What is the all_proxy environment variable used for?
Solution 1:
I found a post in a mailing list which says:
We already export http,ftp,https proxy environment variables. Some environments, GNOME for instance, place the socks proxy in ALL_PROXY and all_proxy. Export it as well.
Here is the post http://lists.o-hand.com/poky/2431.html
So it's for the SOCKS proxy in gnome.