Add JANET_PATH back in.

janet.1

@@ -67,7 +67,7 @@ Quiet output. Don't print a repl prompt or expression results to stdout.
 .BR \-m\ syspath
 Set the variable module/*syspath* to the string syspath so that Janet will load system modules
 from a directory different than the default. The default is set when Janet is built, and defaults to
-/usr/local/lib/janet on Linux/Posix, and C:/Janet/Library on Windows.
+/usr/local/lib/janet on Linux/Posix, and C:/Janet/Library on Windows. This option supersedes JANET_PATH.
 
 .TP
 .BR \-c\ source\ output
@@ -86,5 +86,14 @@ or repl.
 Stop parsing command line arguments. All arguments after this one will be considered file names
 and then arguments to the script.
 
+.SH ENVIRONMENT
+
+.B JANET_PATH
+.RS
+The location to look for Janet libraries. This is the only environment variable Janet needs to
+find native and source code modules. If no JANET_PATH is set, Janet will look in
+the default location set at compile time.
+.RE
+
 .SH AUTHOR
 Written by Calvin Rose <calsrose@gmail.com>

src/mainclient/init.janet

@@ -9,6 +9,8 @@
   (var *handleopts* true)
   (var *exit-on-error* true)
 
+  (if-let [jp (os/getenv "JANET_PATH")] (set module/*syspath* jp))
+
   # Flag handlers
   (def handlers :private
     {"h" (fn [&]