file-descriptor

I'm seeking for ways to write data to the existing process's STDIN from external processes, and found similar question How do you stream data into the STDIN of a program from different local/remote processes in Python? in stackoverlow. In that thread, @Michael says that we can get file descriptors of existing process in path like below, and permitted to write data into them on Linux. /proc/$PID/fd/ So, I've created a simple script listed below to test writing data to the script's STDIN (and TTY ) from external process. #!/usr/bin/env python import os, sys def get_ttyname(): for f in sys.stdin,

Can someone tell me why this does not work? I'm playing around with file descriptors, but feel a little lost. #!/bin/bash echo "This" echo "is" >&2 echo "a" >&3 echo "test." >&4 The first three lines run fine, but the last two error out. Why? File descriptors 0, 1 and 2 are for stdin, stdout and stderr respectively. File descriptors 3, 4, .. 9 are for additional files. In order to use them, you need to open them first. For example: exec 3<> /tmp/foo #open fd 3. echo "test" >&3 exec 3>&- #close fd 3. For more information take a look at Advanced Bash-Scripting Guide: Chapter 20. I/O Redirection

Possible Duplicate: Getting a FILE* from a std::fstream I am working on Linux and file descriptors are the main model in this OS. I was wondering whether is there any library or any way to retrieve the native Linux file descriptor starting from a C++ std::fstream . I thought about boost::iostream since there is a class called file_descriptor but I understood that its purpose is different from the one I want to achieve. Do you know some way to do that? You can go the other way: implement your own stream buffer that wraps a file descriptor and then use it with iostream instead of fstream . Using

I am trying to send some file descriptor by linux socket, but it does not work. What am I doing wrong? How is one supposed to debug something like this? I tried putting perror() everywhere it's possible, but they claimed that everything is ok. Here is what I've written: #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <string.h> #include <sys/wait.h> #include <sys/socket.h> #include <sys/types.h> #include <fcntl.h> void wyslij(int socket, int fd) // send fd by socket { struct msghdr msg = {0}; char buf[CMSG_SPACE(sizeof fd)]; msg.msg_control = buf; msg.msg_controllen =

Is there a portable way (POSIX) to get the highest allocated file descriptor number for the current process? I know that there's a nice way to get the number on AIX, for example, but I'm looking for a portable method. The reason I'm asking is that I want to close all open file descriptors. My program is a server which runs as root and forks and execs child programs for non-root users. Leaving the privileged file descriptors open in the child process is a security problem. Some file descriptors may be opened by code I cannot control (the C library, third party libraries, etc.), so I cannot rely