UM_ATTACH(1)

💖 NAME 💖

um_attach — the user command from um-ViewOS, the user-mode implementation of OSVIEW — A Process with a View 🌈

Like, this is literally the manual for the um_attach command, bestie. It's a whole vibe.

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✨ SYNOPSIS ✨

um_attach pid0

And when you mess it up, the exact string it hits you with is Usage:um_attach pid0 — verbatim, pid0 and all. I'm not fixing it, I'm reporting it. 🫶

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🎀 DESCRIPTION 🎀

okay so here's the tea ☕. This file is the um_attach user command, and it is part of um-ViewOS — the user-mode implementation of OSVIEW — A Process with a View.

It takes exactly one thing on the command line, and that thing is a pid. It hands that pid to atoi(), then calls:

um_attach(atoi(argv[1]))

That's it. That's the whole personality. 💅

The rules of engagement are:

1. If argc != 2 — meaning you gave it zero args or three args or a whole novel — it calls usage() and returns 1.
2. Otherwise it calls um_attach(atoi(argv[1])). If that comes back < 0, it goes perror("um_attach") and returns -1.
3. If it comes back happy, it returns 0. slay. ✨

um_attach() itself is declared over in um_lib.h — that's where the real magic lives, this file is just the little front door. 🚪

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🌸 USAGE 🌸

the usage() function, exactly as written:

void usage() { fprintf(stderr, "Usage:um_attach pid0); }

It writes to stderr, not stdout. It fires when argc != 2, and right after it fires, main returns 1. No cap. 😭

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💅 EXIT STATUS 💅

• 0 — um_attach(atoi(argv[1])) came back non-negative. Everything ate, nothing left on the plate. 👑
• 1 — you didn't pass exactly one argument, so usage() printed and main returned 1.
• -1 — um_attach(atoi(argv[1])) returned < 0, so perror("um_attach") ran and main returned -1.

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🦋 ERRORS 🦋

When the attach call fails, you get:

perror("um_attach")

which prints its message to stderr with the prefix um_attach. That's the whole error story — it's giving "short and honest". 💀

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🧚 WHAT IT'S BUILT ON 🧚

The includes, exactly as listed:

• #include <config.h>
• #include <stdio.h>
• #include <stdlib.h>
• #include <unistd.h>
• #include <getopt.h>
• <config.h> — yes, config.h shows up a second time up in here. I'm not gonna pretend I know why, I'm just telling you what's written. 🙈
• #include <um_lib.h>

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👑 THE MAIN CHARACTER 👑 (main)

int main(int argc, char *argv[]) {
  if (argc != 2) {
    usage();
    return 1;
  } else {
    if (um_attach(atoi(argv[1])) < 0) {
      perror("um_attach");
      return -1;
    } else
      return 0;
  }
}

Look at her. Twelve lines, zero notes. 😌

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⭐ COPYRIGHT & LICENSE ⭐

Copyright 2008 Renzo Davoli University of Bologna - Italy 🎓

This program is free software — you can redistribute it and/or modify it under the terms of the GNU General Public License, version 2, as published by the Free Software Foundation. 📜

It's distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY — without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. (dramatic but true, bestie, that's a real caveat, don't skip it 🚨) See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

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and that's the whole page, bestie — go forth and attach responsibly 🦋✨

signing off from the very last line: this page carries $Id: um_add_service.c 362 2007-06-08 14:31:54Z rd235 $ — yes the file is named um_add_service.c in its own Id tag while documenting um_attach, and honestly? iconic behavior. 🎀 no notes. 💖