Better explore, and document it.

doc/explore.md

@@ -0,0 +1,16 @@
+npm-explore(1) -- Browse an installed package
+=============================================
+
+## SYNOPSIS
+
+    npm explore <name>[@<version>] [<cmd>]
+
+## DESCRIPTION
+
+Spawn a subshell in the directory of the installed package specified.
+
+If a command is specified, then it is run in the subshell, which then
+immediately terminates.
+
+Note that the package is *not* automatically rebuilt afterwards, so be
+sure to use `npm rebuild <pkg>` if you make any changes.

lib/explore.js

@@ -2,7 +2,7 @@
 // open a subshell to the package folder.
 
 module.exports = explore
-explore.usage = "npm explore <pkg>[@<version>]"
+explore.usage = "npm explore <pkg>[@<version>] [<cmd>]"
 explore.completion = function (args, index, cb) {
   var installedPkgs = require("./utils/completion/installed-packages")
   installedPkgs(args, index, true, false, cb)
@@ -13,12 +13,18 @@ var npm = require("../npm")
   , path = require("path")
 
 function explore (args, cb) {
-  var p = args[0]
-  if (args.length !== 1 || !p) return cb(edit.usage)
+  if (args.length < 1 || !args[0]) return cb(explore.usage)
+  var p = args.shift()
+  args = args.join(" ").trim()
+  if (args) args = ["-c", args]
+  else args = []
   p = p.split("@")
   var editor = npm.config.get("editor")
     , n = p.shift()
     , v = p.join("@") || "active"
-  console.log("Type 'exit' or ^D when finished")
-  exec("bash", [], null, true, path.join(npm.dir, n, v, "package"), cb)
+    , cwd = path.join(npm.dir, n, v, "package")
+  if (!args.length) console.log(
+    "\nExploring "+cwd+"\n"+
+    "Type 'exit' or ^D when finished\n")
+  exec("bash", args, null, true, cwd, cb)
 }