update-grub fails with 'Syntax error at line 194'

[Radu Marinescu]

I have followed the tutorial https://openzfs.github.io/openzfs-docs/Getting%20Started/Ubuntu/Ubuntu%2022.04%20Root%20on%20ZFS.html to install Ubuntu Server 22.04 with root on zfs. However, after installing grub-efi-amd64-signed I got a syntax error when running the update-grub command.

The culprit seems to be the following section in /etc/grub.d/10_linux_zfs (lines 861-867):
```
    if [ -n "$boot_devices" ]; then
        for device in ${boot_devices}; do
            echo "${submenu_indentation} if [ "${boot_device}" = "${device}" ]; then"
            echo "$(prepare_grub_to_access_device_cached "${device}" $(( submenu_level +1 )) )"
            echo "${submenu_indentation} fi"
        done
    else
```

In my situation, this section generated an empty 'then' section in /boot/grub/grub.cfg in each menu entry:
```
                if [ ${boot_device} = /dev/mapper/root_zdrive1 ]; then

                fi
```

Adding an `echo ":"` in /etc/grub.d/10_linux_zfs solved the problem:
```
    if [ -n "$boot_devices" ]; then
        for device in ${boot_devices}; do
            echo "${submenu_indentation} if [ "${boot_device}" = "${device}" ]; then"
            echo ":"
            echo "$(prepare_grub_to_access_device_cached "${device}" $(( submenu_level +1 )) )"
            echo "${submenu_indentation} fi"
        done
    else
```

[Environment]

Ubuntu 22.04.3 LTS

grub-efi-amd64-signed:
  Installed: 1.187.6+2.06-2ubuntu14.4
  Candidate: 1.187.6+2.06-2ubuntu14.4
  Version table:
 *** 1.187.6+2.06-2ubuntu14.4 500
        500 http://archive.ubuntu.com/ubuntu jammy-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu jammy-security/main amd64 Packages
        100 /var/lib/dpkg/status
     1.180+2.06-2ubuntu7 500
        500 http://archive.ubuntu.com/ubuntu jammy/main amd64 Packages

I hope this helps!
There is a similar bug to this, involving the same file, but that is for 19.03 and the fix and cause of the error seem to be different.

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: grub-common 2.06-2ubuntu7.2
ProcVersionSignature: Ubuntu 6.5.0-14.14~22.04.1-generic 6.5.3
Uname: Linux 6.5.0-14-generic x86_64
NonfreeKernelModules: zfs
ApportVersion: 2.20.11-0ubuntu82.5
Architecture: amd64
CasperMD5CheckResult: unknown
Date: Tue Jan 30 20:02:36 2024
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=C.UTF-8
 SHELL=/usr/bin/bash
RebootRequiredPkgs: Error: path contained symlinks.
SourcePackage: grub2
UpgradeStatus: No upgrade log present (probably fresh install)
mtime.conffile..etc.grub.d.10_linux_zfs: 2024-01-30T19:59:34.274482