python stdin example

soinput.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

'''
usage:
cat about.txt | python soinput.py
'''

import sys

def read_in():
    lines = sys.stdin.readlines()
    for i in range(len(lines)):
        lines[i] = lines[i].replace('\n','')
    #print lines
    return lines

def main():
    lines = read_in()
    print lines

if __name__ == '__main__':
    main()

def read_in():
   return [x.strip() for x in sys.stdin.readlines() ]

Concrete example where data flows into script using stdin from some previous program (another script). Line by line explanations for code below can be found here

# stdin.py
sys.stdout = fsock
print("15\n"
"A\n"
"B\n"
"C\n"
"D\n"
"E\n"
"F\n"
"G\n"
"H")
sys.stdout = saveout
fsock.close()

# stdin.py
def read_in():
    return {x.strip() for x in sys.stdin}

def main():
    lines = read_in()
    for line in lines:
        print(line)

if __name__ == '__main__':
    main()

In the console, run this to see above working. Why this works is also explained here

>>>Python3.5 stdout.py
>>>cat out.log | Python3.5 stdin.py

If you use a set ( { ... } ) for the reading of lines, you won't necessarily get them back in the same order, though, right?

return {x.strip() for x in sys.stdin}

You probably want to be using a list comprehension instead, so the read input will stay in the order of having been read:

return [x.strip() for x in sys.stdin]

Thanks for the gist! I've used it to set up an alias to urlencode strings like so, maybe this is helpful to someone:

python3 -c 'import sys; from urllib.parse import quote; print(quote(sys.stdin.readlines()[0]))'

Most likely you don't want to remove all whitespace from the line, only the trailing newline

def read_in():
   return [x.rstrip('\n') for x in sys.stdin ]