3946l1.orig100664 777 330 534 7062251652 12126 0ustar ljeditorljedit3946l1 Listing 1. Help Option Handler #! /usr/local/bin/python import sys if '-h' in sys.argv or '--help' in sys.argv or '--help' in sys.argv: print ''' help.py--does nothing useful (yet) options: -h, -help, or --help-display this help Copyright (c) Jacek Artymiak, 2000 ''' sys.exit(0) else: print 'I don't recognize this option' sys.exit(0) 3946l10.orig100664 777 330 555 7062251665 12215 0ustar ljeditorljedit3946l10 Listing 10. Modifying Standard Input #! /usr/local/bin/python import sys while 1: data = sys.stdin.readline() if data != '': # do some processing of the contents of # the data variable data = '#'+data # end of data processing module sys.stdout.write(data) else: sys.stdout.flush() break 3946l11.orig100664 777 330 566 7062251702 12210 0ustar ljeditorljedit3946l11 Listing 11. Reading from Standard Input #! /usr/local/bin/python import sys while 1: data = sys.stdin.read(256) if data != '': # do some processing of the contents of # the data variable data = '#'+data # end of data processing command group sys.stdout.write(data) else: sys.stdout.flush() break 3946l12.orig100664 777 330 532 7062251717 12210 0ustar ljeditorljedit3946l12 Listing 12. Reading the Entire File at Once #! /usr/local/bin/python import sys import re data = sys.stdin.readlines() if data != '': # do some processing of the contents of the # data variable data = re.sub('A-Z]', '=', str(data)) # end of data processing module sys.stdout.write(data) else: sys.stdout.flush() 3946l13.orig100664 777 330 337 7062251745 12215 0ustar ljeditorljedit3946l13 Listing 13. Writing to Standard Input #! /usr/local/bin/python import os n = 100 try: po = os.popen('sed \'s/-/+/g\' > output', 'w') except IOError: exit(0) while n != 0: n = n-1 po.write('---\n') 3946l14.orig100664 777 330 306 7062251766 12215 0ustar ljeditorljedit3946l14 Listing 14. Reading from Pipe #! /usr/local/bin/python import os try: po = os.popen('cat /usr/doc/FAQ/txt/Linux-FAQ | pr -2', 'r') except IOError: exit(0) print po.read() 3946l15.orig100664 777 330 502 7062252174 12206 0ustar ljeditorljedit3946l15 Listing 15. Writing to System Log #! /usr/local/bin/python import syslog syslog.syslog('syslog junkie: the script has just got woken up') # some code for a in ['a', 'b', 'c']: b = 'syslog junkie: I found letter '+a syslog.syslog(b) syslog.syslog('syslog junkie: the script goes to sleep now, bye, bye!') 3946l16.orig100664 777 330 540 7062252210 12200 0ustar ljeditorljedit3946l16 Listing 16. Output Listing Jan 20 00:35:28 localhost python: syslog junkie script has just got woken up Jan 20 00:35:28 localhost python: I found letter a Jan 20 00:35:28 localhost python: I found letter b Jan 20 00:35:28 localhost python: I found letter c Jan 20 00:35:28 localhost python: syslog junkie script goes to sleep now, bye, bye! 3946l17.orig100664 777 330 544 7062252235 12214 0ustar ljeditorljedit3946l17 Listing 17. Modifying an Environment Variable #! /usr/local/bin/python import os if os.environ['USER']: print 'USER was '+os.environ['USER'] old_user = os.environ['USER'] os.environ['USER'] = 'Jacek'' print 'USER is now '+os.environ['USER'] os.environ['USER'] = old_user print 'USER is '+os.environ['USER']+' back again.' 3946l2.orig100664 777 330 3344 7062252274 12152 0ustar ljeditorljedit3946l2 Listing 2. Option Handler, options.py #! /usr/local/bin/python import sys, getopt, string def help_message(): print '''options.py -- uses getopt to recognize options Options: -h -- displays this help message -a -- expects an argument --file= -- expects an argument --view -- doesn't necessarily expect an argument --version -- displays Python version''' sys.exit(0) try: options, xarguments = getopt.getopt(sys.argv[1:], 'ha', ['file=', '--view', 'version']) except getopt.error: print 'Error: You tried to use an unknown option or the argument for an option that requires it was missing. Try `options.py -h\' for more information.' sys.exit(0) for a in options[:]: if a[0] == '-h': help_message() for a in options[:]: if a[0] == '-a' and a[1] != '': print a[0]+' = '+a[1] options.remove(a) break elif a[0] == '-a' and a[1] == '': print '-a expects an argument' sys.exit(0) for a in options[:]: if a[0] == '--file' and a[1] != '': print a[0]+' = '+a[1] options.remove(a) break elif a[0] == '--file' and a[1] == '': print '--file expects an argument' sys.exit(0) for a in options[:]: if a[0] == '--view' and a[1] != '': print a[0]+' = '+a[1] options.remove(a) break elif a[0] == '--view' and a[1] == '': print '--view doesn\'t necessarily expects an argument...' options.remove(a) sys.exit(0) for a in options[:]: if a[0] == '--version': print 'options version 0.0.001' sys.exit(0) for a in options[:]: if a[0] == '--python-version': print 'Python '+sys.version sys.exit(0) 3946l3.orig100664 777 330 415 7062252311 12117 0ustar ljeditorljedit3946l3 Listing 3. Signal Traps #! /usr/local/bin/python import signal import sys def signal_handler(signal, frame): print 'You pressed Ctrl+C!' sys.exit(0) signal.signal(signal.SIGINT, signal_handler) print 'Press Ctrl+C' while 1: continue 3946l4.orig100664 777 330 302 7062252324 12117 0ustar ljeditorljedit3946l4 Listing 4. Ignoring Signal #! /usr/local/bin/python import signal signal.signal(signal.SIGINT, signal.SIG_IGN) print 'Your script can\'t be stopped with Ctrl+C' while 1: continue 3946l5.orig100664 777 330 443 7062252340 12124 0ustar ljeditorljedit3946l5 Listing 5. Using Alarm Signal #! /usr/local/bin/python import signal import sys def alarm_handler(signal, frame): print 'BOOM!' sys.exit(0) signal.signal(signal.SIGALRM, alarm_handler) signal.alarm(5) # generate SIGALRM after 5 secs n = 0 while 1: print n n = n+1 3946l6.orig100664 777 330 313 7062252360 12123 0ustar ljeditorljedit3946l6 Listing 6. Opening a Read File #! /usr/local/bin/python import sys try: fi = open('sample_+_file', 'r') except IOError: print 'Can\'t open file for reading.' sys.exit(0) 3946l7.orig100664 777 330 326 7062252374 12135 0ustar ljeditorljedit3946l7 Listing 7. Opening a Write File #! /usr/local/bin/python import os import sys try: fi = open('sample_+_file', 'w') except IOError: print 'Can\'t open file for writing.' sys.exit(0) 3946l8.orig100664 777 330 631 7062252413 12127 0ustar ljeditorljedit3946l8 Listing 8. Creating Temporary Files #! /usr/local/bin/python import os import tempfile import sys try: t_path = tempfile.mktemp() ttt = os.open(t_path, os.O_CREAT | os.O_RDWR) # O_RDWR allows read & write except IOError: print 'Error: Couldn\'t create temp file.' sys.exit(0) # always close and remove the temp file # before you exit from script os.close(ttt) os.remove(t_path) 3946l9.orig100664 777 330 1500 7062252455 12152 0ustar ljeditorljedit3946l9 Listing 9. Removing Temporary Files #! /usr/local/bin/python import os import tempfile import sys import signal t_path = '' t_file = None def cleanup(signal, frame): if t_path != '' and t_file != None: print 'Cleaning up temporary files ...' os.close(t_file) os.remove(t_path) print 'Done!' sys.exit(0) else: sys.exit(0) signal.signal(signal.SIGHUP, cleanup) signal.signal(signal.SIGINT, cleanup) signal.signal(signal.SIGQUIT, cleanup) signal.signal(signal.SIGTERM, cleanup) try: t_path = tempfile.mktemp() t_file = os.open(t_path, os.O_CREAT | os.O_RDWR) except IOError: print 'Error: Couldn\'t create temp file.' sys.exit(0) # INSERT YOUR OWN CODE HERE # always close and remove the temp file # before you exit from script cleanup(t_path, t_file)