Beginners Guide to Automounting File Systems With autofs and systemd

Updated: 30 September 2026 · Applies to: autofs 5.1 and systemd automount on AlmaLinux and Rocky Linux 9 and 10, RHEL 9 and 10, Ubuntu 24.04 and 26.04, Debian 13

Automounting mounts a file system only when someone accesses its folder, and unmounts it again after a period of inactivity. This is useful for network shares (NFS, SMB) that are not always needed, or that may not be reachable at boot. There are two ways: the autofs service, which is flexible and supports many shares from one map, and systemd's automount option in /etc/fstab, which needs no extra software. We checked both on AlmaLinux 9 (autofs 5.1.7).

Option 1: autofs

1. Install it (plus the NFS client tools for NFS shares):

   dnf install autofs nfs-utils          # AlmaLinux, Rocky Linux, RHEL
   apt install autofs nfs-common         # Ubuntu, Debian

2. Create a master map entry in /etc/auto.master.d/nfs.autofs. It tells autofs to manage /mnt/nfs with the map /etc/auto.nfs and to unmount after 5 minutes without use:

   /mnt/nfs  /etc/auto.nfs  --timeout=300

3. Create the map /etc/auto.nfs. Each line is a key (the folder name under /mnt/nfs), mount options and the location:

   data     -fstype=nfs4,rw   nfs.example.com:/export/data
   backups  -fstype=nfs4,ro   nfs.example.com:/export/backups

4. Start autofs and test:

   systemctl enable --now autofs
   ls /mnt/nfs/data
   mount | grep /mnt/nfs

   The share is mounted the moment you access /mnt/nfs/data. Note that ls /mnt/nfs itself may look empty until a share is accessed.

automount -m prints all maps as autofs reads them, which helps to find mistakes. The line +dir:/etc/auto.master.d in /etc/auto.master is what loads your file; it is there by default.

Option 2: systemd automount in /etc/fstab

For one or two shares, add the automount options to a normal /etc/fstab line:

nfs.example.com:/export/data  /mnt/data  nfs4  rw,noauto,x-systemd.automount,x-systemd.idle-timeout=300,_netdev  0 0

systemctl daemon-reload
systemctl restart remote-fs.target
ls /mnt/data

x-systemd.automount creates an automount point, x-systemd.idle-timeout unmounts after 5 minutes without use, and noauto prevents mounting at boot. The boot no longer waits for the share.

Which one to use

• Few, fixed shares: systemd automount, no extra service.
• Many shares, home folders for many users, or maps shared through LDAP: autofs.

Official documentation: auto.master manual and systemd.automount manual.