After installing wine with a .pkg, I get the error wine: command not found when running from the terminal but the app works fine
The wine related commands are not in the path so you have to add them:

(this is for if you installed it for all users, if it's for only your user put ~/Applications instead of /Applications)

sudo ln -s /Applications/Wine\ Stable.app/Contents/Resources/wine/bin/wine /usr/local/bin/wine
sudo ln -s /Applications/Wine\ Stable.app/Contents/Resources/wine/bin/winecfg /usr/local/bin/winecfg
sudo ln -s /Applications/Wine\ Stable.app/Contents/Resources/wine/bin/msiexec /usr/local/bin/msiexec


If you installed 64-bit wine also: sudo ln -s /Applications/Wine\ Stable.app/Contents/Resources/wine/bin/wine64 /usr/local/bin/wine64

Optional:

sudo ln -s /Applications/Wine\ Stable.app/Contents/Resources/wine/bin/notepad /usr/local/bin/notepad
sudo ln -s /Applications/Wine\ Stable.app/Contents/Resources/wine/bin/regedit /usr/local/bin/regedit
sudo ln -s /Applications/Wine\ Stable.app/Contents/Resources/wine/bin/regsvr32 /usr/local/bin/regsvr32
sudo ln -s /Applications/Wine\ Stable.app/Contents/Resources/wine/bin/wineboot /usr/local/bin/wineboot
sudo ln -s /Applications/Wine\ Stable.app/Contents/Resources/wine/bin/wineconsole /usr/local/bin/wineconsole
sudo ln -s /Applications/Wine\ Stable.app/Contents/Resources/wine/bin/winedbg /usr/local/bin/winedbg
sudo ln -s /Applications/Wine\ Stable.app/Contents/Resources/wine/bin/winefile /usr/local/bin/winefile
sudo ln -s /Applications/Wine\ Stable.app/Contents/Resources/wine/bin/winepath /usr/local/bin/winepath
sudo ln -s /Applications/Wine\ Stable.app/Contents/Resources/wine/bin/wineserver /usr/local/bin/wineserver
sudo ln -s /Applications/Wine\ Stable.app/Contents/Resources/start/bin/appdb /usr/local/bin/appdb
sudo ln -s /Applications/Wine\ Stable.app/Contents/Resources/wine/bin/winehelp /usr/local/bin/winehelp