What does the command mount -a do?

The `noauto` option in `/etc/fstab` explicitly prevents a file system from being mounted by `mount -a` or during the boot process.

While `mount` without arguments shows mounted filesystems, `mount -a` actively attempts to *mount* filesystems, not just display them.

`mount` is a command for managing file system mounts, not for editing configuration files; an editor like `vi` or `nano` would be used for modifying `/etc/fstab`.

The `mount -a` command processes the `/etc/fstab` file, which lists file systems to be mounted automatically at boot or upon explicit command invocation. It specifically mounts file systems that have the `auto` option, indicating they should be mounted automatically.

`mount -a` respects the `noauto` option in `/etc/fstab` and will not mount those file systems, so it does not mount all listed file systems regardless of their options.