splab3 - pipeline

Aim

• Learn how to combine several processes in a pipeline using various system calls and pipes.

Task

In this lab you are to write a program in C that solves the same problem as in splab1. The program should use the same tools that you used in splab1, but the shell logic should be done by the C program itself. You should use system calls like fork, exec*, wait/waitpid, open, close, pipe, dup2, exit/_exit.

By shell logic we mean:

• forking processes and waiting results from them
• opening files and i/o redirection (using pipe)
• if statements and loops (e.g. for/while) of bash.

Store your splab1 solution in ./solution/top and splab3 solution in ./solution/top.c.

• See example 1, C program
• See example 2, shell script with for loop, C program using fdopen function
• See example 3, shell script with awk, C program without fdopen

References

0. man fdopen
1. man 2 fork
2. man 2 execve
3. man 2 waitpid
4. man 2 pipe
5. man 2 dup2
6. OSTEP Chapter 5
7. Chapters 6, 24-28 of Linux Programming Interface by Micheal Kerrisk
8. Chapter 5 of Linux System Programming by Robert Love

Credits

• The task was adopted and adapted from http://vseloved.github.io/spos. All credits go to Vsevolod Dyomkin.
• Variants in Russian can be found there