Nirjan,
On 4/26/21 14:19, Niranjan Rao wrote:
On 4/14/21 5:29 AM, Rony G. Flatscher (Apache) wrote:
A JVM
AFAIK would not honor changes to the environment after it got started
A serious question. Apologies for selective selection from the response.
Are there any operating systems where change in environment is
automatically reflected in child process?
That would be a fairly chaotic system. I don't know of any that do this
kind of thing.
My understanding was, processes always inherit parent environment and
have no way of knowing what changed.
A copy of the parent environment is made into the child process, which
diverges from that point forward.
The reason JVMs "would not honor changes to the environment after it got
started" is because most components that configure based upon envirnment
variables (or system properties for that matter) only check them when
first initialized. If you change an environment variable in a process
(whether from the inside or the outside), it only changes behavior of
the variable's value is directly-checked periodically instead of "just
once at startup."
If you managed to spawn a process with different parent based on your
operating system, then you might see new values, but most of the
spawn/exec calls (regardless of language of implmentation) inherit the
exact same environment variables. Some calls do allow you to setup the
environment variables for child process but struggling to figure out
where grandparent process informed parent about environment change which
can be sent to grandchild.
I don't believe any of that can happen, at least not in theway you
describe. Of course, IPC does exist and you *can* send data between
processes, so a grantparent process could theoretically tell the
grandchild process "hey you should set FOO=bar" but the grandchild
process would have to support that kind of IPC and agree to make the
change. The gp process can't just reach-in and change the environment.
-chris
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