When running the `screen` command in a WSL (Windows Subsystem for Linux) Debian-based environment, you may get this error:
```
$ screen -ls
Cannot make directory '/run/screen': Permission denied
```

Or even this:
```
$ screen -ls
Cannot make directory '/run/screen': File exists
```

You can safely remove that directory if you don't need it:
```shell
sudo rm /run/screen
```

Then set the `SCREENDIR` environment variable as follows:
```shell
export SCREENDIR=$HOME/screens
```

And it should work now:
```
$ screen -ls
No Sockets found in /home/john/screens.
```

To make the `SCREENDIR` environment variable permanent, add it to your configuration file:
```shell
nano ~/.bashrc
```

Just put this at the end of the file:
```shell
# Set the GNU Screen environment variable.
export SCREENDIR=$HOME/screens
```