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Top Forums Programming How to Run a Linux Command and Redirect its output to a socket in C Post 302258408 by Corona688 on Friday 14th of November 2008 01:03:22 PM
Old 11-14-2008
I think you can redirect the output to a stream socket if you fork and exec rather than using popen. This is because the redirection has to happen before you run the program, not after.

Code:
{
  pid_t pid=fork();
  int st;

  if(pid < 0)
  {
    perror("Couldn't fork");
  }
  else if(pid == 0) /* child code, run in a seperate process */
  {
    dup2(sock, 1); /* Duplicate socket's FD over FD #1, aka stdout */
    dup2(sock, 0); /* Duplicate socket's FD over FD #0, aka stdin */
    close(sock); /* Only closes the child's copy.  And the stdin/stdout copies remain. */
    execlp("/bin/echo", "HEY GUYS ALJ AF MY FACE IS A ROTTORN BANANA");
    /* Code below will never happen unless exec fails */
    perror("Couldn't exec");
    exit(1);
  }
  else
  {
    close(sock); /* Parent doesn't need socket anymore */
    waitpid(pid, &st, 0); /* Wait for child to finish */
  }
}

 

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Ns_Exec(3aolserver)					   AOLserver Library Procedures 				       Ns_Exec(3aolserver)

__________________________________________________________________________________________________________________________________________________

NAME
Ns_ExecArgblk, Ns_ExecArgv, Ns_ExecProc, Ns_ExecProcess, Ns_Fork, Ns_GetEnviron, Ns_WaitForProcess, Ns_WaitProcess, ns_fork - External process execution SYNOPSIS
#include "ns.h" int Ns_ExecArgblk(char *exec, char *dir, int fdin, int fdout, char *args, Ns_Set *env) int Ns_ExecArgv(char *exec, char *dir, int fdin, int fdout, char **argv, Ns_Set *env) int Ns_ExecProc(char *exec, char **argv) int Ns_ExecProcess(char *exec, char *dir, int fdin, int fdout, char *args, Ns_Set *env) int Ns_Fork(void) char **Ns_GetEnviron(void) int Ns_WaitForProcess(int pid, int *statusPtr) int Ns_WaitProcess(int pid) int ns_fork(void) _________________________________________________________________ DESCRIPTION
These functions handle fork and exec operations. See files: nsd/exec.c, nsd/tclenv.c and nsthread/fork.c. Ns_ExecArgblk(exec, dir, fdin, fdout, args, env) Executes a command in a child process. Return process id of child process exec'ing the command or -1 on failure. Provides extended error checking and error messages. Ns_ExecArgv(exec, dir, fdin, fdout, argv, env) Execute a command in a child process using fork(2) and execve(2), returns the process id of child process exec'ing the command or -1 on failure. The child sends an extended error message to the parent. Ns_ExecProc(exec, argv) Executes a command in a child process. Returns the process id of the child process exec'ing the command or -1 on failure. Simpli- fies call to Ns_ExecArgv. Ns_ExecProcess(exec, dir, fdin, fdout, args, env) Executes a command in a child process. Returns the process id of the child process exec'ing the command or -1 on failure. Calls Ns_ExecArgblk with same arguments. Ns_Fork() Posix style fork(), using fork1() on Solaris if needed. See fork(2) man page. Calls ns_fork. Ns_GetEnviron() Returns pointer to the environment vector. Ns_WaitForProcess(pid, statusPtr) Wait for child process. Returns NS_OK on success, or NS_ERROR on failure. *statusPtr is set to the exit code of the child process. Ns_WaitProcess(pid) Wait for child process. Calls Ns_WaitForProcess with NULL statusPtr. Returns NS_OK on success, or NS_ERROR on failure. ns_fork() Posix style fork(), using fork1() on Solaris if needed. SEE ALSO
nsd(1), info(n) KEYWORDS
AOLserver 4.0 Ns_Exec(3aolserver)
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