This python script demonstrates how to:
- Check if files exist or not
- If a file is empty or not
- How to Truncate a file
- How to insert lines to a file from the command prompt
- How to copy one file to another
#!/usr/bin/python from sys import argv import os script, file1, file2 = argv prompt = "> " #Variables that store values for if the needed files exist print "Testing if required files exist" check_filename_file = os.path.isfile('filename') check_test_file = os.path.isfile('test') #Check for if files exist is done here. if check_filename_file and check_test_file: print "All files exist. Will continue with process" print "-------------------------------------------" print "Press any key to proceed" raw_input(prompt) #Here we only ead the files and we close them. print "Will now read files %s and %s " % (file1, file2) file_1 = open(file1) file_2 = open(file2) print file_1.read() print file_2.read() file_1.close() file_2.close() #This is a nested IF. It truncates the file if it is not empty if os.stat(file2).st_size > 0: print "I will truncate the %s file " % file2 file_2 = open(file2, 'w') file_2.truncate(); file_2.close() #User is asked to enter lines that will be inserted in the second file print "Will now enter some lines in file %s " % file2 line1 = raw_input("Enter a line:") line2 = raw_input("Enter a line:") line3 = raw_input("Enter a line:") file_2 = open(file2, 'w') file_2.write(line1) file_2.write(line2) file_2.write(line3) file_2.close() else: print "No need to truncate file" #File copying. Both files are being opened (second file with write option). The first file is being read and then file_2 is instructed to be printed into file2 print "I will now copy file %s to %s" % (file1, file2) file_1 = open(file1) file_2 = open(file2, 'w') file_1_src = file_1.read() file_2_dst = file_2.write(file_1_src) file_1.close() file_2.close() else: print "Files are missing"