General questions about (UNIX) OS architecture

learn more… | top users | synonyms

2
votes
1answer
3k views

child process does not inherit the pending signals from the parent after a fork system call, why?

Could anybody please tell me the reason to why pending signals are not inherited by the child process? On the other hand, the child process inherits the signal handlers and signal mask from the ...
5
votes
1answer
5k views

How can I build a rpm for i386 target on a x86-64 machine?

I am building an rpm using rpmbuild command as: rpmbuild -bb --root <DIRECTORY> --target i386 --define "_topdir <DIRECTORY>" <specfile>.spec When I use my SLED 10 SP3 x86 machine, ...
4
votes
2answers
144 views

When I move a file to a different directory on the same partition, does the file's data actually move on disk?

I could see it going both ways. If the filesystem stores it's directory structure and list of files in each directory, and then points to the disk location of each of the files, it shouldn't require ...
1
vote
1answer
388 views

Can 32-bit and 64-bit CentOS 6.4 servers both be AD domain controllers for the same domain?

If I have two CentOS 6.4 servers, one i386 and the other x86_64, running Samba 4.0.7, will they replicate domain controller data with each other (and from a Windows Server 2003 AD DC) without any ...
11
votes
2answers
3k views

How signals work internally?

In general, to kill processes we generate signals like SIGKILL,SIGTSTP etc. But how is it known who ordered that particular signal, who has sent it to a particular process, and in general how do ...
4
votes
2answers
237 views

Why do we need two file descriptors when creating an unnamed pipe?

I've been reading about unnamed pipes and as I understood them they're implemented as a buffer in memory. When creating the pipe I need to pass an array of size two and it returns two pointers (file ...
3
votes
4answers
2k views

How do file permissions/attributes work? Kernel-level, FS-level or both?

A question that occurred to me earlier: are file permissions/attributes OS- (and therefore kernel-) dependent or are they filesystem-dependent? It seems to me that the second alternative is the more ...
18
votes
2answers
5k views

How does a Linux terminal work?

If you fire up a terminal and call an executable (assuming one thats line oriented for simplicity) you get a reply to the command from the executable. How does this get printed to you (the user) does ...
2
votes
3answers
2k views

How I can emulate a big endian platform on a x86?

I need to get a big endian platform to develop with gcc and g++, what is a solution for that? I know that the SPARC is one of those big endian architectures, but I have no idea what OSs can run on it ...
-9
votes
2answers
351 views

Why is the UNIX kernel so crucial? [closed]

More specifically, how is the UNIX kernel treated differently from other parts of the Operating System?
0
votes
2answers
80 views

How many types of architectures and OSes

I am trying to write a script python script that is supposed to run across all linux based OSes. The python script invokes executables of few existing tools(for example pathload and iperf) that I have ...
5
votes
1answer
625 views

How to know which commands are executed when I do something in GUI

This is for academic purpose. I want to know which commands are executed when we do something in GUI, for example creating a folder. I want to show that both the mkdir shell command and create folder ...
2
votes
3answers
8k views

How does the set-user-ID mechanism work in Unix?

Can someone please explain the set-user-ID mechanism in Unix ? What was the rationale behind this design decision? How is it different from effective user id mechanism ?
2
votes
1answer
1k views

Concept of memory mapping in Unix like systems

Can some one explain in an easy to understand way the concept of memory mappings (achieved by mmap() system call) in Unix like systems ? When do we require this functionality ?
0
votes
1answer
476 views

File permission mechanism in Unix like systems

Can some one please explain with a an example the file permission mechanism in Linux and other Unix like systems ? What are the nine bits for ? Why do we have a group id for a user as well as for a ...
6
votes
4answers
11k views

Difference between system calls and library functions

I have been through the answer of this question but do not quite understand the difference between system calls and library functions. Conceptually, what is the difference between the two?
1
vote
0answers
701 views

Install CentOS in a VirtualBox to a Compact Flash and use it on a mini PC

I got into a very specific situation and want to get to know your opinions. I have got a mini PC with Intel Atom processor which should run CentOS with an upgraded kernel to 3.x and some ...
0
votes
1answer
1k views

Hurd vs Plan9 vs Linux vs eCos vs FreeRTOS what are the main differences specially with Hurd?

Hurd is actually not Unix nor Linux. But more superior says. Where Plan9 and Linux are in the range of Unix/Linux. eCos and FreeRTOS is also completely not unix/linux. What is the main differences ...
3
votes
3answers
2k views

Which arch linux should I download?

I'm going to install Arch linux yet I have to choose between several architectures my computer has. I have an aluminium macbook pro, with a 2.3 GHz Intel Core i5 processor. . The intel webpage tells ...
5
votes
9answers
972 views

Metaphor for the concept of shell?

I'm finding myself helping out some classmates in my computer science class, because I have prior development experience, and I'm having a hard time explaining certain things like the shell. What's a ...
5
votes
2answers
1k views

What's the difference between /etc/rc.d/rc*.d and /etc/rc*.d

I know that rc*.d directories are used at startup, or reboot, or so on time, for starting or stopping programs. Can anybody explain me what's the difference between the rc*.d folders placed under the ...
3
votes
4answers
2k views

What are the books about creating own *nix OS? [closed]

I want to create my own Unix OS. Is there any book that I can learn from, from start?
3
votes
3answers
2k views

How to determine bitness of hardware and OS?

Output of uname -a on my RHEL 5.4 machine is: Linux <machine name> 2.6.18-164.el5 #1 SMP Tue Aug 18 15:51:48 EDT 2009 x86_64 x86_64 x86_64 GNU/Linux Does it mean that hardware is 64 bit ...
8
votes
3answers
7k views

Which Scheduling algorithm is used in Linux?

Recently in an interview I was asked about the Scheduling algorithm used by Linux Operating system. What is the algorithm used any why? Also, what algorithm is used in in real-time operating systems ...
9
votes
4answers
7k views

How are directories implemented in Unix filesystems?

My question is how directories are implemented? I can believe a data structure like a variable e.g. table, array or similar. Since UNIX is Open Source I can look in the source what the program does ...
17
votes
4answers
4k views

How to understand pipes

When I just used pipe in bash, I didn't think more about this. But when I read some C code example using system call pipe() together with fork(), I wonder how to understand pipes, including both ...
22
votes
1answer
32k views

What are software and hardware interrupts, and how are they processed?

I am not sure if I understand the concept of hardware and software interrupts. If I understand correctly, the purpose of a hardware interrupt is to get some attention of the CPU, part of implementing ...
10
votes
3answers
6k views

What is the relationship between system calls, message passing, and interrupts?

I am reading the Wikipedia article for process management. My focus is on Linux. I cannot figure out the relation and differences between system call, message passing and interrupt, in their concepts ...
17
votes
2answers
8k views

Interruption of system calls when a signal is caught

From reading the man pages on the read() and write() calls it appears that these calls get interrupted by signals regardless of whether they have to block or not. In particular, assume a process ...
4
votes
2answers
1k views

Removing zombie process from the process table

Can somebody please explain when parent process receives the exit status of a dead child process via wait, who actually reallocates the memory of the child process and removes it from the process ...
0
votes
1answer
326 views

Which FreeBSD version or ISO for Dell R310?

When I try to install FreeBSD I always get confused as to which iso is the correct one for Rack mounted servers. In their download choices, there are too many versions of FreeBSD Which one is the ...
36
votes
3answers
10k views

Why doesn't cp have a progress bar like wget?

Please note that I don't ask how. I already know options like pv and rsync -P. I want to ask why doesn't cp implement a progress bar, at least as a flag ?
7
votes
3answers
602 views

login and su internals

I am trying to understand how user permissions work in Linux. The kernel boots and starts init as root, right? Init then runs startup scripts and runs getty (agetty), again as root. Agetty just reads ...
12
votes
3answers
684 views

First FreeBSD install. Is there anything I should know about differences between Linux and BSD?

I want to install FreeBSD today on a spare HDD I have lying around. I'd like to give it a trial run, learn a few things, and if it suits me I'll replace my current Ubuntu 10.10 'server/NAS/encoding ...
9
votes
2answers
909 views

Memory management principle used by Linux

Is memory management in the Linux Kernel done using paging or segmentation or both?
4
votes
2answers
556 views

Linux package manager architecture

I am looking for a guide on one of Linux Package manager architectures. For example apt-get (dpkg), or yum (rpm). I want to know how they manage the package list, file list, package versions and so ...
2
votes
2answers
670 views

Resources to learn linux architecture in detail? [closed]

I want to learn the Linux file hierarchy and how the OS works at a deeper level. Are there any ebooks or webpages to learn that?
5
votes
2answers
2k views

Can there be multiple kernels executing at the same time?

I know that Linux OS's are typically multi-programmed, which means that multiple processes can be active at the same time. Can there be multiple kernels executing at the same time?
31
votes
12answers
12k views

Object-oriented shell for *nix

Preface: I love bash and have no intention of starting any sort of argument or holy-war, and hopefully this is not an extremely naive question. This question is somewhat related to this post on ...
34
votes
6answers
12k views

How does a unix or linux system work? [closed]

I would like to know how the OS works in a nutshell: The basic components it's built upon How those components work together What makes unix UNIX What makes it so different from other OSs like ...