# grub-install --directory=/usr/lib/grub/i386-pc --target=i386-pc --grub-setup=/bin/true --boot-directory=/boot --recheck --debug /dev/sda<br />
# mkdir -p /boot/grub/locale<br />
# cp /usr/share/locale/en@quot/LC_MESSAGES/grub.mo /boot/grub/locale/en.mo<br />
<br />
You can then chainload GRUB2's {{ic|core.img}} from GRUB Legacy or syslinux as a Linux kernel or a multiboot kernel.<br />
<br />
===== Generate GRUB2 BIOS Config file =====<br />
<br />
Finally, generate a configuration for GRUB2 (this is explained in greater detail in the Configuration section):<br />
<br />
# grub-mkconfig -o /boot/grub/grub.cfg<br />
<br />
{{Note|The file path is {{ic|/boot/grub/grub.cfg}}, NOT {{ic|/boot/grub/i386-pc/grub.cfg}}.}}<br />
<br />
If grub2 complains about "no suitable mode found" while booting, go to [[#Correct_GRUB2_No_Suitable_Mode_Found_Error]].<br />
<br />
If {{ic|grub-mkconfig}} fails, convert your {{ic|/boot/grub/menu.lst}} file to {{ic|/boot/grub/grub.cfg}} using:<br />
<br />
# grub-menulst2cfg /boot/grub/menu.lst /boot/grub/grub.cfg<br />
<br />
For example:<br />
<br />
{{hc|/boot/grub/menu.lst|<nowiki><br />
default=0<br />
timeout=5<br />
<br />
title Arch Linux Stock Kernel<br />
root (hd0,0)<br />
kernel /vmlinuz-linux root=/dev/sda2 ro<br />
initrd /initramfs-linux.img<br />
<br />
title Arch Linux Stock Kernel Fallback<br />
root (hd0,0)<br />
kernel /vmlinuz-linux root=/dev/sda2 ro<br />
initrd /initramfs-linux-fallback.img<br />
</nowiki>}}<br />
<br />
{{hc|/boot/grub/grub.cfg|<nowiki><br />
set default='0'; if [ x"$default" = xsaved ]; then load_env; set default="$saved_entry"; fi<br />
set timeout=5<br />
<br />
menuentry 'Arch Linux Stock Kernel' {<br />
set root='(hd0,1)'; set legacy_hdbias='0'<br />
legacy_kernel '/vmlinuz-linux' '/vmlinuz-linux' 'root=/dev/sda2' 'ro'<br />
legacy_initrd '/initramfs-linux.img' '/initramfs-linux.img'<br />
<br />
}<br />
<br />
menuentry 'Arch Linux Stock Kernel Fallback' {<br />
set root='(hd0,1)'; set legacy_hdbias='0'<br />
legacy_kernel '/vmlinuz-linux' '/vmlinuz-linux' 'root=/dev/sda2' 'ro'<br />
legacy_initrd '/initramfs-linux-fallback.img' '/initramfs-linux-fallback.img'<br />
}<br />
</nowiki>}}<br />
<br />
If you forgot to create a GRUB2 {{ic|/boot/grub/grub.cfg}} config file and simply rebooted into GRUB2 Command Shell, type:<br />
<br />
sh:grub> insmod legacycfg<br />
sh:grub> legacy_configfile ${prefix}/menu.lst<br />
<br />
Boot into Arch and re-create the proper GRUB2 {{ic|/boot/grub/grub.cfg}} config file.<br />
<br />
{{Note|This option works only in BIOS systems, not in UEFI systems.}}<br />
<br />
===== Multiboot in BIOS =====<br />
<br />
====== Boot Microsoft Windows installed in BIOS-MBR mode ======<br />
<br />
{{Note|GRUB2 supports booting {{ic|bootmgr}} directly and chainload of partition boot sector is no longer required to boot Windows in a BIOS-MBR setup.}}<br />
<br />
Find the UUID of the NTFS filesystem of the Windows's SYSTEM PARTITION where the {{ic|bootmgr}} and its files reside. For example, if Windows {{ic|bootmgr}} exists at {{ic|/media/Windows/bootmgr}}:<br />
<br />
# grub-probe --target=fs_uuid /media/Windows/bootmgr<br />
69B235F6749E84CE<br />
<br />
Then, add the below code to {{ic|/etc/grub.d/40_custom}} and regenerate {{ic|grub.cfg}} with {{ic|grub-mkconfig}} as explained above to boot Windows (Vista, 7 or 8) installed in BIOS-MBR mode:<br />
<br />
<pre><br />
#!/bin/sh<br />
menuentry "Microsoft Windows 7 BIOS-MBR" {<br />
insmod part_msdos<br />
insmod ntfs<br />
insmod search_fs_uuid<br />
insmod ntldr <br />
search --fs-uuid --no-floppy --set=root 69B235F6749E84CE<br />
ntldr /bootmgr<br />
}</pre><br />
<br />
For Windows XP:<br />
<br />
menuentry "Microsoft Windows XP" {<br />
insmod part_msdos<br />
insmod ntfs<br />
insmod search_fs_uuid<br />
insmod ntldr <br />
search --fs-uuid --no-floppy --set=root 69B235F6749E84CE<br />
ntldr /ntldr<br />
}<br />
<br />
==== UEFI systems ====<br />
<br />
{{Note|It is recommended to read the [[UEFI]], [[GPT]] and [[UEFI_Bootloaders]] pages before reading this part.}}<br />
<br />
===== Install grub-uefi package =====<br />
<br />
{{Note|Unless specified as EFI 1.x , EFI and UEFI terms are used interchangeably to denote UEFI 2.x firmware. Also unless stated explicitely, the instructions are general and not Mac specific. Some of them may not work or may be different in Macs. Apple's EFI implementation is neither a EFI 1.x version nor UEFI 2.x version but mixes up both. This kind of firmware does not fall under any one UEFI Specification version and is therefore not a standard UEFI firmware.}}<br />
<br />
GRUB2 UEFI bootloader is available in Arch Linux only from version 1.99~rc1. To install, first [[Unified_Extensible_Firmware_Interface#Detecting_UEFI_Firmware_Arch|detect which UEFI firmware arch]] you have (either x86_64 or i386).<br />
<br />
Depending on that, install the appropriate package<br />
<br />
For 64-bit aka x86_64 UEFI firmware:<br />
# pacman -S grub-efi-x86_64<br />
<br />
For 32-bit aka i386 UEFI firmware:<br />
# pacman -S grub-efi-i386<br />
<br />
{{Note|Simply installing the package will not update the {{ic|grub.efi}} file and the GRUB(2) modules in the UEFI System Partition. You need to do this manually using {{ic|grub-install}} as explained below.}}<br />
<br />
Also load the device-mapper kernel module without which {{ic|grub-probe}} does not reliably detect disks and partitions:<br />
<br />
# modprobe dm-mod<br />
<br />
===== Install grub-uefi boot files =====<br />
<br />
====== Install to UEFI SYSTEM PARTITION ======<br />
<br />
{{Note|The below commands assume you are using {{ic|grub-efi-x86_64}} (for {{ic|grub-efi-i386}} replace {{ic|x86_64}} with {{ic|i386}} in the below commands).}}<br />
<br />
The UEFI system partition will need to be mounted at {{ic|/boot/efi/}} for the GRUB2 install script to detect it:<br />
<br />
# mkdir -p /boot/efi<br />
# mount -t vfat /dev/sdXY /boot/efi<br />
<br />
Install GRUB UEFI application to {{ic|/boot/efi/EFI/arch_grub}} and its modules to {{ic|/boot/grub/x86_64-efi}} (recommended) using:<br />
<br />
# grub-install --directory=/usr/lib/grub/x86_64-efi --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=arch_grub --boot-directory=/boot --recheck --debug<br />
# mkdir -p /boot/grub/locale<br />
# cp /usr/share/locale/en\@quot/LC_MESSAGES/grub.mo /boot/grub/locale/en.mo<br />
<br />
If you want to install grub2 modules and {{ic|grub.cfg}} at the directory {{ic|/boot/efi/EFI/grub}} and the {{ic|grubx64.efi}} application at {{ic|/boot/efi/EFI/arch_grub}} use:<br />
<br />
# grub-install --directory=/usr/lib/grub/x86_64-efi --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=arch_grub --boot-directory=/boot/efi/EFI --recheck --debug<br />
# mkdir -p /boot/efi/EFI/grub/locale<br />
# cp /usr/share/locale/en\@quot/LC_MESSAGES/grub.mo /boot/efi/EFI/grub/locale/en.mo<br />
<br />
In this case {{ic|grub-efi-x86_64}} will be installed into {{ic|/boot/grub}}, making the behavior consistent with the BIOS verion of GRUB2, but this is not recommended if you use both {{ic|grub-bios}} and {{ic|grub-efi-x86_64}} in your system, as this will overwrite {{ic|grub-bios }}modules in {{ic|/boot/grub}}.<br />
<br />
The {{ic|--efi-directory}} option mentions the mountpoint of UEFI SYSTEM PARTITION , {{ic|--bootloader-id}} mentions the name of the directory used to store the {{ic|grubx64.efi}} file and {{ic|--boot-directory}} mentions the directory wherein the actual modules will be installed (and into which {{ic|grub.cfg}} should be created).<br />
<br />
The actual paths are:<br />
<br />
<efi-directory>/<EFI or efi>/<bootloader-id>/grubx64.efi<br />
<br />
<boot-directory>/grub/x86_64-efi/<all modules, grub.efi, core.efi, grub.cfg><br />
<br />
{{Note|the {{ic|--bootloader-id}} option does not change {{ic|<boot-directory>/grub}}, i.e. you cannot install the modules to {{ic|<boot-directory>/<bootloader-id>}}, the path is hard-coded to be {{ic|<boot-directory>/grub}}.}}<br />
<br />
In {{ic|<nowiki>--efi-directory=/boot/efi --boot-directory=/boot/efi/EFI --bootloader-id=grub</nowiki>}}:<br />
<br />
<efi-directory>/<EFI or efi>/<bootloader-id> == <boot-directory>/grub == /boot/efi/EFI/grub<br />
<br />
In {{ic|<nowiki>--efi-directory=/boot/efi --boot-directory=/boot/efi/EFI --bootloader-id=arch_grub</nowiki>}}:<br />
<br />
<efi-directory>/<EFI or efi>/<bootloader-id> == /boot/efi/EFI/arch_grub<br />
<boot-directory>/grub == /boot/efi/EFI/grub<br />
<br />
In {{ic|<nowiki>--efi-directory=/boot/efi --boot-directory=/boot --bootloader-id=arch_grub</nowiki>}}:<br />
<br />
<efi-directory>/<EFI or efi>/<bootloader-id> == /boot/efi/EFI/arch_grub<br />
<boot-directory>/grub == /boot/grub<br />
<br />
In {{ic|<nowiki>--efi-directory=/boot/efi --boot-directory=/boot --bootloader-id=grub</nowiki>}}:<br />
<br />
<efi-directory>/<EFI or efi>/<bootloader-id> == /boot/efi/EFI/grub<br />
<boot-directory>/grub == /boot/grub<br />
<br />
The {{ic|<nowiki><efi-directory>/<EFI or efi>/<bootloader-id>/grubx64.efi</nowiki>}} is an exact copy of {{ic|<nowiki><boot-directory>/grub/x86_64-efi/core.efi</nowiki>}}.<br />
<br />
{{Note|In GRUB2 2.00~beta4, the {{ic|grub-install}} option {{ic|--efi-directory}} replaces {{ic|--root-directory}} and the latter is deprecated.}}<br />
{{Note|The options {{ic|--efi-directory}} and {{ic|--bootloader-id}} are specific to GRUB2 UEFI.}}<br />
<br />
In all the cases the UEFI SYSTEM PARTITION should be mounted for {{ic|grub-install}} to install {{ic|grubx64.efi}} in it, which will be launched by the firmware (using the {{ic|efibootmgr}} created boot entry in non-Mac systems).<br />
<br />
If you notice carefully, there is no <device_path> option (Eg: {{ic|/dev/sda}}) at the end of the {{ic|grub-install}} command unlike the case of setting up GRUB2 for BIOS systems. Any <device_path> provided will be ignored by the install script as UEFI bootloaders do not use MBR or Partition boot sectors at all.<br />
<br />
You may now be able to UEFI boot your system by creating a {{ic|grub.cfg}} file by following [[#Generate_GRUB2_UEFI_Config_file]] and [[#Create_GRUB2_entry_in_the_Firmware_Boot_Manager]].<br />
<br />
===== Create GRUB2 entry in the Firmware Boot Manager =====<br />
<br />
====== Non-Mac UEFI systems ======<br />
<br />
{{ic|grub-install}} will ensure that {{ic|/boot/efi/EFI/arch_grub/grubx64.efi}} is launched by default if it detects {{ic|efibootmgr}} and if it is able to access UEFI Runtime Services. Follow [[Unified_Extensible_Firmware_Interface#efibootmgr]] for more info.<br />
<br />
If you have problems running GRUB2 in UEFI mode you can try the following (worked on an ASUS Z68 mainboard):<br />
<br />
# cp /boot/efi/EFI/arch_grub/grubx64.efi /boot/efi/shellx64.efi<br />
<br />
or<br />
<br />
# cp /boot/efi/EFI/arch_grub/grubx64.efi /boot/efi/EFI/shellx64.efi<br />
<br />
or<br />
<br />
# cp /boot/efi/EFI/arch_grub/grubx64.efi /boot/efi/EFI/tools/shellx64.efi<br />
<br />
After this launch the UEFI Shell from the UEFI setup/menu (in ASUS UEFI BIOS, switch to advanced mode, press Exit in the top right corner and choose "Launch EFI shell from filesystem device"). The GRUB2 menu will show up and you can boot into your system. Afterwards you can use efibootmgr to setup a menu entry (see above).<br />
<br />
====== Apple Mac EFI systems ======<br />
<br />
{{Note|TODO: GRUB upstream Bazaar mactel branch http://bzr.savannah.gnu.org/lh/grub/branches/mactel/changes. No further update from grub developers.}}<br />
{{Note|TODO: Experimental "bless" utility for Linux by Fedora developers - {{AUR|mactel-boot}}. Requires more testing.}}<br />
<br />
Use bless command from within Mac OS X to set {{ic|grubx64.efi}} as the default boot option. You can also boot from the Mac OS X install disc and launch a Terminal there if you only have Linux installed. In the Terminal, create a directory and mount the EFI System Partition:<br />
<br />
# cd /Volumes<br />
# mkdir efi<br />
# mount -t msdos /dev/disk0s1 /Volumes/efi<br />
<br />
Then run bless on {{ic|grub.efi}} and on the EFI partition to set them as the default boot options.<br />
<br />
# bless --folder=/Volumes/efi --file=/Volumes/efi/efi/arch_grub/grubx64.efi --setBoot<br />
# bless --mount=/Volumes/efi --file=/Volumes/efi/efi/arch_grub/grubx64.efi --setBoot<br />
<br />
More info at https://help.ubuntu.com/community/UEFIBooting#Apple_Mac_EFI_systems_.28both_EFI_architecture.29.<br />
<br />
===== Generate GRUB2 UEFI Config file =====<br />
<br />
Finally, generate a configuration for GRUB2 (this is explained in greater detail in the Configuration section):<br />
<br />
# grub-mkconfig -o <boot-directory>/grub/grub.cfg<br />
<br />
{{Note|The file path is {{ic|<boot-directory>/grub/grub.cfg}}, NOT {{ic|<boot-directory>/grub/x86_64-efi/grub.cfg}}.}}<br />
<br />
If you used {{ic|<nowiki>--boot-directory=/boot</nowiki>}}:<br />
<br />
# grub-mkconfig -o /boot/grub/grub.cfg<br />
<br />
If you used {{ic|<nowiki>--boot-directory=/boot/efi/EFI</nowiki>}}:<br />
<br />
# grub-mkconfig -o /boot/efi/EFI/grub/grub.cfg<br />
<br />
This is independent of the value of {{ic|--bootloader-id}} option.<br />
<br />
If GRUB2 complains about "no suitable mode found" while booting, try [[#Correct_GRUB2_No_Suitable_Mode_Found_Error]].<br />
<br />
===== Create GRUB2 Standalone UEFI Application =====<br />
<br />
It is possible to create a {{ic|grubx64_standalone.efi}} application which has all the modules embeddded in a memdisk within the uefi application, thus removing the need for having a separate directory populated with all the GRUB2 uefi modules and other related files. This is done using the {{ic|grub-mkstandalone}} command which is included in {{Pkg|grub-common}} >= 1:1.99-6 package.<br />
<br />
The easiest way to do this would be with the install command already mentioned before, but specifying the modules to include. For example:<br />
<br />
# grub-mkstandalone --directory="/usr/lib/grub/x86_64-efi/" --format="x86_64-efi" --compression="xz" \<br />
--output="/boot/efi/EFI/arch_grub/grubx64_standalone.efi" <any extra files you want to include><br />
<br />
The {{ic|grubx64_standalone.efi}} file expects {{ic|grub.cfg}} to be within its $prefix which is {{ic|(memdisk)/boot/grub}}. The memdisk is embedded within the efi app. The {{ic|grub-mkstandlone}} script allow passing files to be included in the memdisk image to be as the arguments to the script (in <any extra files you want to include>).<br />
<br />
If you have the {{ic|grub.cfg}} at {{ic|/home/user/Desktop/grub.cfg}}, then create a temporary {{ic|/home/user/Desktop/boot/grub/}} directory, copy the {{ic|/home/user/Desktop/grub.cfg}} to {{ic|/home/user/Desktop/boot/grub/grub.cfg}}, cd into {{ic|/home/user/Desktop/boot/grub/}} and run:<br />
<br />
# grub-mkstandalone --directory="/usr/lib/grub/x86_64-efi/" --format="x86_64-efi" --compression="xz" \<br />
--output="/boot/efi/EFI/arch_grub/grubx64_standalone.efi" "boot/grub/grub.cfg"<br />
<br />
The reason to cd into {{ic|/home/user/Desktop/boot/grub/}} and to pass the file path as {{ic|boot/grub/grub.cfg}} (notice the lack of a leading slash - boot/ vs /boot/ ) is because {{ic|dir1/dir2/file}} is included as {{ic|(memdisk)/dir1/dir2/file}} by the {{ic|grub-mkstandalone}} script. <br />
<br />
If you pass {{ic|/home/user/Desktop/grub.cfg}} the file will be included as {{ic|(memdisk)/home/user/Desktop/grub.cfg}}. If you pass {{ic|/home/user/Desktop/boot/grub/grub.cfg}} the file will be included as {{ic|(memdisk)/home/user/Desktop/boot/grub/grub.cfg}}. That is the reason for cd'ing into {{ic|/home/user/Desktop/boot/grub/}} and passing {{ic|boot/grub/grub.cfg}}, to include the file as {{ic|(memdisk)/boot/grub/grub.cfg}}, which is what {{ic|grub.efi}} expects the file to be.<br />
<br />
You need to create an UEFI Boot Manager entry for {{ic|/boot/efi/EFI/arch_grub/grubx64_standalone.efi}} using {{ic|efibootmgr}}. Follow [[#Create GRUB2 entry in the Firmware Boot Manager]].<br />
<br />
===== Multiboot in UEFI =====<br />
<br />
====== Chainload Microsoft Windows x86_64 UEFI-GPT ======<br />
<br />
Find the UUID of the FAT32 filesystem in the UEFI SYSTEM PARTITION where the Windows UEFI Bootloader files reside. For example, if Windows {{ic|bootmgfw.efi}} exists at {{ic|/boot/efi/EFI/Microsoft/Boot/bootmgfw.efi}} (ignore the upper-lower case differences since that is immaterial in FAT filesystem):<br />
<br />
# grub-probe --target=fs_uuid /boot/efi/EFI/Microsoft/Boot/bootmgfw.efi<br />
1ce5-7f28<br />
<br />
# grub-probe --target=hints_string /boot/efi/EFI/Microsoft/Boot/bootmgfw.efi<br />
--hint-bios=hd0,gpt1 --hint-efi=hd0,gpt1 --hint-baremetal=ahci0,gpt1<br />
<br />
Then, add this code to {{ic|/boot/grub/grub.cfg}} OR {{ic|/boot/efi/EFI/grub/grub.cfg}} to chainload Windows x86_64 (Vista SP1+, 7 or 8) installed in UEFI-GPT mode:<br />
<br />
menuentry "Microsoft Windows x86_64 UEFI-GPT" {<br />
insmod part_gpt<br />
insmod fat<br />
insmod search_fs_uuid<br />
insmod chain<br />
search --fs-uuid --no-floppy --set=root --hint-bios=hd0,gpt1 --hint-efi=hd0,gpt1 --hint-baremetal=ahci0,gpt1 1ce5-7f28<br />
chainloader /efi/Microsoft/Boot/bootmgfw.efi<br />
}<br />
<br />
== Configuration ==<br />
<br />
You can also choose to automatically generate or manually edit {{ic|grub.cfg}}.<br />
<br />
{{Note|For EFI systems, if GRUB2 was installed with the {{ic|--boot-directory}} option set, the {{ic|grub.cfg}} file must be placed in the same directory as {{ic|grubx64.efi}}. Otherwise, the {{ic|grub.cfg}} file goes in {{ic|/boot/grub/}}, just like in the BIOS version of GRUB2.}}<br />
<br />
{{Note|Here is a quite complete description of how to configure GRUB2: http://members.iinet.net/~herman546/p20/GRUB2%20Configuration%20File%20Commands.html }}<br />
<br />
=== Automatically generating using grub-mkconfig (Recommended) ===<br />
<br />
The GRUB2 {{ic|menu.lst}} equivalent configuration files are {{ic|/etc/default/grub}} and {{ic|/etc/grub.d/*}}. {{ic|grub-mkconfig}} uses these files to generate {{ic|grub.cfg}}. By default the script outputs to stdout. To generate a {{ic|grub.cfg}} file run the command:<br />
<br />
# grub-mkconfig -o /boot/grub/grub.cfg<br />
<br />
{{ic|/etc/grub.d/10_linux}} is set to automatically add menu items for Arch linux that work out of the box, to any generated configuration. Other operating systems may need to be added manually by editing {{ic|/etc/grub.d/40_custom}}<br />
<br />
==== Additional arguments ====<br />
<br />
To pass custom additional arguments to the Linux image, you can set the {{ic|GRUB_CMDLINE_LINUX}} variable in {{ic|/etc/default/grub}}. This is analogous to adding commands to the kernel line in GRUB Legacy.<br />
<br />
For example, use {{ic|<nowiki>GRUB_CMDLINE_LINUX="resume=/dev/sdaX"</nowiki>}} where {{ic|sda'''X'''}} is your swap partition to enable resume after hibernation.<br />
<br />
You can also use {{ic|<nowiki>GRUB_CMDLINE_LINUX="resume=/dev/disk/by-uuid/${swap_uuid}"</nowiki>}}, where {{ic|${swap_uuid} }} is the [[Persistent_block_device_naming|UUID]] of your swap partition.<br />
<br />
=== Manually creating grub.cfg ===<br />
<br />
{{Warning|Editing this file is strongly ''not'' recommended. The file is generated by the {{ic|grub-mkconfig}} command, and it is best to edit your {{ic|/etc/default/grub}} or one of the scripts in the {{ic|/etc/grub.d}} folder.}}<br />
<br />
A basic GRUB config file uses the following options<br />
* {{ic|(hdX,Y)}} is the partition {{ic|Y}} on disk {{ic|X}}, partition numbers starting at 1, disk numbers starting at 0<br />
* {{ic|1=set default=N}} is the default boot entry that is chosen after timeout for user action<br />
* {{ic|1=set timeout=M}} is the time {{ic|M}} to wait in seconds for a user selection before default is booted<br />
* {{ic|<nowiki>menuentry "title" {entry options}</nowiki>}} is a boot entry titled {{ic|title}}<br />
* {{ic|1=set root=(hdX,Y)}} sets the boot partition, where the kernel and GRUB modules are stored (boot need not be a separate partition, and may simply be a directory under the "root" partition ({{ic|/}})<br />
<br />
An example configuration:<br />
<br />
{{hc<br />
|/boot/grub/grub.cfg<br />
|<nowiki><br />
# Config file for GRUB2 - The GNU GRand Unified Bootloader<br />
# /boot/grub/grub.cfg<br />
<br />
# DEVICE NAME CONVERSIONS<br />
#<br />
# Linux Grub<br />
# -------------------------<br />
# /dev/fd0 (fd0)<br />
# /dev/sda (hd0)<br />
# /dev/sdb2 (hd1,2)<br />
# /dev/sda3 (hd0,3)<br />
#<br />
<br />
# Timeout for menu<br />
set timeout=5<br />
<br />
# Set default boot entry as Entry 0<br />
set default=0<br />
<br />
# (0) Arch Linux<br />
menuentry "Arch Linux" {<br />
set root=(hd0,1)<br />
linux /vmlinuz-linux root=/dev/sda3 ro<br />
initrd /initramfs-linux.img<br />
}<br />
<br />
## (1) Windows<br />
#menuentry "Windows" {<br />
#set root=(hd0,3)<br />
#chainloader +1<br />
#}<br />
</nowiki>}}<br />
<br />
=== Dual-booting ===<br />
<br />
{{Note|If you want GRUB2 to automatically search for other systems, you may wish to install {{Pkg|os-prober}}.}}<br />
<br />
==== Using grub-mkconfig ====<br />
The best way to add other entries is editing the {{ic|/etc/grub.d/40_custom}}. The entries in this file will be automatically added when running {{ic|grub-mkconfig}}.<br />
After adding the new lines, run:<br />
# grub-mkconfig -o /boot/grub/grub.cfg <br />
to generate an updated {{ic|grub.cfg}}.<br />
<br />
===== With GNU/Linux =====<br />
<br />
Assuming that the other distro is on partition {{ic|sda2}}:<br />
<br />
menuentry "Other Linux" {<br />
set root=(hd0,2)<br />
linux /boot/vmlinuz (add other options here as required)<br />
initrd /boot/initrd.img (if the other kernel uses/needs one)<br />
}<br />
<br />
===== With FreeBSD =====<br />
<br />
Requires that FreeBSD is installed on a single partition with UFS. Assuming it is installed on {{ic|sda4}}:<br />
<br />
menuentry "FreeBSD" {<br />
set root=(hd0,4)<br />
chainloader +1<br />
}<br />
<br />
===== With Windows =====<br />
<br />
This assumes that your Windows partition is {{ic|sda3}}.<br />
<br />
# (2) Windows XP<br />
menuentry "Windows XP" {<br />
set root=(hd0,3)<br />
chainloader (hd0,3)+1<br />
}<br />
<br />
If the Windows bootloader is on an entirely different hard drive than GRUB, it may be necessary to trick Windows into believing that it is the first hard drive. This was possible in GRUB Legacy with {{ic|map}} and is now done with {{ic|drivemap}}. Assuming GRUB is on {{ic|hd0}} and Windows is on {{ic|hd2}}, you need to add the following after {{ic|set root}}:<br />
<br />
drivemap -s hd0 hd2<br />
<br />
==== With Windows via EasyBCD and NeoGRUB ====<br />
<br />
Since EasyBCD's NeoGRUB currently does not understand the GRUB2 menu format, chainload to it by replacing the contents of your {{ic|C:\NST\menu.lst}} file with lines similar to the following:<br />
<br />
default 0<br />
timeout 1<br />
<br />
title Chainload into GRUB v2<br />
root (hd0,7)<br />
kernel /boot/grub/i386-pc/core.img<br />
<br />
===Visual Configuration===<br />
<br />
In GRUB2 it is possible, by default, to change the look of the menu. Make sure to initialize, if not done already, GRUB2 graphical terminal, gfxterm, with proper video mode, gfxmode, in GRUB2. This can be seen in the section [[#Correct_GRUB2_No_Suitable_Mode_Found_Error]]. This video mode is passed by GRUB2 to the linux kernel via 'gfxpayload' so any visual configurations need this mode in order to be in effect.<br />
<br />
====Setting the framebuffer resolution ====<br />
<br />
GRUB2 can set the framebuffer for both GRUB2 itself and the kernel. The old {{ic|1=vga=}} way is deprecated. The preferred method is editing {{ic|/etc/default/grub}} as the following sample:<br />
<br />
GRUB_GFXMODE=1024x768x32<br />
GRUB_GFXPAYLOAD_LINUX=keep<br />
<br />
To generate the changes, run: <br />
grub-mkconfig -o /boot/grub/grub.cfg<br />
<br />
The {{ic|gfxpayload}} property will make sure the kernel keeps the resolution.<br />
<br />
{{Note|If this example does not work for you try to replace {{ic|1=gfxmode="1024x768x32"}} by {{ic|1=vbemode="0x105"}}. Remember to replace the specified resolution with one suitable for your screen.}}<br />
{{Note|To show all the modes you can use {{ic|1=# hwinfo --framebuffer}} (hwinfo is available in [community]), while at GRUB2 prompt you can use the {{ic|1=vbeinfo}} command.}}<br />
<br />
If this method does not work for you, the deprecated {{ic|1=vga=}} method will still work. Just<br />
add it next to the {{ic|1="GRUB_CMDLINE_LINUX_DEFAULT="}} line in {{ic|/etc/default/grub}}<br />
for eg: {{ic|1="GRUB_CMDLINE_LINUX_DEFAULT="quiet splash vga=792"}} will give you a {{ic|1024x768}} resolution.<br />
<br />
You can choose one of these resolutions: {{ic|640×480}}, {{ic|800×600}}, {{ic|1024×768}}, {{ic|1280×1024}}, {{ic|1600×1200}}<br />
<br />
====915resolution hack ====<br />
<br />
Some times for Intel graphic adapters neither {{ic|1=# hwinfo --framebuffer}} nor {{ic|1=vbeinfo}} will show you the desired resolution. In this case you can use {{ic|915resolution}} hack. This hack will temporarily modify video BIOS and add needed resolution. See [http://915resolution.mango-lang.org/ 915resolution's home page]<br />
<br />
In the following I will proceed with the example for my system. Please adjust the recipe for your needs. First you need to find a video mode which will be modified later. For that, run {{ic|915resolution}} in GRUB2 command shell:<br />
915resolution -l<br />
The output will be something like:<br />
Intel 800/900 Series VBIOS Hack : version 0.5.3<br />
...<br />
Mode 30 : 640x480, 8 bits/pixel<br />
...<br />
Next, our purpose is to overwrite mode 30. (You can choose what ever mode you want.) In the file {{ic|/etc/grub.d/00_header}} just before the {{ic|set gfxmode&#61;${GRUB_GFXMODE}}} line insert:<br />
915resolution 30 1440 900<br />
Here we are overwriting the mode {{ic|30}} with {{ic|1440x900}} resolution. Lastly we need to set {{ic|GRUB_GFXMODE}} as described earlier, regenerate GRUB2 configuration file and reboot to test changes:<br />
# grub-mkconfig -o /boot/grub/grub.cfg<br />
# reboot<br />
<br />
====Background image and bitmap fonts====<br />
<br />
GRUB2 comes with support for background images and bitmap fonts in {{ic|pf2}} format. The unifont font is included in the {{Pkg|grub-common}} package under the filename {{ic|unicode.pf2}}, or, as only ASCII characters under the name {{ic|ascii.pf2}}. <br />
<br />
Image formats supported include tga, png and jpeg, providing the correct modules are loaded. The maximum supported resolution depends on your hardware.<br />
<br />
Make sure you have set up the proper [https://wiki.archlinux.org/index.php/GRUB2#Setting_the_framebuffer_resolution framebuffer resolution].<br />
<br />
Edit {{ic|/etc/default/grub}} like this:<br />
GRUB_BACKGROUND="/boot/grub/myimage"<br />
#GRUB_THEME="/path/to/gfxtheme"<br />
<br />
{{Note|If you have installed GRUB on a separate partition, {{ic|/boot/grub/myimage}} becomes {{ic|/grub/myimage}}.}}<br />
<br />
To generate the changes and add the information into {{ic|grub.cfg}}, run: <br />
grub-mkconfig -o /boot/grub/grub.cfg<br />
<br />
If adding the splash image was successful, the user will see {{ic|"Found background image..."}} in the terminal as the command is executed. <br />
If this phrase is not seen, the image information was probably not incorporated into the {{ic|grub.cfg}} file.<br />
<br />
If the image is not displayed, check:<br />
* The path and the filename in {{ic|/etc/default/grub}} are correct.<br />
* The image is of the proper size and format (tga, png, 8-bit jpg).<br />
* The image was saved in the RGB mode, and is not indexed.<br />
* The console mode is not enabled in {{ic|/etc/default/grub}}.<br />
* The command {{ic|grub-mkconfig}} must be executed to place the background image information into the {{ic|/boot/grub/grub.cfg}} file.<br />
<br />
====Theme====<br />
<br />
Here is an example for configuring Starfield theme which was included in GRUB2 package.<br />
<br />
Edit {{ic|/etc/default/grub}}<br />
GRUB_THEME="/boot/grub/themes/starfield/theme.txt"<br />
<br />
Generate the changes:<br />
grub-mkconfig -o /boot/grub/grub.cfg<br />
<br />
If configuring the theme was successful, you'll see {{ic|Found theme: /boot/grub/themes/starfield/theme.txt}} in the terminal.<br />
Your splash image will usually not displayed when using a theme.<br />
<br />
====Menu colors====<br />
<br />
As in GRUB Legacy (0.9x), you can change the menu colors in GRUB2. The available colors for GRUB2 are at https://www.gnu.org/software/grub/manual/html_node/Theme-file-format.html#Theme-file-format.<br />
Here is an example:<br />
<br />
Edit {{ic|/etc/default/grub}}:<br />
GRUB_COLOR_NORMAL="light-blue/black"<br />
GRUB_COLOR_HIGHLIGHT="light-cyan/blue"<br />
<br />
Generate the changes:<br />
grub-mkconfig -o /boot/grub/grub.cfg<br />
<br />
====Hidden menu====<br />
<br />
One of the unique features of GRUB2 is hiding/skipping the menu and showing it by holding {{keypress|Shift}} when needed. You can also adjust whether you want to see the timeout counter.<br />
<br />
Edit {{ic|/etc/default/grub}} as you wish. Here is an example where the comments from the beginning of the two lines have been removed to enable the feature, the timeout has been set to five seconds and to be shown to the user:<br />
GRUB_HIDDEN_TIMEOUT=5<br />
GRUB_HIDDEN_TIMEOUT_QUIET=false<br />
<br />
and run:<br />
grub-mkconfig -o /boot/grub/grub.cfg<br />
<br />
=== Other Options ===<br />
<br />
==== LVM ====<br />
<br />
If you use [[LVM]] for your {{ic|/boot}}, add the following before menuentry lines:<br />
<br />
insmod lvm<br />
<br />
and specify your root in the menuentry as:<br />
<br />
set root=(''lvm_group_name''-''lvm_logical_boot_partition_name'')<br />
<br />
Example:<br />
<br />
# (0) Arch Linux<br />
menuentry "Arch Linux" {<br />
insmod lvm<br />
set root=(VolumeGroup-lv_boot)<br />
# you can only set following two lines<br />
linux /vmlinuz-linux root=/dev/mapper/VolumeGroup-root ro<br />
initrd /initramfs-linux.img<br />
}<br />
<br />
==== RAID ====<br />
<br />
GRUB2 provides convenient handling of RAID volumes. You need to add {{ic|insmod raid}} which allows you to address the volume natively. For example, {{ic|/dev/md0}} becomes:<br />
set root=(md0)<br />
<br />
whereas a partitioned RAID volume (e.g. {{ic|/dev/md0p1}}) becomes:<br />
set root=(md0,1)<br />
<br />
==== Persistent block device naming ====<br />
You can use UUIDs to detect partitions instead of the "old" {{ic|/dev/sd*}} and {{ic|/dev/hd*}} scheming. It has the advantage of detecting partitions by their unique UUIDs, which is needed by some people booting with complicated partition setups.<br />
<br />
UUIDs are used by default in the recent versions of GRUB2 - there is no downside in it anyway except that you need to re-generate the {{ic|grub.cfg}} file every time you resize or reformat your partitions. Remember this when modifying partitions with Live-CD.<br />
<br />
The recent versions of GRUB2 use UUIDs by default. You can re-enable the use of UUIDS by simply commenting the UUID line (this is also what it looks like by default):<br />
#GRUB_DISABLE_LINUX_UUID=true<br />
you can also just set the value as {{ic|false}} as shown here:<br />
GRUB_DISABLE_LINUX_UUID=false<br />
<br />
Either way, do not forget to generate the changes:<br />
grub-mkconfig -o /boot/grub/grub.cfg<br />
<br />
==== Using Labels ====<br />
<br />
It is possible to use labels, human-readable strings attached to filesystems, by using the {{ic|--label}} option to {{ic|search}}. First of all, label your existing partition:<br />
# tune2fs -L a <LABEL> <PARTITION><br />
<br />
Then, add an entry using labels. An example of this:<br />
<br />
menuentry "Arch Linux, session texte" {<br />
search --label --no-floppy --set=root archroot<br />
linux /boot/vmlinuz-linux root=/dev/disk/by-label/archroot ro<br />
initrd /boot/initramfs-linux.img<br />
}<br />
<br />
==== Recall previous entry ====<br />
<br />
GRUB2 can remember the last entry you booted from and use this as the default entry to boot from next time. This is useful if you have multiple kernels (i.e., the current Arch one and the LTS kernel as a fallback option) or operating systems. To do this, edit {{ic|/etc/default/grub}} and change the setting of {{ic|GRUB_DEFAULT}}:<br />
<br />
GRUB_DEFAULT=saved<br />
<br />
This ensures that GRUB will default to the saved entry. To enable saving the selected entry, add the following line to {{ic|/etc/default/grub}}:<br />
<br />
GRUB_SAVEDEFAULT=true<br />
<br />
{{Note|Manually added menu items, eg Windows in {{ic|/etc/grub.d/40_custom}}, will need {{ic|savedefault}} added. Remember to regenerate your configuration file.}}<br />
<br />
==== Security ====<br />
<br />
If you want to secure GRUB2 so it is not possible for anyone to change boot parameters or use the command line, you can add a user/password combination to GRUB2's configuration files. To do this, run the command {{ic|grub-mkpasswd_pbkdf2}}. Enter a password and confirm it. The output will look like this:<br />
<br />
{{bc|<nowiki><br />
Your PBKDF2 is grub.pbkdf2.sha512.10000.C8ABD3E93C4DFC83138B0C7A3D719BC650E6234310DA069E6FDB0DD4156313DA3D0D9BFFC2846C21D5A2DDA515114CF6378F8A064C94198D0618E70D23717E82.509BFA8A4217EAD0B33C87432524C0B6B64B34FBAD22D3E6E6874D9B101996C5F98AB1746FE7C7199147ECF4ABD8661C222EEEDB7D14A843261FFF2C07B1269A</nowiki>}}Then, add the following to {{ic|/etc/grub.d/00_header}}:<br />
{{bc|<nowiki>cat << EOF<br />
<br />
set superusers="username"<br />
password_pbkdf2 username <password><br />
<br />
EOF</nowiki>}}<br />
where {{ic|<password>}} is the string generated by {{ic|grub-mkpasswd_pbkdf2}}.<br />
<br />
Regenerate your configuration file. Your GRUB2 command line, boot parameters and all boot entries are now protected.<br />
<br />
This can be relaxed and further customized with more users as described in the "Security" part of [https://www.gnu.org/software/grub/manual/grub.html#Security the GRUB manual].<br />
<br />
==== Root Encryption ====<br />
<br />
To let GRUB2 automatically add the kernel parameters for root encryption,<br />
add {{ic|1=cryptdevice=/dev/yourdevice:label}} to {{ic|GRUB_CMDLINE_LINUX}} in {{ic|/etc/defaults/grub}}.<br />
<br />
Example with root mapped to {{ic|/dev/mapper/root}}:<br />
<br />
GRUB_CMDLINE_LINUX="cryptdevice=/dev/sda2:root"<br />
<br />
Also, disable the usage of UUIDs for the rootfs:<br />
<br />
GRUB_DISABLE_LINUX_UUID=true<br />
<br />
Regenerate the configuration.<br />
<br />
=== Booting an ISO Directly From GRUB2 ===<br />
Edit {{ic|/etc/grub.d/40_custom}} to add an entry for the target ISO. When finished, update the GRUB menu as with the usual {{ic|grub-mkconfig -o /boot/grub/grub.cfg}} (as root).<br />
<br />
==== Arch ISO ====<br />
{{Note|Be sure to adjust the {{ic|hdX,Y}} in the third line to point to the correct disk/partition number of the isofile. Also adjust the {{ic|img_dev}} line to match this same location. However, if booting the ISO from USB on a computer which also has one internal HDD, then it needs to be {{ic|hd0,Y}} with {{ic|sdbY}}, instead of {{ic|sdaY}}.}}<br />
<br />
menuentry "Archlinux-2011.08.19-netinstall-x86_64.iso" {<br />
set isofile="/archives/archlinux-2011.08.19-netinstall-x86_64.iso"<br />
loopback loop (hd0,7)$isofile<br />
linux (loop)/arch/boot/x86_64/vmlinuz archisolabel=ARCH_201108 img_dev=/dev/sda7 img_loop=$isofile earlymodules=loop<br />
initrd (loop)/arch/boot/x86_64/archiso.img<br />
}<br />
<br />
==== Ubuntu ISO ====<br />
{{Note|Be sure to adjust the {{ic|hdX,Y}} in the third line to point to the correct disk or partition number of the ISO file.}}<br />
<br />
menuentry "ubuntu-12.04-desktop-amd64.iso" {<br />
set isofile="/path/to/ubuntu-12.04-desktop-amd64.iso"<br />
loopback loop (hdX,Y)$isofile<br />
linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile quiet noeject noprompt splash --<br />
initrd (loop)/casper/initrd.lz<br />
}<br />
<br />
== Using the command shell ==<br />
<br />
Since the MBR is too small to store all GRUB2 modules, only the menu and a few basic commands reside there. The majority of GRUB2 functionality remains in modules in {{ic|/boot/grub}}, which are inserted as needed. In error conditions (e.g. if the partition layout changes) GRUB2 may fail to boot. When this happens, a command shell may appear.<br />
<br />
GRUB2 offers multiple shells/prompts. If there is a problem reading the menu but the bootloader is able to find the disk, you will likely be dropped to the "normal" shell:<br />
sh:grub><br />
<br />
If there is a more serious problem (e.g. GRUB cannot find required files), you may instead be dropped to the "rescue" shell:<br />
grub rescue><br />
<br />
The rescue shell is a restricted subset of the normal shell, offering much less functionality. If dumped to the rescue shell, first try inserting the "normal" module, then starting the "normal" shell:<br />
grub rescue> set prefix=(hdX,Y)/boot/grub<br />
grub rescue> insmod (hdX,Y)/boot/grub/i386-pc/normal.mod<br />
rescue:grub> normal<br />
<br />
=== Pager support ===<br />
<br />
GRUB2 supports pager for reading commands that provide long output (like the help command). This works only in normal shell mode and not in rescue mode. To enable pager, in GRUB2 command shell type:<br />
sh:grub> set pager=1<br />
<br />
== GUI configuration tools ==<br />
<br />
Following package may be installed from [[AUR]]<br />
* [https://aur.archlinux.org/packages.php?ID=44020 grub-customizer] (requires gettext gksu gtkmm hicolor-icon-theme openssl)<br />
*:Customize the bootloader (GRUB2 or BURG)<br />
* [http://kde-apps.org/content/show.php?content=139643 grub2-editor] (requires kdelibs)<br />
*:A KDE4 control module for configuring the GRUB2 bootloader<br />
* [http://kde-apps.org/content/show.php?content=137886 kcm-grub2] (requires kdelibs python2-qt kdebindings-python)<br />
*:This Kcm module manages the most common settings of Grub2.<br />
* [http://sourceforge.net/projects/startup-manager/ startupmanager] (requires gnome-python imagemagick yelp python2 xorg-xrandr)<br />
*:GUI app for changing the settings of GRUB, GRUB2, Usplash and Splashy<br />
<br />
== parttool or legacy hide/unhide ==<br />
<br />
If you have a Windows 9x paradigm with hidden C:\ disks GRUB Legacy had the hide/unhide feature. In GRUB2 this has been replaced by {{ic|parttool}}. For example, to boot the third C:\ disk of three Windows 9x installations on the CLI enter the CLI and:<br />
parttool hd0,1 hidden+ boot-<br />
parttool hd0,2 hidden+ boot-<br />
parttool hd0,3 hidden- boot+<br />
set root=hd0,3<br />
chainloader +1<br />
boot<br />
<br />
== Using the rescue console ==<br />
<br />
See [[#Using the command shell]] first. If unable to activate the standard shell, one possible solution is to boot using a live CD or some other rescue disk to correct configuration errors and reinstall GRUB. However, such a boot disk is not always available (nor necessary); the rescue console is surprisingly robust.<br />
<br />
The available commands in GRUB rescue include {{ic|insmod}}, {{ic|ls}}, {{ic|set}}, and {{ic|unset}}. This example uses {{ic|set}} and {{ic|insmod}}. {{ic|set}} modifies variables and {{ic|insmod}} inserts new modules to add functionality.<br />
<br />
Before starting, the user must know the location of their {{ic|/boot}} partition (be it a separate partition, or a subdirectory under their root):<br />
grub rescue> set prefix=(hdX,Y)/boot/grub<br />
<br />
where X is the physical drive number and Y is the partition number.<br />
<br />
To expand console capabilities, insert the {{ic|linux}} module:<br />
grub rescue> insmod (hdX,Y)/boot/grub/linux.mod<br />
<br />
{{Note|With a separate boot partition, omit {{ic|/boot}} from the path, (i.e. type {{ic|1=set prefix=(hdX,Y)/grub}} and {{ic|insmod (hdX,Y)/grub/linux.mod}}).}}<br />
<br />
This introduces the {{ic|linux}} and {{ic|initrd}} commands, which should be familiar (see [[#Configuration]]).<br />
<br />
An example, booting Arch Linux:<br />
set root=(hd0,5)<br />
linux /boot/vmlinuz-linux root=/dev/sda5<br />
initrd /boot/initramfs-linux.img<br />
boot<br />
<br />
With a separate boot partition, again change the lines accordingly:<br />
set root=(hd0,5)<br />
linux /vmlinuz-linux root=/dev/sda6<br />
initrd /initramfs-linux.img<br />
boot<br />
<br />
After successfully booting the Arch Linux installation, users can correct {{ic|grub.cfg}} as needed and then reinstall GRUB2.<br />
<br />
to reinstall GRUB2 and fix the problem completely, changing {{ic|/dev/sda}} if needed. See [[#Bootloader installation]] for details.<br />
<br />
== Combining the use of UUIDs and basic scripting ==<br />
<br />
If you like the idea of using UUIDs to avoid unreliable BIOS mappings or are struggling with GRUB's syntax, here is an example boot menu item that uses UUIDs and a small script to direct GRUB to the proper disk partitions for your system. All you need to do is replace the UUIDs in the sample with the correct UUIDs for your system. The example applies to a system with a boot and root partition. You will obviously need to modify the GRUB configuration if you have additional partitions:<br />
<br />
menuentry "Arch Linux 64" {<br />
# Set the UUIDs for your boot and root partition respectively<br />
set the_boot_uuid=ece0448f-bb08-486d-9864-ac3271bd8d07<br />
set the_root_uuid=c55da16f-e2af-4603-9e0b-03f5f565ec4a<br />
<br />
# (Note: This may be the same as your boot partition)<br />
<br />
# Get the boot/root devices and set them in the root and grub_boot variables<br />
search --fs-uuid --no-floppy --set=root $the_root_uuid<br />
search --fs-uuid --no-floppy --set=grub_boot $the_boot_uuid<br />
<br />
# Check to see if boot and root are equal.<br />
# If they are, then append /boot to $grub_boot (Since $grub_boot is actually the root partition)<br />
if [ $the_boot_uuid == $the_root_uuid] ; then<br />
set grub_boot=$grub_boot/boot<br />
fi<br />
<br />
# $grub_boot now points to the correct location, so the following will properly find the kernel and initrd<br />
linux ($grub_boot)/vmlinuz-linux root=/dev/disk/by-uuid/$uuid_os_root ro<br />
initrd ($grub_boot)/initramfs-linux.img<br />
}<br />
<br />
== Troubleshooting ==<br />
<br />
Any troubleshooting should be added here.<br />
<br />
=== Enable GRUB2 debug messages ===<br />
<br />
Add:<br />
<br />
set pager=1<br />
set debug=all<br />
<br />
to {{ic|grub.cfg}}.<br />
<br />
=== Correct GRUB2 No Suitable Mode Found Error ===<br />
<br />
If you get this error when booting any menuentry:<br />
<br />
error: no suitable mode found<br />
Booting however<br />
<br />
Then you need to initialize GRUB2 graphical terminal ({{ic|gfxterm}}) with proper video mode ({{ic|gfxmode}}) in GRUB2. This video mode is passed by GRUB2 to the linux kernel via 'gfxpayload'. In case of UEFI systems, if the GRUB2 video mode is not initialized, no kernel boot messages will be shown in the terminal (atleast until KMS kicks in).<br />
<br />
Copy {{ic|/usr/share/grub/unicode.pf2}} to ${GRUB2_PREFIX_DIR} ({{ic|/boot/grub/}} in case of BIOS and UEFI systems). If GRUB2 UEFI was installed with {{ic|1=--boot-directory=/boot/efi/EFI}} set, then the directory is {{ic|/boot/efi/EFI/grub/}}:<br />
<br />
# cp /usr/share/grub/unicode.pf2 ${GRUB2_PREFIX_DIR}<br />
<br />
If {{ic|/usr/share/grub/unicode.pf2}} does not exist, install {{Pkg|bdf-unifont}}, create the {{ic|unifont.pf2}} file and then copy it to {{ic|${GRUB2_PREFIX_DIR<nowiki>}</nowiki>}}:<br />
<br />
# grub-mkfont -o unicode.pf2 /usr/share/fonts/misc/unifont.bdf<br />
<br />
Then, in the {{ic|grub.cfg}} file, add the following lines to enable GRUB2 to pass the video mode correctly to the kernel, without of which you will only get a black screen (no output) but booting (actually) proceeds successfully without any system hang.<br />
<br />
BIOS systems:<br />
<br />
insmod vbe<br />
<br />
UEFI systems:<br />
<br />
insmod efi_gop<br />
insmod efi_uga<br />
<br />
After that add the following code (common to both BIOS and UEFI):<br />
<br />
insmod font<br />
<br />
if loadfont ${prefix}/fonts/unicode.pf2<br />
then<br />
insmod gfxterm<br />
set gfxmode=auto<br />
set gfxpayload=keep<br />
terminal_output gfxterm<br />
fi<br />
<br />
As you can see for gfxterm (graphical terminal) to function properly, {{ic|unicode.pf2}} font file should exist in {{ic|${GRUB2_PREFIX_DIR<nowiki>}</nowiki>}}.<br />
<br />
=== msdos-style error message ===<br />
<br />
grub-setup: warn: This msdos-style partition label has no post-MBR gap; embedding won't be possible!<br />
grub-setup: warn: Embedding is not possible. GRUB can only be installed in this setup by using blocklists.<br />
However, blocklists are UNRELIABLE and its use is discouraged.<br />
grub-setup: error: If you really want blocklists, use --force.<br />
<br />
This error may occur when you try installing GRUB2 in a VMware container. Read more about it [https://bbs.archlinux.org/viewtopic.php?pid=581760#p581760 here]. It happens when the first partition starts just after the MBR (block 63), without the usual space of 1 MiB (2048 blocks) before the first partition. Read [[#MBR_aka_msdos_partitioning_specific_instructions]]<br />
<br />
=== UEFI GRUB2 drops to shell ===<br />
<br />
If GRUB loads but drops you into the rescue shell with no errors, it may be because of a missing or misplaced {{ic|grub.cfg}}. This will happen if GRUB2 UEFI was installed with {{ic|--boot-directory}} and {{ic|grub.cfg}} is missing OR if the partition number of the boot partition changed (which is hard-coded into the {{ic|grubx64.efi}} file).<br />
<br />
=== UEFI GRUB2 not loaded ===<br />
In some cases the EFI may fail to load GRUB correctly. Provided everything is set up correctly, the output of:<br />
efibootmgr -v<br />
might look something like this:<br />
BootCurrent: 0000<br />
Timeout: 3 seconds<br />
BootOrder: 0000,0001,0002<br />
Boot0000* Grub HD(1,800,32000,23532fbb-1bfa-4e46-851a-b494bfe9478c)File(\efi\grub\grub.efi)<br />
Boot0001* Shell HD(1,800,32000,23532fbb-1bfa-4e46-851a-b494bfe9478c)File(\EfiShell.efi)<br />
Boot0002* Festplatte BIOS(2,0,00)P0: SAMSUNG HD204UI<br />
If everything works correctly, the EFI would now automatically load GRUB.<br />
<br />
If the screen only goes black for a second and the next boot option is tried afterwards, according to [https://bbs.archlinux.org/viewtopic.php?pid=981560#p981560 this post], moving GRUB to the partition root can help. The boot option has to be deleted and recreated afterwards. The entry for GRUB should look like this then:<br />
Boot0000* Grub HD(1,800,32000,23532fbb-1bfa-4e46-851a-b494bfe9478c)File(\grub.efi)<br />
<br />
=== Invalid signature ===<br />
If trying to boot Windows results in an "invalid signature" error, e.g. after reconfiguring partitions or adding additional hard drives, (re)move GRUB's device configuration and let it reconfigure:<br />
# mv /boot/grub/device.map /boot/grub/device.map-old<br />
# grub-mkconfig -o /boot/grub/grub.cfg<br />
{{ic|grub-mkconfig}} should now mention all found boot options, including Windows. If it works, remove {{ic|/boot/grub/device.map-old}}.<br />
<br />
=== Restore GRUB Legacy ===<br />
<br />
* Move GRUB2 files out of the way:<br />
<br />
# mv /boot/grub /boot/grub.nonfunctional<br />
<br />
* Copy GRUB Legacy back to {{ic|/boot}}:<br />
<br />
# cp -af /boot/grub-legacy /boot/grub<br />
<br />
* Replace MBR and next 62 sectors of sda with backed up copy<br />
<br />
{{Warning|This command also restores the partition table, so be careful of overwriting a modified partition table with the old one. It '''will''' mess your system.}}<br />
<br />
# dd if=/path/to/backup/first-sectors of=/dev/sdX bs=512 count=1<br />
<br />
A safer way is to restore only the MBR boot code use:<br />
<br />
# dd if=/path/to/backup/mbr-boot-code of=/dev/sdX bs=446 count=1<br />
<br />
== References ==<br />
<br />
# Official GRUB2 Manual - https://www.gnu.org/software/grub/manual/grub.html<br />
# Ubuntu wiki page for GRUB2 - https://help.ubuntu.com/community/Grub2<br />
# GRUB2 wiki page describing steps to compile for UEFI systems - https://help.ubuntu.com/community/UEFIBooting<br />
# Wikipedia's page on [[Wikipedia:BIOS Boot partition|BIOS Boot partition]]<br />
<br />
== External Links ==<br />
<br />
# [https://github.com/the-ridikulus-rat/My_Shell_Scripts/blob/master/grub/grub_bios.sh A Linux Bash Shell script to compile and install GRUB(2) for BIOS from BZR Source]<br />
# [https://github.com/the-ridikulus-rat/My_Shell_Scripts/blob/master/grub/grub_uefi.sh A Linux Bash Shell script to compile and install GRUB(2) for UEFI from BZR Source]</div>Ivan p