How do I iterate over all lines of files passed on the command line?

Question

I usually do this in Perl:

whatever.pl

while(<>) {
    #do whatever;
}

then cat foo.txt | whatever.pl

Now, I want to do this in Python. I tried sys.stdin but I have no idea how to do as I have done in Perl. How can I read the input?

Answer 1

Try this:

import fileinput
for line in fileinput.input():
    process(line)

Answer 2

import sys
def main():
    for line in sys.stdin:
        print line
if __name__=='__main__':
    sys.exit(main())

Answer 3

Something like this:

import sys

for line in sys.stdin:
    # whatever

Answer 4

import sys

for line in sys.stdin:
    # do stuff w/line

Answer 5

I hate to beat a dead horse, but may I suggest using a pure function?

import sys

def main(stdin):
  for line in stdin:
    print("You said: " + line.strip())

if __name__ == "__main__":
  main(sys.stdin)

This approach is nice because main is dependent purely on its input and you can unit test it with anything that obeys the line-delimited input stream paradigm.