How to Make a Program Think It\'s Running in a Terminal?

How to Emulate a TTY for a Program

When a program interacts with stdin, it may behave differently based on whether it is a terminal or a pipe. To overcome this, you can use a technique called "pseudoterminal" (Pty) emulation to make your program appear as a TTY.

One implementation is provided in the C code below, using the forkpty function. This code sets up a pseudoterminal, forks a child process to execute the desired command, and continuously forwards its output to stdout.

#include <signal.h>
#include <stdlib.h>
#include <sysexits.h>
#include <unistd.h>
#include <util.h>

pid_t child = 0;

void sighandler(int signum) {
  if (child > 0) {
    killpg(child, signum);
    exit(signum);
  }
}

int main(int argc, char *argv[]) {
  if (argc < 2) {
    return EX_USAGE;
  }

  int master;
  child = forkpty(&amp;master, NULL, NULL, NULL);

  if (child == -1) {
    perror("failed to fork pty");
    return EX_OSERR;
  }

  if (child == 0) {
    execvp(argv[1], argv + 1);
    perror("failed to execute command");
    return EX_OSERR;
  }

  signal(SIGHUP, sighandler);
  signal(SIGINT, sighandler);
  signal(SIGTERM, sighandler);

  const int buf_size = 1024;
  char buf[buf_size];
  fd_set fds;
  ssize_t bytes_read;

  while (1) {
    FD_ZERO(&amp;fds);
    FD_SET(master, &amp;fds);

    if (select(master + 1, &amp;fds, NULL, NULL, NULL) > 0 &amp;&amp; FD_ISSET(master, &amp;fds)) {
      bytes_read = read(master, buf, buf_size);
      if (bytes_read <= 0) {
        return EXIT_SUCCESS;
      }

      if (write(STDOUT_FILENO, buf, bytes_read) != bytes_read) {
        perror("failed to write to stdout");
        return EX_OSERR;
      }
    }
  }
}

By integrating this technique, your program can effectively interact with other applications as if it were operating through a terminal.

The above is the detailed content of How to Make a Program Think It\'s Running in a Terminal?. For more information, please follow other related articles on the PHP Chinese website!