The script provided at Step #2 in [0] is not linted with [shellcheck](https://github.com/koalaman/shellcheck)

4.12+

Check the script with [shellcheck](https://github.com/koalaman/shellcheck)

    1. Take [0] Step#2 script into a file
    2. Install [shellcheck](https://github.com/koalaman/shellcheck) in your environment
    3. Replacing the <device_type_glob> placeholder with a proper device filepath
    4. Run `shellcheck` against the script
    5. See results

The following is shown:

$ shellcheck script.sh 

In script.sh line 5:
/usr/sbin/blkid $device &> /dev/null
                ^-----^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean: 
/usr/sbin/blkid "$device" &> /dev/null


In script.sh line 9:
    mkfs.xfs -L var-lib-etcd -f $device &> /dev/null
                                ^-----^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean: 
    mkfs.xfs -L var-lib-etcd -f "$device" &> /dev/null

For more information:
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...

$ shellcheck script.sh
< no output >

A proposal for fix is as follows:

#!/bin/bash
set -uo pipefail

for device in <device_type_glob>; do
  /usr/sbin/blkid "${device}" &> /dev/null
  if [ $? == 2  ]; then
    echo "secondary device found ${device}"
    echo "creating filesystem for etcd mount"
    mkfs.xfs -L var-lib-etcd -f "${device}" &> /dev/null
    udevadm settle
    touch /etc/var-lib-etcd-mount
    exit
  fi
  done
echo "Couldn't find secondary block device!" >&2
exit 77

[0] https://docs.openshift.com/container-platform/4.12/scalability_and_performance/recommended-performance-scale-practices/recommended-etcd-practices.html#move-etcd-different-disk_recommended-etcd-practices