#!/usr/bin/python

"""
    files.py -- a few file-related operations, plus a first encounter with exceptions

    Jeff Ondich, 24 October 2006

    Read, predict the output, experiment.
"""

import sys

print '=============== command-line arguments =============='
if len(sys.argv) <= 1:
    sys.stderr.write('Usage: %s filename\n' % sys.argv[0])
    sys.exit(1)

fileName = sys.argv[1]
print 'The requested file is', fileName
print

print '=============== reading from a file =============='
try:
    theFile = open(fileName)
except Exception, e:
    sys.stderr.write('Here is the error message built into the exception:\n  %s\n' % e)
    sys.exit(1)

for line in theFile:
    line = line.upper()
    print line,

theFile.close()

print

print '=============== writing to a file =============='
try:
    theFile = open('output.txt', 'w')
except Exception, e:
    sys.stderr.write('Here is the error message built into the exception:\n  %s\n' % e)
    sys.exit(1)

theFile.write('the moose frolicked\n')
theFile.write('in the meadow\n')

theFile.close()

print