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Search found 3 results on 1 pages for 'forkpty'.

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• How to get forkpty to handle redirection and other bash-isms?

  - by Jeremy Friesner

  Hi all, I've got a GUI C++ program that takes a shell command from the user, calls forkpty() and execvp() to execute that command in a child process, while the parent (GUI) process reads the child process's stdout/stderr output and displays it in the GUI. This all works nicely (under Linux and MacOS/X). For example, if the user enters "ls -l /foo", the GUI will display the contents of the /foo folder. However, bash niceties like output redirection aren't handled. For example, if the user enters "echo bar /foo/bar.txt", the child process will output the text "bar /foo/bar.txt", instead of writing the text "bar" to the file "/foo/bar.txt". Presumably this is because execvp() is running the executable command "echo" directly, instead of running /bin/bash and handing it the user's command to massage/preprocess. My question is, what is the correct child process invocation to use, in order to make the system behave exactly as if the user had typed in his string at the bash prompt? I tried wrapping the user's command with a /bin/bash invocation, like this: /bin/bash -c the_string_the_user_entered, but that didn't seem to work. Any hints?

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• forkpty - socket

  - by Alexxx

  Hi, I'm trying to develop a simple "telnet/server" daemon which have to run a program on a new socket connection. This part working fine. But I have to associate my new process to a pty, because this process have some terminal capabilities (like a readline). The code I've developped is (where socketfd is the new socket file descriptor for the new input connection) : int masterfd, pid; const char *prgName = "..."; char *arguments[10] = ....; if ((pid = forkpty(&masterfd, NULL, NULL, NULL)) < 0) perror("FORK"); else if (pid) return pid; else { close(STDOUT_FILENO); dup2(socketfd, STDOUT_FILENO); close(STDIN_FILENO); dup2(socketfd, STDIN_FILENO); close(STDERR_FILENO); dup2(socketfd, STDERR_FILENO); if (execvp(prgName, arguments) < 0) { perror("execvp"); exit(2); } } With that code, the stdin / stdout / stderr file descriptor of my "prgName" are associated to the socket (when looking with ls -la /proc/PID/fd), and so, the terminal capabilities of this process doesn't work. A test with a connection via ssh/sshd on the remote device, and executing "localy" (under the ssh connection) prgName, show that the stdin/stdout/stderr fd of this process "prgName" are associated to a pty (and so the terminal capabilities of this process are working fine). What I am doing wrong? How to associate my socketfd with the pty (created by forkpty) ? Thank Alex

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• Creating a pseudoterminal to make sudo happy

  - by larsks

  I need to automate the provisioning of a cloud instance (running Fedora 17) for which the following initial facts are true: I have ssh-key based access to a remote user (cloud) That user has password-free root access via sudo. Manual configuration is as simple as logging in and running sudo su - and having at it, but I would like to fully automate this process. The trick is that the system defaults to having the requiretty option enabled for sudo, which means that an attempt to do something like this: ssh remotehost sudo yum -y install puppet Will fail: sudo: sorry, you must have a tty to run sudo I am working around this right now by first pushing over a small Python script that will run a command on a pseudoterminal: import os import sys import errno import subprocess pid, master_fd = os.forkpty() if pid == 0: # child process: now that we're attached to a # pty, run the given command. os.execvp(sys.argv[1], sys.argv[1:]) else: while True: try: data = os.read(master_fd, 1024) except OSError, detail: if detail.errno == errno.EIO: break if not data: break sys.stdout.write(data) os.wait() Assuming that this is named pty, I can then run: ssh remotehost ./pty sudo yum -y install puppet This works fine, but I'm wondering if there are solutions already available that I haven't considered. I would normally think about expect, but it's not installed by default on this system. screen can do this in a pinch, but the best I came up with was: screen -dmS sudo somecommand ...which does work but eats the output. Are there any other tools available that will allocate a pseudoterminal for me that are going to be generally available?

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