stdin

I was working on an assignment where a program took a file descriptor as an argument (generally from the parent in an exec call) and read from a file and wrote to a file descriptor, and in my testing, I realized that the program would work from the command-line and not give an error if I used 0, 1 or 2 as the file descriptor. That made sense to me except that I could write to stdin and have it show on the screen. Is there an explanation for this? I always thought there was some protection on stdin/stdout and you certainly can't fprintf to stdin or fgets from stdout. #include <stdlib.h>

I'm trying to running an external program from a Java program and I'm having trouble. Basically what I'd like to do would be this: Runtime.getRuntime().exec("./extprogram <fileIn >fileOut"); However I've found that that doesn't work - Java apparentls needs to use a Process with input and output streams and other things which I'm not experienced with. I've looked at a number of examples across the internet (many of which are from SO), and there doesn't seem to be a simple standard way of doing this, which for someone who doesn't fully understand what's going on, can be quite frustrating. I'm

This question already has an answer here: How to change the stdin and stdout encoding on Python 2 4 answers While porting code from Python 2 to Python 3, I run into this problem when reading UTF-8 text from standard input. In Python 2, this works fine: for line in sys.stdin: ... But Python 3 expects ASCII from sys.stdin , and if there are non-ASCII characters in the input, I get the error: UnicodeDecodeError: 'ascii' codec can't decode byte .. in position ..: ordinal not in range(128) For a regular file, I would specify the encoding when opening the file: with open('filename', 'r', encoding=

I have a program that interacts with the user (acts like a shell), and I want to run it using python subprocess module interactively. That means, I want the possibility to write to stdin and immediately get the output from stdout. I tried many solutions offered here, but none of them seems to work for my needs. The code I've written based on Running an interactive command from within python import Queue import threading import subprocess def enqueue_output(out, queue): for line in iter(out.readline, b''): queue.put(line) out.close() def getOutput(outQueue): outStr = '' try: while True: #Adds

stdout is line-buffered when connected to a terminal, but I remember reading somewhere that reading (at least from stdin) will automatically flush stdout. All C implementations that I have used have done this, but I can't find it in the standard now. It does make sense that it works that way, otherwise code like this: printf("Type some input: "); fgets(line, sizeof line, stdin); would need an extra fflush(stdout); So is stdout guaranteed to be flushed here? EDIT: As several replies have said, there seems to be no guarantee in the standard that the output to stdout in my example will appear