读取文件并复制到标准输出。

Question

I'm trying to write a python program that will read input and copy it to standard output (with no alterations). I've been told that it needs to operate as a Python version of the Unix cat function. If a file cannot be opened, an error message needs to be printed, and then the program needs to continue processing any additional files. I am a complete beginner, and have tried my best to scrape something together with my limited knowledge. Here is what I have so far:

from sys import argv, stdout, stdin, stderr

if len(argv) == 1:

    try:
        stdout.write(raw_input(' ') + '\n')
    except:
        stderr.write ('sorry' + '\n')
        quit()

else:

    for filename in argv[1:]:
        try:
            filehandle + open(filename)
        except IOError:
            stderr.write('Sorry, could not open', filename + '\n')
            continue

        f = filehandle.read()

        stdout.write(f)

I am not quite sure where to go from here.. does anyone have any advice/am I on the right track even a little bit? Please and thank you!

Answer 1

This function will copy the specified file to the console line by line (in case you later on decide to give it the ability to use the -n command line option of cat)

def catfile(fn):
  with open(fn) as f:
    for line in f:
      print line,

It can be called with the filename once you have established the file exists.