False positive for a duplicate entry into fstab - how do I fix it?

Matty

12/13/23, 9:24 PM

I have a machine running Ubuntu 22.04.1 LTS and am getting the following errors. I did some digging and in the process, the UUID appeared to update by itself. The UUIDs are unique for each partition. Thanks in advance!

The machine has 2 HDs - here is the partition map:

NAME         MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
loop0          7:0    0     4K  1 loop /snap/bare/5
loop1          7:1    0     9M  1 loop /snap/canonical-livepatch/146
loop2          7:2    0     9M  1 loop /snap/canonical-livepatch/164
loop3          7:3    0 116.7M  1 loop /snap/core/14399
loop4          7:4    0  63.2M  1 loop /snap/core20/1623
loop5          7:5    0  63.2M  1 loop /snap/core20/1738
loop6          7:6    0 237.5M  1 loop /snap/firefox/2154
loop7          7:7    0 238.9M  1 loop /snap/firefox/2186
loop8          7:8    0 346.3M  1 loop /snap/gnome-3-38-2004/115
loop9          7:9    0 346.3M  1 loop /snap/gnome-3-38-2004/119
loop10         7:10   0  91.7M  1 loop /snap/gtk-common-themes/1535
loop11         7:11   0  49.6M  1 loop /snap/snapd/17883
sda            8:0    0 223.6G  0 disk 
├─sda1         8:1    0  46.6G  0 part /var/snap/firefox/common/host-hunspell
│                                      /
├─sda2         8:2    0  29.8G  0 part 
├─sda3         8:3    0  29.8G  0 part /tmp
├─sda4         8:4    0  55.9G  0 part /var
└─sda5         8:5    0  61.5G  0 part /home
mmcblk0      179:0    0   7.3G  0 disk 
├─mmcblk0p1  179:1    0   953M  0 part /boot/efi
├─mmcblk0p2  179:2    0 953.7M  0 part /boot
└─mmcblk0p3  179:3    0   5.4G  0 part /BACKUP
mmcblk0boot0 179:8    0     4M  1 disk 
mmcblk0boot1 179:16   0     4M  1 disk 

# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a device; this may
# be used with UUID= as a more robust way to name devices that works even if
# disks are added and removed. See fstab(5).
#
# <file system>             <mount point>  <type>  <options>  <dump>  <pass>
UUID=214D-F8FD                            /boot/efi      vfat    umask=0077 0 2
UUID=93c3d235-47b3-482c-aa36-3aabbb2a8fbe /boot          ext4    defaults,discard 0 2
UUID=97c7ace2-37a8-40aa-9771-fdf9cb2f6e54 /BACKUP        ext4    defaults,discard 0 2
UUID=defbea08-edb4-4474-926b-17812c8d5939 /              ext4    defaults,discard 0 1
UUID=05a809ef-edd1-425a-a5b4-84621973e76e /var           ext4    defaults,discard 0 2
UUID=7b57c124-3528-4889-909b-d2ff6a8d9e66 /home          ext4    defaults,discard 0 2
UUID=c67c46d0-6ad8-4153-9e93-fbc68208df48 /tmp           ext4    defaults,discard 0 2
/swapfile                                 swap           swap    defaults   0 0
tmpfs                                     /tmp           tmpfs   defaults,noatime,mode=1777 0 0

The errors from /var/log/syslog:

kernel: [  698.762590] systemd-fstab-generator[3740]: Failed to create unit file /run/systemd/generator/tmp.mount, as it already exists. Duplicate entry in /etc/fstab?
systemd[3729]: /usr/lib/systemd/system-generators/systemd-fstab-generator failed with exit status 1.

612

1 + 0

partitioning

fstab

mount

Score:3

Ubuntu

zwets

12/13/23, 9:32 PM

Your system probably has the systemd tmp.mount enabled. Check with:

systemctl status tmp.mount

If so, you don't need the /tmp mount in your /etc/fstab, as the systemd-fstab-generator will generate the entry.

+ 4

Matty

12/14/23, 11:13 PM

matthew@minestry-of-magic:~$ systemctl status tmp.mount ● tmp.mount - /tmp Loaded: loaded (/etc/fstab; generated) Active: active (mounted) since Wed 2022-12-14 18:10:30 EST; 51s ago Where: /tmp What: /dev/sda3 Docs: man:fstab(5) man:systemd-fstab-generator(8) Tasks: 0 (limit: 18592) Memory: 48.0K CPU: 4ms CGroup: /system.slice/tmp.mount Dec 14 18:10:30 minestry-of-magic systemd[1]: Mounting /tmp... Dec 14 18:10:30 minestry-of-magic systemd[1]: Mounted /tmp.

Matty

12/14/23, 11:15 PM

There are two lines in fstab for tmp: UUID=c67c46d0-6ad8-4153-9e93-fbc68208df48 /tmp ext4 defaults,discard 0 2 tmpfs /tmp tmpfs defaults,noatime,mode=1777 0 0 Should I comment out both? I segmented tmp because it is a firewall appliance (not public facing, it sits between my network and the telco modem).

zwets

12/15/23, 6:43 PM

Not sure what you mean by a "segmented tmp" but systemd will create a `tmpfs` filesystem and mount it at `/tmp`. If you are low on memory and the `/tmp` partition you created is good enough, you could equally well `systemd disable tmp.mount`.

Matty

12/16/23, 7:44 PM

I broke out the file system into individual partitions. That's what I was meaning. ah ha. ok. Thanks for the help.

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