Scripts

Ricardo

Mar 28, 2021 • 3 min read

General

How to find and delete duplicate files within the same directory?

I want to find duplicate files, within a directory, and then delete all but one, to reclaim space. How do I achieve this using a shell script? For example: pwdfolder Files in it are: log.bkplog

Unix & Linux Stack ExchangeSu_scriptingbee

How to update WSL DNS settings when using a VPN

Problem: When connecting with a VPN, WSL's gateway setting does NOT get updated. "apt update" will stop working, for example. These instructions depend on your VPN utility executing a script as soon as the link is up.

In WSL edit /etc/wsl.conf with the following, then restart it

[network]
generateResolvConf = false

Install BurntToast from Powershell:

Install-Module BurntToast

In WSL create setdns

echo "nameserver $1" >/etc/resolv.conf
Then make it executable
chmod u+x setdns

In windows create setdns.ps1

# Get VPN Gateway
$gw = Get-WmiObject -Class Win32_IP4RouteTable |
where { $.destination -eq '0.0.0.0' -and $.mask -eq '128.0.0.0'} |
Sort-Object metric1 | select nexthop -ExpandProperty nexthop
# Run script that sets resolv.conf
wsl ~/setdns $gw
New-BurntToastNotification -Text "Set WSL Gateway to $gw"
exit

In the VPN application, find the "VPN Up" event handler and set it to

powershell.exe -noexit "& ""C:\PATH\setdns.ps1"""

Where PATH is the directory containing setdns.ps1

Note: Typically the VPN app will display the current gateway being used. In step 4, if no gateway was found (or it found your local gateway instead of the VPN's gateway), the mask may need to be '0.0.0.0' instead of '128.0.0.0', depending on your VPN service. You can double check by looking at the output of the following command (in Windows), and match to your current gateway, e.g. 1.2.3.4

netstat -rn | find "1.2.3.4"

Look at the line where the gateway is the third column - the mask is in the second column.

Now every time you connect, the gateway will be updated in WSL and a toast will display with the new value.