GitHub

recfstab

Generate fstab entries from mounted filesystems. Like genfstab for Arch Linux.

Overview

recfstab reads mounted filesystems under a root directory and outputs properly formatted fstab entries to stdout. This is the equivalent of Arch Linux's genfstab command.

The output is suitable for appending to /etc/fstab. Pseudo-filesystems (proc, sysfs, tmpfs) are automatically filtered out.

Usage

recfstab [OPTIONS] <ROOT>
Argument Description
ROOT Root directory to scan for mounted filesystems (e.g., /mnt)

Options

Option Description
-L, --label Use filesystem LABEL instead of UUID
-p, --partuuid Use partition UUID (PARTUUID) instead of filesystem UUID
-t, --partlabel Use partition LABEL (PARTLABEL) instead of filesystem UUID
--version Show version
--help Show help

The identifier options (-L, -p, -t) are mutually exclusive. Default is UUID.

Examples

Generate fstab with UUIDs (default) 
recfstab /mnt >> /mnt/etc/fstab
Generate fstab with filesystem LABELs 
recfstab -L /mnt >> /mnt/etc/fstab
Generate fstab with partition UUIDs 
recfstab -p /mnt >> /mnt/etc/fstab
Preview output without writing 
recfstab /mnt

Output Format

Each mount produces a commented device path followed by the fstab entry: 

# /dev/nvme0n1p2
UUID=a1b2c3d4-e5f6-7890-abcd-ef1234567890	/	ext4	rw,relatime	0	1

# /dev/nvme0n1p1
UUID=ABCD-1234	/boot	vfat	rw,relatime,fmask=0022,dmask=0022	0	2

Fields: device identifier, mount point, filesystem type, options, dump, pass

Identifier Types

Type Flag Example Use Case
UUID (default) UUID=a1b2c3d4-... Most reliable for single-disk systems
LABEL -L LABEL=root Human-readable if you label filesystems
PARTUUID -p PARTUUID=12345678-01 GPT partition UUID, survives reformatting
PARTLABEL -t PARTLABEL=EFI GPT partition label if set during partitioning

Filtered Options

Runtime-only mount options are automatically removed from the output since they should not persist in fstab:

  • rw / ro - Read-write/read-only (determined at mount time)
  • seclabel - SELinux label option
  • noatime, relatime - Access time options are preserved

Pseudo-Filesystems

These filesystem types are automatically excluded: 

proc  sysfs  devtmpfs  tmpfs  devpts  securityfs  cgroup  cgroup2
pstore  bpf  tracefs  debugfs  hugetlbfs  mqueue  fusectl  configfs
efivarfs  autofs  fuse.gvfsd-fuse  overlay  squashfs  erofs

Swap Handling

Swap partitions and files under the root are included automatically:

  • Swap partitions - Detected from /proc/swaps, included with priority if set
  • Swap files - Detected and path adjusted relative to root
  • zram - Excluded (runtime-only compressed RAM swap)

Error Codes

Code Description
E001 Root directory does not exist
E002 Path is not a directory
E003 Failed to determine current directory
E004 findmnt command not found (util-linux not installed)
E005 findmnt command failed
E006 No filesystems found under specified root
E007 blkid command not found (util-linux not installed)

Requirements

  • findmnt - Part of util-linux, used to enumerate mounts
  • blkid - Part of util-linux, used to look up device identifiers
  • Root privileges (for blkid to read device UUIDs)

Comparison with genfstab

Feature recfstab genfstab
Identifier types UUID, LABEL, PARTUUID, PARTLABEL Same
Output to stdout Yes Yes
Pseudo-filesystem filtering Automatic Automatic
btrfs subvolumes Supported Supported
Swap detection Automatic Automatic

See Also