[file_utils] unln: handle options with argparse

Remove the now useless error() function.
Add options --verbose and --sync.

file_utils/unln.py

@@ -29,10 +29,10 @@
 # inodes by doing the equivalent of (cp -p file tmp && mv tmp file).
 #
 # TODO:
-# - Option verbose
 # - Option to follow symlinks
 
 
+import argparse
 import sys
 import os
 import tempfile
@@ -45,7 +45,7 @@ def verbose(*message, **args):
     This function is a simple wrapper around print(), and you can use any
     keyword argument you would use with print().
     """
-    if options["verbose"]:
+    if options.verbose:
         print(*message, **args)
 
 def warn(*message, prefix="Warning!", **args):
@@ -60,46 +60,33 @@ def warn(*message, prefix="Warning!", **args):
     sys.stdout.flush()
     print(prefix, *message, file=sys.stderr, **args)
 
-def error(error_code, *message, **args):
-    """Prints the message on the error output and exits with 'error_code'.
-
-    This function is a simple wrapper around warn(), and you can use any
-    keyword argument you would use with warn() or print().
-    """
-    warn(*message, prefix="", **args)
-    sys.exit(error_code)
-
 def quote(string):
     """ Quotes a string. """
     return "``{}´´".format(string)
 
 
-# Default options
-options = {
-    "verbose": True
-    }
+# Parse command-line arguments
+arg_parser = argparse.ArgumentParser(
+    description="Separate a file name from its other hard links",
+    epilog="For more information about this program, see the README file \
+provided with the distribution.")
+arg_parser.add_argument("-s", "--sync", action="store_true",
+                        help="sync files after a copy to be more fail safe \
+(requires Python 3.3 or above, will be ignored with lower versions)")
+arg_parser.add_argument("-v", "--verbose", action="store_true",
+                        help="increase output verbosity")
+arg_parser.add_argument("filenames", metavar="file", nargs="+",
+                        help="file name to work on")
+options = arg_parser.parse_args()
 
-# Name of this program
-progname = os.path.basename(sys.argv[0])
-
-# Short usage string
-usage_string = "Usage:\n\t{} <file1> [file2 ...]".format(progname)
-
-# Error codes
-ERR_BAD_USAGE = 1
 
 # List of filenames that were supposed to be worked on but could not because of
 # an error
 error_filenames = []
 
 
-# Check command-line arguments
-if len(sys.argv) < 2:
-    error(ERR_BAD_USAGE, usage_string)
-
-
 # Main loop
-for filename in sys.argv[1:]:
+for filename in options.filenames:
     # Exists?
     if not os.path.exists(filename):
         warn(quote(filename), "does not exist, ignoring.")
@@ -124,7 +111,8 @@ for filename in sys.argv[1:]:
     verbose(quote(filename), "has", nlinks, "hard links, proceeding", end="... ")
 
     # Reserve a temporary file name
-    dirname = os.path.dirname(filename)
+    dirname = os.path.dirname(filename) # filename's directory
+    progname = os.path.basename(__file__) # name of this program
     try:
         handle, tmpfilename = tempfile.mkstemp(
             prefix="{}-".format(filename),
@@ -150,7 +138,7 @@ for filename in sys.argv[1:]:
         continue
 
     # Sync (if we are running Python >= 3.3)
-    if sys.version_info.minor >= 3:
+    if options.sync and sys.version_info.minor >= 3:
         verbose("Syncing", end="... ")
         os.sync()