Signal

Batch file on Desktop:

%UserProfile%\Desktop\Signal.bat

@echo off
set HTTP_PROXY=http://<proxy>:<port>/
set HTTPS_PROXY=http://<proxy>:<port>/
start %LOCALAPPDATA%\Programs\signal-desktop\Signal.exe

Shortcut on Desktop with destination: C:\Windows\System32\cmd.exe /c "%UserProfile%\Desktop\Signal.bat"

/usr/share/applications/signal-desktop.desktop

[Desktop Entry]
Name=Signal
Comment=Private messaging from your desktop
Exec="/opt/Signal/signal-desktop.sh" %U
Terminal=false
Type=Application
Icon=signal-desktop
StartupWMClass=Signal
Categories=Network;
desktop entry 

/opt/Signal/signal-desktop.sh

#!/bin/sh
 
export http_proxy=http://<proxy>:<port>
export https_proxy=http://<proxy>:<port>
/opt/Signal/signal-desktop