file-descriptor

I want to create a file descriptor in C whose value i will specify in code. I have a integer variable which specifies the value of file descriptor to be created. For example i may need a file descriptor whose value is 5 and later associate that with the file named "sample.dat" . You need dup2() http://linux.die.net/man/2/dup fd = open ("sample.dat", O_RDONLY); open the file dup2 (fd, 5); and copy the file descriptor fd into the descriptor number 5 now you can do read (5, buffer, BUFF_MAX); or also use fd to access the same file. You need to close the fd explicitly if you do not need it. As

I have two processes on Linux, A & B. I want to share the file descriptor from process A with process B, now I just serialize it to a char* and pass it to the execl parameters, but that doesn't work. A.c looks like this: union descriptor{ char c[sizeof(int)]; int i; } fd; pid_t pid; fd.i = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); // Perform other socket functions pid = fork(); if(pid == 0){ // Read data from socket if(execl("./B", fd.c, NULL) < 0){ exit(EXIT_FAILURE); }else( exit(EXIT_SUCCESS); } }else if(pid < 0){ exit(EXIT_FAILURE); }else{ waitpid(pid, NULL, 0); } B.c looks like this:

I had a use case for a group chat server where the server had to write a common string to all clients' socket. I had then addressed this by looping through the list of file descriptors and writing the string to each of the file descriptors. Now I am thinking of finding a better solution to the problem. Is it possible to do this by a single function call from the server by using the tee system call in linux. I want the output of one tee to go to the next tee as well to a clients socket. I am wondering if I can dup the file descriptor of one end of the tee to the clients socket and get the

If you want to overwrite a file with Bash, this is easy echo "Hello world" > hosts This does not seem to work with a file descriptor $ exec 3<> hosts $ echo "Hello world" >&3 $ cat hosts Hello world $ echo "Hello world" >&3 $ cat hosts Hello world Hello world That's correct. The mode in which a file is opened is determined when the shell calls open(2) . When you DUP2 an FD (in any language), the flags that were set when the file was opened are shared between open FDs . In your case, O_TRUNC can only be specified when the file is actually opened. The important thing to know is that the mode and

How can I increase the file descriptors limit in nginx? There are several ways to increase file descriptors: Edit /etc/security/limits.conf and set nofile soft and hard limits for the nginx user. Set $ULIMIT in /etc/default/nginx. The nginx init.d script set ulimit $ULIMIT https://gist.github.com/aganov/1121022#file-nginx-L43 Set worker_rlimit_nofile in nginx.conf http://wiki.nginx.org/NginxHttpMainModule#worker_rlimit_nofile Does setting limits in limits.conf affect nginx when started using init.d script on boot? Do I have to use ulimit $ULIMIT in the init script or can worker_rlimit_nofile