multimov

#!/usr/bin/python3
# Copyright (C) 2011-2013 Christian Siefkes.
#
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# copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
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# persons to whom the Software is furnished to do so, subject to the
# following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
# NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
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"""
multimov - move a specified number of files with the same extension at once
"""


from os import extsep, getcwd, listdir, makedirs
from os.path import isdir
from shutil import move
from sys import argv, exit, stderr


def multimov(filecount, extension, targetdir):
    """
    Moves up to *filecount* files with the specified *extension*
    (case-insensitive) from the current directory into the *targetdir*.
    """
    # Add dot if needed
    if not extension.startswith(extsep):
        extension = extsep + extension
    lowerextension = extension.lower()

    # Filter matching files and sort them alphabetically
    allfiles = listdir(getcwd())
    matchingfiles =\
        [file for file in allfiles if file.lower().endswith(lowerextension)]
    matchingfiles.sort()
    actualcount = min(filecount, len(matchingfiles))
    if actualcount <= 0:
        _exiterror("No files to move")

    # Try to create targetdir if it's not an existing directory
    if not isdir(targetdir):
        try:
            makedirs(targetdir)
        except OSError as e:
            _exiterror("Can't create target directory {}: {}".format(
                targetdir, e))

    # Move first actualcount files into targetdir
    for i in range(actualcount):
        move(matchingfiles[i], targetdir)


def _exiterror(msg):
    """Print an error message and exit."""
    fullmsg =\
"""Error: {}
Usage: multimov FILECOUNT EXTENSION TARGETDIR: move the specified number
       of files with the given extension to the target directory.""".format(
          msg)
    print(fullmsg, file=stderr)
    exit(1)


# main block
if __name__ == "__main__":
    # Read 3 arguments: filecount, extension, targetdir
    if len(argv) == 4:
        rawfilecount = argv[1]
        extension = argv[2]
        targetdir = argv[3]

        try:
            filecount = int(rawfilecount)
        except ValueError:
            _exiterror("FILECOUNT is not a number: {}".format(rawfilecount))

        multimov(filecount, extension, targetdir)
    else:
        _exiterror("{} argument(s) instead of 3".format(len(argv) -1))