In Python, how to get an environment variable?
In Python, you may use this piece of code to get an environment variable:
os.environ.get('ENV_MIGHT_EXIST')
or this piece of code:
os.getenv('ENV_MIGHT_EXIST')
It will return None if the environment variable is not present.
Reference and for more ways, please check https://www.systutorials.com/dtivl/13/how-to-get-an-environment-variable?show=80#answer-80 .
Fedora Linux starts to use systemd to manage system service. The /etc/inittab is no longer used by systemd. The old method of editing /etc/inittab to change system runlevel does not work anymore. This post introduces a “manual” way to change the boot levels. For the general method, please check https://www.systutorials.com/change-systemd-boot-target-linux/. systemd uses ‘targets’ instead of…
How to test whether a user account, say linuxuser, already exist on Linux? You may make use of id which tries to get user IDs. The Bash code snippet is as follows. user=hello id -u $user >/dev/null 2>&1 if [ “$?” == “0” ]; then echo “user $user already exist.” else echo “user $user doesn’t…
How to use iptables to limit rates new SSH incoming connections from each IP on Linux? For example, at most 6 SSH connection attempts every 60 seconds. You may use these rules (skip the first one, if you have set the basic rules): for tables in iptables ip6tables ; do # Allow established inbound connections…
From the opening window by JavaScript window.open(), we can pass info to the opened by hash. But how to pass results back from the opened window to the openning window in JavaScript? Assume in the opener window, a JavaScript variable is defined like var exchangeVar = ”; In the opened window, you can update the…
How to install IE under wine on Linux? Just need it for some testing. Do not want to reboot to Windows. We ever had ies4linux. But it is obsoleted now. linie is the latest effort. But there are issues and you may need to fix some problems by yourself. Installing a Windows VM may be…
The world of technology has evolved drastically over the last few decades. Almost every aspect of our lives is dominated by technology. At the heart of technology lies computer programming. Computer programming is what dictates the success of the technology. I mean think about it, your smartphone, PC, ETC they all rely on programming. This…