putenv and setenv are both supposed to be POSIX compliant. If you have code with putenv in it, and the code works well, leave it alone. If you are developing new code you may want to consider setenv. Look at the glibc source code if you want to see an example of an implementation of setenv (stdlib/setenv.c) or putenv (stdlib/putenv.c).

Feb 24, 2017 · The putenv function sets the value of an environment variable. According to the manual, putenv returns true on success, false on failure. However, I'm finding that the putenv function sometimes returns true without updating the environment variable for the current session.

Jan 20, 2019 · While std::getenv is part of the C++ standard (and the C standard as well, but in the future pick one language, the one you really program in which in your case is C++), the putenv function isn't. As you can see from the linked POSIX reference for …

May 10, 2017 · Note: Calling putenv() directly does not change os.environ, so it’s better to modify os.environ. For unsetenv there is a similar warning: however, calls to unsetenv() don’t update os.environ, so it is actually preferable to delete items of os.environ.

Feb 9, 2019 · Originally, I had used the putenv function since it was mentioned on another SO answer, ...

This function makes copies of the strings pointed to by name and value (by contrast with putenv(3)). The unsetenv() function deletes the variable name from the environment. If name does not exist in the environment, then the function succeeds, and the environment is unchanged.

Aug 5, 2010 · putenv(char *string) is dangerous for the reason that all it does is simply append the address of your key-value pair string to the environ array. Therefore, if we subsequently modify the bytes pointed to by string , the change will affect the process environment.

Apr 17, 2015 · putenv("varname=".getenv("varname")); then it becomes available to the extension's code. The question: why is that reinstantiation necessary? How is the core php environment distinct from the "standard" (stdlib) environment? This occurs with: PHP Version 5.3.10-1ubuntu3.17 in Ubuntu 12.04, as an apache module. When run from the command line ...

Jan 24, 2017 · Laravel .env file values are read by Laravel at the application bootstrap time and stored in the PHP $_ENV global array under the respective keys.

Mar 20, 2021 · Don't use windows, but maybe you could use system() to set environment variables through the cmd? <EDIT> I just checked and apparently this is the command to set environment variables.