Passing and updating an environment variable constantly - linux

I need a way to constantly update a environment variable from a script. I need to use that environment variable in another program almost real time.
What I have is this code:
# !bin/bash
while :
do
AMA="$(cut -c 1-13 text.txt)"
source directory/this_script
done
I am getting the right information from my file when running cut this way. I just need to get this variable permanently updating if possible. Also a way to even get it to the environment.
Slackware Linux

Related

Windows Environment Variables - Troubling accessing updated environment variables in program

I have wrote an initialization script that sets user environment variables which are keys that have been hashed and encrypted...Once the keys have been created the key encryption exe is no longer required. I want to launch the main application and remove the init file containing the hashing and key encryption functions.
I am not having any trouble with any of the above...Everything works as should when independent of each other. The problem is that in order for the main application to have access to the newly created environment variables I need the init script to completely exit...
Everything I have tried, Popen with flags, os.system() and others have still left me in a situation where the parent process ends and the main application launches, however, the environment variables have not updated...I close and relaunch main.py and...boom the program sees the updated variables and all is fine.
All I want is the init script to run, spawn a new process that is not linked at all with init.py and then exit so it can be removed. I thought this would be simple but after many hours of head scratching and trying numerous things, I am still no closer.
If I have to I will simply bundle it as two separate .exe files but I wanted it to be a one click install type thing.
I am running windows 10 and this can be platform specific.
Links looked at:
How to stop/terminate a python script from running?
Using a Python subprocess call to invoke a Python script
Starting a separate process
https://docs.python.org/2/library/subprocess.html
Python: Howto launch a full process not a child process and retrieve the PID
And more...
Current closest result
p = Popen(["python","UserInterface.py"], stdin=PIPE, stdout=PIPE, stderr=PIPE,
creationflags=DETACHED_PROCESS | CREATE_NEW_PROCESS_GROUP)
Create an environment block, set the environment variable using SetEnvironmentVariable, and use CreateProcess to specify this environment block for the created process.
MSDN DOC:
To specify a different environment for a process, create a new
environment block and pass the pointer to it as a parameter to the
CreateProcess function.
...
To programmatically add or modify system environment variables, add
them to the
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session
Manager\Environment registry key, then broadcast a WM_SETTINGCHANGE
message with lParam set to the string "Environment". This allows
applications, such as the shell, to pick up your updates.

How to query a node.js instance what options/flags were set?

I'm running a node app inside a container. A number of flags and options are passed to node when it is running and I want to figure out which options made it finally to the script.
I have found the documentation on setting these flags but I can't find anything to get them. I can query the environment variables, but what if I have made a typo and it didn't set anything?
So how can I output somehow the flags an actual node instance is running with?
What non-direct methods I have tried so far
outputting environment variables with console.dir(process.env): the problem it does not show flags passed from command line
Trying to pass a wrong flag: for example passing this NODE_OPTIONS=--max-hold-spice-size=123 will make node to fail, so at least you know that you can pass flags to node
You can access every environment variable visible to node instance using:
console.log(process.env)

Is there a way to use a global variable for the whole npm project?

I need to use a variable between node modules folder and src folder.Is there a way to use a variable to be used within the whole project?
Thanks.
Typically this is done with process environment variables. Any project can look for a common environment variable and handle that case accordingly, as well as the node modules of said project. As long as they agree on the name, they all share the same environment. Have a good default, don't force people to set this environment variable.
The environment can be set using an environment file (do not check this into source control!), on your container or cloud configuration, or even right on the command line itself.
TLOG=info npm test
That is an example that I use frequently. My project runs logging for the test cases only at alert level - there are a lot of tests so it makes the output less verbose. However, sometimes while developing I want to see all the logs, so my project is looking for an environment variable TLOG (short for "test logging") and I can set it just for that run! Also no code change is needed, which is nicer than JavaScript variables that need to be set back to original values, forget to be turned off, etc.

Puppet missing Facter environment variables

Any environment variable prefixed with "FACTER_" is automatically added to the facter collection. I've successfully added a "FACTER_" environment variable it is indeed showing up in the facter -p list, so it should be able to be used by puppet...
The problem, though, is in my .pp file the variable name that should be set to the FACTER_ value is empty (or non existant)
Is there something else I need to do to get FACTER_ variables into puppet variables?
Cheers
You are most likely setting up the system so that the FACTER_ variables are available in interactive shells. This is not sensible if you want your background agent to respect them.
I can see two direct approaches:
Modify your initscript or its configuration to set the appropriate environment variables.
Forego the approach entirely and use /etc/facter/facts.d instead.
I would advise towards the latter.

Why forever can't see environment variable?

I had a problem for accessing environment variable using forever.
Thanks to this post, I have a workaround making env vrariable accessible but I'm still wondering why I have to add them all the time :
MY_VARIABLE=SOMETHING forever start my_script.js
because I've previously done an :
export MY_VARIABLE=SOMETHING
Then opened a new terminal but still no luck ...
I would like to set my variable once and not have to write it down each time I'm managing my script ...
Thanks for people who will take time to make me less an idiot and satisfy my curiosity ...
export setting tightly on the current bash or session effectively.It exists in memory.

Resources