One way to view how the UUIDs connect with the device names (e.g., /dev/sda1) is to use the blkid command. Those lengthy device identifiers that you see in /etc/fstab that are labeled UUID (universally unique identifier) are 128 bit (32 hex characters) long and arranged in an 8-4-4-4-12 character sequence. The /etc/fstab file shown above is unusual in that a new OS was just recently installed on /dev/sda and the /home folder from the system before the upgrade (on a separate disk) was then remounted after the first reference to /home was commented out. The btrfs file system is a modern copy-on-write (CoW) filesystem for Linux that provides advanced features while also focusing on fault tolerance, repair and easy administration. determines if file-system checking should be done at boot time (0 = not).determines if the file system might be dumped (0 = not) using the dump command (not often used).shows the file system type (could be ext4, xfs, btrfs, f2fs, vfat, ntfs, hfsplus, tmpfs, sysfs, proc, iso9660, udf, squashfs, nfs, cifs or something else).describes the disk partition (more on the UUIDs below).UUID=d867ced1-8d81-47c6-b299-3365ba8a02de /home ext4 defaultsĮach line in the file (other than the comments) represents a file system and has six fields. # After editing this file, run 'systemctl daemon-reload' to update systemd # See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info. # Accessible filesystems, by reference, are maintained under '/dev/disk/'. # Created by anaconda on Fri Mar 12 12:26:55 2021 Here's an example of an /etc/fstab file on a Fedora system: $ cat /etc/fstab While this file has played an important role over the years, its format has changed with the introduction of UUIDs and, on some systems, a more reliable file-system type. It contains information that allows the system to connect to disk partitions and determine where they should be mounted in the file system. The command also supports several options that allow the user to control the format of the generated UUID, specify a different version of the UUID specification, or use a different random number generator.The /etc/fstab file is a very important file on Linux systems. By default, the command generates a new UUID and prints it to standard output. The uuidgen command is typically used in scripting or programming contexts where a unique identifier is required. The format includes a time-based component that ensures that UUIDs generated at different times are different, as well as a random component that makes it extremely unlikely for two UUIDs generated at the same time to be the same. UUIDs generated by uuidgen conform to the standard format specified in RFC 4122, which defines a UUID as a 128-bit number represented by a sequence of hexadecimal digits, usually separated by hyphens into five groups of varying lengths. These identifiers are used in various applications, such as databases, distributed systems, and network protocols, to provide a reliable way to identify unique objects or entities. Uuidgen is a command-line utility in Unix and Unix-like operating systems that is used to generate unique identifiers known as UUIDs.
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