Awesome uses EDITOR and TERMCMD variables.

.config/awesome/rc.lua

@@ -317,7 +317,7 @@ end
 -- Note that some laptop will not work when pressing Super+Fn.
 -- Therefore we only use Fn and Mod1+Fn.
 --------------------------------------------------------------------------------
-term = "urxvt"
+term = os.getenv("TERMCMD") or "urxvt"
 termcmd = term .. " -e "
 
 globalkeys = awful.util.table.join(
@@ -329,8 +329,11 @@ globalkeys = awful.util.table.join(
    awful.key({ modkey,  }, "b",     function () awful.util.spawn(termcmd .. "calc") end),
    awful.key({ }, "XF86Calculator", function () awful.util.spawn(termcmd .. "calc") end),
 
-   -- File browser
-   awful.key({ modkey,  }, "e",     function () awful.util.spawn(termcmd .. "ranger") end),
+   -- Editor
+   awful.key({ modkey,  }, "e",     function () awful.util.spawn(os.getenv("EDITOR")) end),
+
+   -- Directory browser
+   awful.key({ modkey,  }, "d",     function () awful.util.spawn(termcmd .. "ranger") end),
    awful.key({ }, "XF86Explorer",   function () awful.util.spawn(termcmd .. "ranger") end),
    awful.key({ }, "XF86MyComputer", function () awful.util.spawn(termcmd .. "ranger") end),
 

.shell.d/main_rc

@@ -24,10 +24,6 @@ elif [ "$TERM" != "dumb" ]; then
     # export LSCOLORS="ExfxcxDxCxdxdxCxCxECEh"
 fi
 
-## This env variable is used by some programs (like ranger) to get terminal
-## executable name.
-export TERMCMD="urxvt"
-
 ## Title
 ## If this is an xterm set the title to user@host:dir
 #case "$TERM" in

.xprofile

@@ -27,3 +27,7 @@ if [ "$OSTYPE" = "linux-gnu" ] ; then
 fi
 
 [ -d "$HOME/temp" ] && export TEMP="$HOME/temp"
+
+## This env variable is used by some programs (like ranger and awesome) to get
+## terminal executable name.
+export TERMCMD="urxvt"