How to correctly set/get environment variables

robcont_

Hi all. For my project I have two applications running: a "system app" and a "user app". To do its job, the system app must to know what user app is currently running. I thought about setting up 2 environment variables, named CURR_APP_NAME and CURR_APP_PID, defined in /etc/profile. Now, the desired is to set them at runtime from the user app, and get their value from the system app.

# /etc/profile
export CURR_APP_NAME=""    
export CURR_APP_PID=""

# user app - main.cpp
QGuiApplication app(argc, argv);
qputenv("CURR_APP_NAME", QByteArray(app.applicationName().toUtf8()));    
qputenv("CURR_APP_PID",  QByteArray(app.applicationPid().toUtf8()));

# system app - main.cpp
[...  when a certain signal is triggered ]
QString name = qgetenv("CURR_APP_NAME");    
QString pid  = qgetenv("CURR_APP_PID");

The problem is that the value of my environment variables is not set "globally", the system app always read an empty value.
What am I doing wrong?

sierdzio

Environment is separate for each user. So when you set the env var in your user app, it does not set that value for root. This is not a bug or anything - rather a (among others) security feature.

You can save your PID to a file, then system app will be able to read that file from the same path.

Or use some proper IPC communication techniques, like DBus, QtRemoteObjects, QLocalSocket etc.

robcont_

@sierdzio
Thanks for your help. I think I'll use QDbus to do my job.