upysh: Minimalistic file shell using native Python syntax.

E.g. cat("file") is equivalent of Unix shell's 'cat file'. With some tricks
though makes pwd and ls work without parens.

upysh/upysh.py

@@ -0,0 +1,49 @@
+import sys
+import os
+
+class LS:
+
+    def __repr__(self):
+        l = os.listdir()
+        l.sort()
+        return "\n".join(l)
+
+    def __call__(self, path="."):
+        l = os.listdir(path)
+        l.sort()
+        for f in l:
+            print(f)
+
+class PWD:
+
+    def __repr__(self):
+        return os.getcwd()
+
+    def __call__(self):
+        return self.__repr__()
+
+pwd = PWD()
+ls = LS()
+
+def cd(path):
+    os.chdir(path)
+
+def head(f, n=10):
+    with open(f) as f:
+        for i in range(n):
+            l = f.readline()
+            if not l: break
+            sys.stdout.write(l)
+
+def cat(f):
+    head(f, 1 << 30)
+
+def help():
+    print("""
+This is 'upysh' help, for builtin Python help run:
+import builtins
+builtins.help()
+
+upysh commands:
+pwd, cd("new_dir"), ls, ls(...), head(...), cat(...)
+""")