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fstab options with examples

The /etc/fstab (File System Table) file is used to define how storage devices, partitions, and file systems should be mounted automatically at boot.

1. Viewing the /etc/fstab File

To display the contents of /etc/fstab:

cat /etc/fstab

or

sudo nano /etc/fstab

2. /etc/fstab File Format

Each line in /etc/fstab follows this format:

php-template
<DEVICE> <MOUNT_POINT> <FILESYSTEM> <OPTIONS> <DUMP> <FSCK_ORDER>
Column Description
DEVICE The disk/partition (e.g., /dev/sdb1 or UUID=xxxx).
MOUNT_POINT Directory where it is mounted (e.g., /mnt/data).
FILESYSTEM File system type (ext4, xfs, ntfs, vfat, etc.).
OPTIONS Mount options (defaults, noexec, ro, etc.).
DUMP Backup option (0 = no backup, 1 = backup with dump).
FSCK_ORDER File system check order (0 = no check, 1 = root, 2 = others).

3. Example /etc/fstab Entries

Mount an ext4 Partition

ini
UUID=1234abcd-5678 /mnt/data ext4 defaults 0 2

🔹 Mounts an ext4 file system at /mnt/data with default options.

Mount a Swap Partition

ini
UUID=5678efgh-9101 none swap sw 0 0

🔹 Enables a swap partition.

Mount a Windows NTFS Partition

ini
UUID=abcd1234-efgh-5678 /mnt/windows ntfs-3g defaults 0 0

🔹 Mounts an NTFS partition using ntfs-3g.

Mount a USB Drive (vFAT)

ini
UUID=9F7A-1D2C /mnt/usb vfat defaults,uid=1000,gid=1000 0 0

🔹 Ensures a FAT32 USB drive is mounted with correct permissions.

Mount an NFS Share

192.168.1.100:/shared /mnt/nfs nfs defaults 0 0

🔹 Mounts an NFS share from a remote server.

4. Get Partition UUIDs for /etc/fstab

Use blkid to find UUIDs:

sudo blkid

or

lsblk -o NAME,UUID,MOUNTPOINT

Use these UUIDs in /etc/fstab instead of /dev/sdX for reliability.

5. Apply Changes Without Reboot

To reload /etc/fstab without rebooting:

sudo mount -a

🔹 This mounts all file systems listed in /etc/fstab.

6. Common Mount Options

Option Description
defaults Uses default mount settings (rw, suid, dev, exec, auto, nouser, async).
ro Mount as read-only.
rw Mount as read-write.
noexec Prevents execution of binaries.
nosuid Ignores SUID bit for security.
nofail Continues boot even if the mount fails.
uid=1000,gid=1000 Sets owner to user ID 1000 (useful for USB drives).

7. Troubleshooting /etc/fstab Issues

If a misconfiguration causes boot failure:

  1. Boot into recovery mode or a live Linux USB.
  2. Edit /etc/fstab:
    sudo nano /etc/fstab
  3. Comment out the problematic line by adding # at the beginning.
  4. Save and reboot.

To check for errors before rebooting:

sudo mount -a

✅ Summary

  • /etc/fstab is used for automatic mounting.
  • Use blkid to get UUIDs for reliable mounting.
  • Mounting options affect performance and security.
  • Test changes with sudo mount -a before rebooting.