Program for Inter-Process Communication using shared memory

In this lecture on Program for Inter-Process Communication using shared memory, you will learn how shared memory is used for inter process communication in Linux using C language.
Shared Memory is the fastest inter-process communication (IPC) method. The operating system maps a memory segment in the address space of several processes so that those processes can read and write in that memory segment. The overview is as shown below:
Two functions:shmget() and shmat() are used for IPC using shared memory. shmget() function is used to create the shared memory segment while shmat() function is used to attach the shared segment with the address space of the process.
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This lecture is part of the Operating System Lab playlist: • Operating System Lab
For Program code and more details visit: dextutor.com/p...
Reference Videos:
1. IPC using pipe(): • Program for Inter-Proc...
2. IPC using named pipes: • Program for Inter-Proc...
3. IPC using Shared memory: • Program for Inter-Proc...
4. IPC using message queues: • Program for Inter Proc...
5. IPC using popen: • Program for Inter-Proc...
Tools Required:
1. Linux environment
2. Basic knowledge of C Language
3. gcc compiler installed
Reference Links:
Operating System Theory PPTs Link: dextutor.com/c...
Operating System Programs: dextutor.com/c...
Other Playlists:
OS: • Operating System
Linux Essential: • Linux Tutorial For Beg...
RHCSA: • RHCSA Exam Questions |...
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[@aninditasaha0307]

Excellent sir... Simplest... Yet serving the purpose...very helpful for students... Can you make video on message queues?

[@dextutor]

Thanks a lot.. Will upload the video by next week

[@tarunnaik3053]

You made the topics much much more simpler than they are actually sir.Great Explanation 🙇

[@bestdeal3385]

i guess this was the best explanation,thank you sir

[@dextutor]

Thanks.. Keep sharing

[@deletevil]

Great explanation sir! Sir very important thing you didn't tell us. How do we clear/purge the memory occupied by the shared_memory. The first program that was the sender-program had exited. Do we need to call a function from receiver-program to delete the shared_memory?

[@dextutor]

Use memset() function

[@gayathriciddamsetty4826]

Nice explanation 👌. Thank you

[@pythonforfree7297]

outstanding

[@dhanrajv7473]

hello sir could you tell me how to make this as full duplex communication using shared memory .
example it can take input from any 1/2nd process ,and it should receive in another process

[@kanunithu2048]

Thanks a lot, sir

[@gouravshaw6254]

Great explanation 👌👍

[@ayeshaadhikari6123]

Thank you so much sir :) really helpful

[@mazharkhaliq1971]

Thanks for the video 👏👏👏

[@leepakshiyadav1643]

Great explanation.Thanks :)

[@navneetkaurpopli2766]

great lab. Thanks

[@Tom-fx9mk]

How do I determine how much space I need to use for the second argument of shmget? The file I'll be having the processes write to will be in the shared memory. Is 1024 bytes too little in my case (since I'll be having up to 20 processes writing a sentence to the file several times)?

[@dextutor]

Managing space is upto the programmer.. Not all 20 process will be writing at the same time.. So after one process writes some make sure the reader process reads it before another process overwrites it.. If you feel the space is less you can allocate more space..just change 1024 to any number you want

[@abhijitkumarsinha]

why in the receiver program we got different address for shared memory .....it get attached to the same memory segment then it should give the same address

[@dextutor]

Shmat returns the address where the process gets attached to memory segment, not the address of the memory segment. That's why it's different for both process

[@abhijitkumarsinha]

thanks sir@@dextutor

[@hxong4733]

Thank you sir!

[@rabiulhasan4674]

Can You Help Me This Program
Design a program that including 2 sub processes,it receives standard input,through sharing memory,the father process transmits a serial of number(>=10 )to the sub processes,after the sub processes receive the interupt signal from the father process:
1) one subprocess plus the numbers
2)the other subprocess mulitple the numbers
Then through the message queue send the result to the father process,and the father process printf the numbers.

[@dextutor]

Hi.. All the requirements are covered in the videos.. I will list out broadly
1. Create two sub(child processes) using fork
2. Use shared memory to send the input to sub processes
3. Perform individual Calculations
4. Create message queue to send back the results to the parent process

[@vaibhavpallod1023]

Sir use OBS software for recording your videos has poor quality butttt.... your videos are alot informational so thank you so much !

[@dextutor]

Quality issue in terms of audio or video?

[@vaibhavpallod1023]

@@dextutor video

[@dextutor]

Thanks for the suggestion..i will work on that.. Check the latest video on Message queues and share if it was better

[@vaibhavpallod1023]

@@dextutor sure man

[@chinnurpk3519]

Why the address for shared memory changes for sender and receiver??

[@dextutor]

It is the address at which the process gets attached with shared segment. So it can not be same for sender and receiver

[@chinnurpk3519]

@@dextutor ok thanks for clarifying my doubt

[@prathapbillgates]

Nice video. can you make IPC memory passing video?

[@dextutor]

I guess u meant message queues.. The video will be up soon.. Till that time have a look at this link
dextutor.com/program-for-ipc-using-message-queues/

[@chandinikm7129]

I am getting different key value in reciver program...written code as same .

[@rekhavaishnav1462]

Sir who to use Iostat command in wsl

[@rahulpawar811]

In second program in output the first program data we written is not show.. segment fault message show

[@dextutor]

Check your code again..

[@rahulpawar811]

@@dextutor I check but same problem.... even I copy program from your site ,same problem occurs

[@dextutor]

Email me the snapshot of your programs

[@ohm_chiluka]

Getting an error for:
error: invalid conversion from ‘void*’ to ‘char*’ [-fpermissive]
18 | strcpy(shared_memory,buff); //data written to shared memory
| ^~~~~~~~~~~~~
| |
| void*

[@TonyStark-lb2rj]

just typecast it like -> strcpy((char*)shared_memory,buff);

[@nadakudurutejakanth8500]

Supr sir ❤

[@_LAKSHAWADHWANI]

Thanks a lot! :)

[@agpskalaparipaadeex7077]

is it possible When a process communicates with each other, the timestamp is recorded with +5 secs?

[@dextutor]

Use strftime function to fetch the time of communication and then add any additional time you want

[@prashantkassa9162]

Where this shared memory created

[@dextutor]

RAM

[@guidosalescalvano9862]

Did I miss something, or did you not deallocate the memory? How do you deallocate?

[@manjeetkapil1882]

Thanks brother

[@dextutor]

Welcome... Please share among your friends

[@theazkaasmat6647]

how to complie

[@augustinradjou3909]

gcc file_name.c

[@silvianair7423]

Can we turn this into a function???

[@dextutor]

Yes, you can