Add subproctools.py.

voussoirkit/subproctools.py

@@ -0,0 +1,32 @@
+import os
+
+def quote(arg):
+    if os.name == 'nt':
+        # If the command contains comma, semicolon, or equals, only the left
+        # half is considered the command and the rest is considered the first
+        # argument. If these characters are in other arguments they are
+        # sometimes parsed as separate by builtin commands like del, but not
+        # separate for external applications.
+        # Ampersand, pipe, and caret are process flow and special escape.
+        # Quotes inside quotes must be doubled up.
+        if arg == '' or any((c.isspace() or c in arg) for c in [',', ';', '=', '&', '|', '^', '"']):
+            arg = arg.replace('"', '""')
+            arg = f'"{arg}"'
+        return arg
+    else:
+        # Semicolon is command delimiter.
+        # Equals assigns shell variables.
+        # Quotes inside quotes must be escaped with backslash.
+        if arg == '' or any((c.isspace() or c in arg) for c in [' ', ';', '=', '&', '|']):
+            arg = arg.replace("'", "\\'")
+            arg = f"'{arg}'"
+        return arg
+
+def format_command(command):
+    cmd = [quote(x) for x in command]
+    cmd = ' '.join(cmd)
+    cmd = cmd.strip()
+    return cmd
+
+def print_command(command, prefix=''):
+    print(prefix + format_command(command))