### Function

# GLib setenv

since: 2.4

#### Declaration

    gboolean
    g_setenv (
      const gchar* variable,
      const gchar* value,
      gboolean overwrite
    )

#### Description

Sets an environment variable. On UNIX, both the variable’s name and value can be arbitrary byte strings, except that the variable’s name cannot contain ‘=’. On Windows, they should be in UTF-8.

Note that on some systems, when variables are overwritten, the memory used for the previous variables and its value isn’t reclaimed.

You should be mindful of the fact that environment variable handling in UNIX is not thread-safe, and your program may crash if one thread calls `g_setenv()` while another thread is calling getenv(). (And note that many functions, such as gettext(), call `getenv()` internally.) This function is only safe to use at the very start of your program, before creating any other threads (or creating objects that create worker threads of their own).

If you need to set up the environment for a child process, you can use `g_get_environ()` to get an environment array, modify that with `g_environ_setenv()` and g_environ_unsetenv(), and then pass that array directly to execvpe(), g_spawn_async(), or the like.

Available since: 2.4

#### Parameters

`variable`

  Type: `const gchar*`

  The environment variable to set, must not contain ‘=’.

  The data is owned by the caller of the function.
  The value is a file system path, using the OS encoding.

`value`

  Type: `const gchar*`

  The value for to set the variable to.

  The data is owned by the caller of the function.
  The value is a file system path, using the OS encoding.

`overwrite`

  Type: `gboolean`

  Whether to change the variable if it already exists.

#### Return value

Type: `gboolean`

`FALSE` if the environment variable couldn’t be set.