003 Linux System Programming - EmbLogic

003.06.IPC Mechanism.FIFOs

spatlou — Fri, 07 Aug 2020 07:48:34 +0530

You are invited to put in all queries/resolutions/advice/articles/discussion related to

003.06.IPC Mechanism.FIFOs

here...

01.Processes-and-Resources

pravjot — Tue, 09 Jan 2024 04:37:29 +0530

All queries, discussions, updates and clarifications related to...

01.Processes-and-Resources

should be posted here.

18. Using the SA_SIGINFO Flag

pravjot — Mon, 24 Jun 2024 01:00:24 +0530

18. Using the SA_SIGINFO Flag

What is the SA_SIGINFO flag in the sigaction structure, and how does it modify the behavior of signal handling? Provide an example that demonstrates using SA_SIGINFO to handle the SIGINT signal and retrieve extended information about the signal.

Tracking-Processes

pravjot — Sun, 07 Jan 2024 12:45:07 +0530

All queries, discussions, updates and clarifications related to

Topic.003.01.11.Tracking-Processes

should be posted here.

Client Server Application using IPC and Synchronization techniques.

spatlou — Fri, 06 Feb 2015 10:36:50 +0530

System
programming is the activity of programming system software. The
systems programming aims to produce software which provides services to
the computer hardware. It requires a greater degree of hardware
awareness. We need to create an Inter Process Communication mechanism
based client-Server setup. There should be a Server program, Some
clients would send requests to the server and the server would further
find the appropriate client to process the request. The server
then invokes the new client so as to process the request. The new client
should then send the result back to the server, which then sends it
forward to the requesting client

Client Server Application - Multi threaded server.

spatlou — Sat, 10 Jan 2015 15:14:47 +0530

Please user this thread for discussion for - as mentioned.

Design of Client-Server application

kumar.neer2010 — Wed, 19 Feb 2014 13:23:35 +0530

Hi All,

I am confused in design for client-server project.

i tried client-server application with pipe but facing lots of issues.

please let me know how should i try client-server application with pipe and with fifo.

Orphan Process and Adoption

spatlou — Mon, 05 Apr 2021 08:42:53 +0530

Copy-on-write

spatlou — Mon, 18 Nov 2019 12:43:38 +0530

What is Copy-on-write

What is Zombie?

spatlou — Mon, 05 Apr 2021 08:42:36 +0530

Client-Server Communication using FIFOs for more then 1 clients

spatlou — Thu, 03 May 2018 16:56:20 +0530

Minutes of Meeting:
Client Server using FIFO.

Client Server Implementation. 1 Client 1 Server 1 Vendor

spatlou — Sun, 19 Apr 2015 16:00:59 +0530

RCS file: header.h,v
Working file: header.h
head: 1.1
branch:
locks: strict
access list:
symbolic names:
keyword substitution: kv
total revisions: 1;	selected revisions: 1
description:
This is the base aedder file.
Included stdio.h, unistd.h, fcntl.h
----------------------------
revision 1.1
date: 2015/04/19 09:28:45;  author: root;  state: Exp;
Initial revision
=============================================================================

03.Process Management. Duplication

spatlou — Thu, 24 Sep 2020 05:53:25 +0530

All queries, discussions, updates and clarifications related to

003.03.Process Management

should be posted here.

16-17-IPC using Shared Memory

spatlou — Sat, 04 Jul 2020 10:15:23 +0530

All queries, discussions, updates and clarifications related to

Shared Memory

should be posted here.

14-15-IPC using Message Queues

spatlou — Sat, 04 Jul 2020 09:29:34 +0530

All queries, discussions, updates and clarifications related to

Message Queues

should be posted here.

Client Server Implementstion using IPC and threads

spatlou — Wed, 23 Dec 2015 15:21:45 +0530

RCS file: header.h,v
Working file: header.h
head: 1.2
branch:
locks: strict
access list:
symbolic names:
keyword substitution: kv
total revisions: 2;   selected revisions: 2
description:
Included stdio.h
----------------------------
revision 1.2
date: 2015/12/23 09:41:02; author: root; state: Exp; lines: +2 -0
Included fcntl.h and unistd.h
----------------------------
revision 1.1
date: 2015/12/23 09:22:04; author: root; state: Exp;
Initial revision
=============================================================================
CS file: request.h,v
Working file: request.h
head: 1.1
branch:
locks: strict
access list:
symbolic names:
keyword substitution: kv
total revisions: 1;    selected revisions: 1
description:
This header file describes the request structure.
----------------------------
revision 1.1
date: 2015/12/23 09:22:16; author: root; state: Exp;
Initial revision
=============================================================================
RCS file: server.c,v
Working file: server.c
head: 1.5
branch:
locks: strict
access list:
symbolic names:
keyword substitution: kv
total revisions: 5;    selected revisions: 5
description:
Project: Client Server Using IPC and Threads.
This is going to be the main server source file.
----------------------------
revision 1.5
date: 2015/12/23 09:49:02; author: root; state: Exp; lines: +1 -0
*** empty log message ***
----------------------------
revision 1.4
date: 2015/12/23 09:45:50; author: root; state: Exp; lines: +5 -0
The server tries to read the request from the pipe.
----------------------------
revision 1.3
date: 2015/12/23 09:38:46; author: root; state: Exp; lines: +16 -1
Created a pipe for accepting requests.
Forks a child which further execl()'s a client process, whilh would write the request.
----------------------------
revision 1.2
date: 2015/12/23 09:25:09; author: root; state: Exp; lines: +9 -0
Created pipe for accepting the request.
----------------------------
revision 1.1
date: 2015/12/23 09:21:36; author: root; state: Exp;
Initial revision
=============================================================================

RCS file: client1.c,v
Working file: client1.c
head: 1.2
branch:
locks: strict
access list:
symbolic names:
keyword substitution: kv
total revisions: 2;    selected revisions: 2
description:
This client will be invoked through the server and will get the pipe file descriptors as CLA.
It prepares the request and writes to the server through thr pipe.
The pippe file descriptors captured from CLA are converted from string to int using atoi()
----------------------------
revision 1.2
date: 2015/12/23 09:43:37; author: root; state: Exp; lines: +1 -1
Declared wfd
----------------------------
revision 1.1
date: 2015/12/23 09:37:17; author: root; state: Exp;
Initial revision
=============================================================================

003.07.Signals and Handlers

spatlou — Thu, 20 Feb 2020 19:51:05 +0530

Various key combinations for generating Signals

$ stty -a | perl -ne'
   $b{$1}=$2 while /\b(intr|quit|susp|stop|start)\s*=\s*([^\s;]+)/g;
   END {
      print "SIGINT:  $b{intr}\n";
      print "SIGQUIT: $b{quit}\n";
      print "SIGTSTP: $b{susp}\n";
      print "SIGSTOP: $b{stop}\n";
      print "SIGCONT: $b{start}\n";
   }
'
SIGINT:  ^C
SIGQUIT: ^\
SIGTSTP: ^Z
SIGSTOP: ^S
SIGCONT: ^Q

Duplicating Processes using Fork.

spatlou — Mon, 27 Oct 2014 16:38:52 +0530

Fork>
Syntax #include
#include
pid_t fork(void);
The call to fork in the parent
returns the PID of the new child
process
The new process continues to execute just like the original
In the child process the call to fork returns 0
This helps to differentiate between the parent and child

Processes Creation

spatlou — Sat, 26 Sep 2015 09:46:24 +0530

The PCE struct task_struct is found at
/usr/src/kernels/2.6.43.8-1.fc15.x86_64/include/linux

Interview Questions: Project 03

spatlou — Sat, 19 Aug 2017 14:50:26 +0530

Please post the Interview Questions and Answers related to Linux Programming using Inter-Process Communication, Synchronization and Threads here.

LogFile fork() execl() and passing file descriptor

spatlou — Wed, 23 Dec 2015 15:23:08 +0530

RCS file: header.h,v
Working file: header.h
head: 1.3
branch:
locks: strict
   root: 1.3
access list:
symbolic names:
keyword substitution: kv
total revisions: 3;   selected revisions: 3
description:
INcluded stdio.h
----------------------------
revision 1.3   locked by: root;
date: 2015/12/22 09:30:21; author: root; state: Exp; lines: +1 -0
Included string.h
----------------------------
revision 1.2
date: 2015/12/22 08:40:07; author: root; state: Exp; lines: +2 -0
Included unistd.h and fcntl.h
----------------------------
revision 1.1
date: 2015/12/22 08:36:10; author: root; state: Exp;
Initial revision
=============================================================================

RCS file: processes.c,v
Working file: processes.c
head: 1.21
branch:
locks: strict
   root: 1.21
access list:
symbolic names:
keyword substitution: kv
total revisions: 21;   selected revisions: 21
description:
This program series is used for learning prosess management
----------------------------
revision 1.21   locked by: root;
date: 2015/12/22 09:31:53; author: root; state: Exp; lines: +1 -1
/
Declared count.
----------------------------
revision 1.20
date: 2015/12/22 09:31:17; author: root; state: Exp; lines: +2 -1
Printing the no of bytes written to file.
----------------------------
revision 1.19
date: 2015/12/22 09:30:06; author: root; state: Exp; lines: +4 -1
Writing to the file.
----------------------------
revision 1.18
date: 2015/12/22 09:23:38; author: root; state: Exp; lines: +3 -1
We have a file descriptor and we want to pass this file descriptor to tnother process using execl().
As execl() takes only strings as argument but file descriptor is an integer.
So we need to conver int ot string .
this is done in our program using sprintf().
Now, the file descriptor is passed as argumne through execl().
----------------------------
revision 1.17
date: 2015/12/22 09:21:08; author: root; state: Exp; lines: +2 -2
Reverting back to execl() after testing execv()
----------------------------
revision 1.16
date: 2015/12/22 09:18:59; author: root; state: Exp; lines: +1 -1
*** empty log message ***
----------------------------
revision 1.15
date: 2015/12/22 09:18:27; author: root; state: Exp; lines: +1 -1
*** empty log message ***
----------------------------
revision 1.14
date: 2015/12/22 09:17:18; author: root; state: Exp; lines: +1 -1
*** empty log message ***
----------------------------
revision 1.13
date: 2015/12/22 09:16:42; author: root; state: Exp; lines: +2 -6
*** empty log message ***
----------------------------
revision 1.12
date: 2015/12/22 09:15:18; author: root; state: Exp; lines: +3 -3
se
----------------------------
revision 1.11
date: 2015/12/22 09:14:40; author: root; state: Exp; lines: +4 -4
*** empty log message ***
----------------------------
revision 1.10
date: 2015/12/22 09:14:06; author: root; state: Exp; lines: +4 -4
se
----------------------------
revision 1.9
date: 2015/12/22 09:12:42; author: root; state: Exp; lines: +6 -1
replacing the execl() with execv().
i.e. instead of list of string arguments,,,
Now, we pass a vector of arguments.
----------------------------
revision 1.8
date: 2015/12/22 09:03:15; author: root; state: Exp; lines: +3 -2
The parent process is now going to wait for the child process to finish its execution.
We neeed to see that the parent process waits for child or new process or waits indefinitely.
----------------------------
revision 1.7
date: 2015/12/22 08:59:45; author: root; state: Exp; lines: +1 -0
Testing for.. when the parent process finiches and terminates.
Before/After the child process.
----------------------------
revision 1.6
date: 2015/12/22 08:56:42; author: root; state: Exp; lines: +17 -5
Forkign a child process.
Then ececl'ing a process from child process.
This should not overwrite the parent process, but the child process will be killed.
The new process will take over the PBC of child process and a new process context would be created for it.
----------------------------
revision 1.5
date: 2015/12/22 08:50:19; author: root; state: Exp; lines: +1 -1
Passing some string arguments to the replacing process.
----------------------------
revision 1.4
date: 2015/12/22 08:46:40; author: root; state: Exp; lines: +3 -0
Invoking the new process using process replacement , execl().
----------------------------
revision 1.3
date: 2015/12/22 08:40:39; author: root; state: Exp; lines: +1 -1
*** empty log message ***
----------------------------
revision 1.2
date: 2015/12/22 08:39:47; author: root; state: Exp; lines: +13 -1
Opening the file whose name is collected through command line arguments.
----------------------------
revision 1.1
date: 2015/12/22 08:35:34; author: root; state: Exp;
Initial revision
=============================================================================

RCS file: reader.c,v
Working file: reader.c
head: 1.5
branch:
locks: strict
   root: 1.5
access list:
symbolic names:
keyword substitution: kv
total revisions: 5;   selected revisions: 5
description:
This peogram should be invoked through execl()
----------------------------
revision 1.5   locked by: root;
date: 2015/12/22 09:36:20; author: root; state: Exp; lines: +1 -1
*** empty log message ***
----------------------------
revision 1.4
date: 2015/12/22 09:35:13; author: root; state: Exp; lines: +2 -1
Converting the file descriptor from string to integer as the file descriptor arrved through char *argv[] whils is a string ... to integer.
----------------------------
revision 1.3
date: 2015/12/22 09:34:04; author: root; state: Exp; lines: +4 -2
Reading from the file whose file descriptor was passed through command line.
----------------------------
revision 1.2
date: 2015/12/22 08:50:38; author: root; state: Exp; lines: +3 -0
Accepting and printing command line arguments.
----------------------------
revision 1.1
date: 2015/12/22 08:47:04; author: root; state: Exp;
Initial revision
=============================================================================

IPC

arjunchamyal — Fri, 21 Mar 2014 04:11:37 +0530

facing problem to read in processing client from server.

communication with pipe

iittashish447 — Fri, 14 Mar 2014 07:49:38 +0530

Today created pipe and communication between files are established.

handler function

gagan7230 — Wed, 12 Mar 2014 02:51:28 +0530

what is handler function

Communication with pipe

iittashish447 — Sat, 22 Mar 2014 07:45:11 +0530

The primitive for creating a pipe is the `pipe' function. This creates
both the reading and writing ends of the pipe. It is not very useful
for a single process to use a pipe to talk to itself. In typical use,
a process creates a pipe just before it forks one or more child
processes (*note Creating a Process::). The pipe is then used for
communication either between the parent or child processes, or between
two sibling processes.
The file discriptor for reading pipe is [0]& for write [1].

ipc

sprashant678 — Fri, 21 Mar 2014 04:15:18 +0530

I have done today ipc using pipes for single client.

pipe

poonam.kumari58 — Fri, 21 Mar 2014 04:14:49 +0530

how to read and write in processing client from server ????.
is wait required at server end or processing client end.

05.IPC using Pipes

akshatembdev — Fri, 21 Mar 2014 03:22:05 +0530

Pipes are basis of INTERPROCESS COMMUNICATION, It is form of data transfer from one process to another. Pipes generally communicate in HALF DUPLEX MODE i.e at one time only one process can input in pipe. One process writes in pipe and other process reads from that pipe created. Default size of a pipe is 64k, It uses same concept of circular queue.
Pipe function has the following prototype int pipe(int file_descripter[2]);
It fills this array with two new file descripters and returns a zero on success else returns -1 indicating failure.
WORKING: The writter will go on block on write on pipe full condition if reader is connected ie AUTOMATIC BLOCKING, Reader will go on block on read on pipe empty if the writter is connected, In these conditions we need a terminal handler.
Pipe is always connected between parent and hijacked child for one way communication, Sometimes FIFO(named pipes) are used for connecting a process to unrelated process without creating child.

Design of Client-Server application

kumar.neer2010 — Wed, 19 Feb 2014 13:22:00 +0530

Hi All,

I am confused in design for client-server project.

i tried client-server application with pipe but facing lots of issues.

please let me know how should i try client-server application with pipe and with fifo.

ipc with one requesting client is done

gagan7230 — Fri, 21 Mar 2014 02:30:19 +0530

1
2 RCS file: server.c,v
3 Working file: server.c
4 head: 1.1
5 branch:
6 locks: strict
7         root: 1.1
8 access list:
9 symbolic names:
10 keyword substitution: kv
11 total revisions: 1;     selected revisions: 1
12 description:
13 this is server
14 ----------------------------
15 revision 1.1    locked by: root;
16 date: 2014/03/19 07:21:04; author: root; state: Exp;
17 Initial revision
18 =============================================================================

ipc

gagan7230 — Thu, 20 Mar 2014 02:41:43 +0530

data is transfered between client and server and result is stored back in server

pipes

gagan7230 — Sat, 15 Mar 2014 13:17:24 +0530

how can we transfer data bw two or more childs without doing execl in child and without using delay or sleep function.

how to communicate between more than two client using pipes

arjunchamyal — Fri, 14 Mar 2014 07:37:14 +0530

how fork is used between server and client when more than two clients are there.???

A snippet involving fork() system call .

deepakdj26390 — Fri, 14 Mar 2014 02:23:52 +0530

int main()
{
if(fork() || fork())
{
printf("Inside fork");
}
printf("Outside fork");
}

predict the output?

pipes

gagan7230 — Thu, 13 Mar 2014 01:34:20 +0530

implemented interprocess communication using pipes