step ssh needs-renewal returns '0' if the SSH certificate needs
to be renewed based on it's remaining lifetime. Returns '1' if the SSH certificate is
within it's validity lifetime bounds and does not need to be renewed. Returns
'255' for any other error. By default, an SSH certificate "needs renewal" when it has
passed 66% (default threshold) of it's allotted lifetime. This threshold can be
adjusted using the '--expires-in' flag.
The path to an SSH certificate.
Check if the certificate expires within the given time window
using percent|duration. If using percent, the input must be followed by a "%"
character. If using duration, the input must be a sequence of decimal numbers,
each with optional fraction and a unit suffix, such as "300ms", "-1.5h" or "2h45m".
Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".
This command returns '0' if the SSH certificate needs renewal, '1' if the
SSH certificate does not need renewal, '2' if the SSH certificate file does not
exist, and '255' for any other error.
Check if an SSH certificate needs renewal using the default threshold (66%):