Install script throws error on recent Linux kernels without cgroup v1 memory controller support

[sven-sverologos]

Environmental Info:
k3s version v1.31.5+k3s1 (56ec5dd)
go version go1.22.10

Node(s) CPU architecture, OS, and Version:
Linux leela 6.13.1-1-default #1 SMP PREEMPT_DYNAMIC Mon Feb 3 05:33:25 UTC 2025 (1918d13) x86_64 x86_64 x86_64 GNU/Linux

Cluster Configuration:
single node

Describe the bug:
Recent openSUSE Tumbleweed kernels are compiled without cgroups v1 functions (CONFIG_MEMCG_V1 not set). This causes the cgroup v1 memory controller line to be absent from /proc/cgroups. Which in turn causes the install script to fail at line 1115, i.e.

if [ -f "/proc/cgroups" ] && [ "$(grep memory /proc/cgroups | while read -r n n n enabled; do echo $enabled; done)" -eq 0 ];

Here, "$(grep memory /proc/cgroups | while read -r n n n enabled; do echo $enabled; done)" will be empty, causing the -eq test to fail.

Steps To Reproduce:

• Install K3s on recent openSUSE Tumbleweed

Expected behavior:
Install script succeeds

Actual behavior:
Install script throws error:
line 1115: [: : integer expression expected

Install does still appear to succeed though.

Additional context / logs:

[angel333]

This also applies to Alpine Linux, btw. The error looks a little different (it's BusyBox's shell) but it's the same thing.

~ # test "$(grep memory /proc/cgroups | while read -r n n n enabled; do echo $enabled; done)" -eq 0
sh: out of range