Can you explain what the file /etc/fstab is and what information it usually contains?

The /etc/fstab file in Linux and Unix systems is a configuration file that contains information about file systems that should be automatically mounted at system startup.

It typically stores the following information for each file system:

• Device or UUID (e.g., /dev/sda1 or UUID=xxxx-xxxx)
• Mount point (e.g., /, /home, /mnt/data)
• File system type (e.g., ext4, xfs, swap)
• Mount options (e.g., defaults, noatime, ro)
• Parameters for the dump command (usually 0 or 1)
• Parameters for file system check at boot (fsck)

Example line from /etc/fstab:

UUID=123e4567-e89b-12d3-a456-426614174000 / ext4 defaults 0 1

This file allows the system to automatically mount necessary partitions and devices at startup without manual intervention.