Write a C program that creates $3$ processes $($one parent and two children$).$ The processes will relay information to each other in following fashion:

$$ The first process $($parent$)$ reads a text file $$input$.$txt$$ line by line.

$$ The second process reads from the first pipe and reverse letters $($Capital to small and small to

$$ capital$).$

$$ The third process reads from the second pipe and outputs to a file e$.$g$.,$output$.$txt$.$

Please complete the missing parts in the provided skeleton code and don$$t change any other parts. Also, create

a text file, which contains several text lines. The file will be used as an input for your program. Lastly, please highlight what code you added in another color so I can see what additions you made.

#include

#include

#include

#include

#include

#define READ$\_$END $0$

#define WRITE$\_$END $1$

int main$($int argc, char$*$ argv$[])\{$

$//$ declare pipes

int fd$1[2],$ fd$2[2]$;

pid$\_$t pid;

if $($pipe$($fd$1)==-1||$ pipe$($fd$2)==-1)\{$

fprintf$($stderr$,$ "Pipe failed"$)$;

return $1$;

$\}$

pid $=$ fork$()$;

if $($pid $<0)\{$

fprintf$($stderr$,$ "Fork Failed"$)$;

return $1$;

$\}$

if $($pid $>0)\{//$ Parent process

close$($fd$1[$READ$\_$END$])$;

close$($fd$2[$WRITE$\_$END$])$;

FILE$*$ fp $=$ fopen$("$input$.$txt$","$r$")$;

if $($fp $==$ NULL$)\{$

fprintf$($stderr$,$ "Failed to open file

$")$;

exit$(1)$;

$\}$

char line$[$BUFSIZ$]$;

while $($fgets$($line$,$ BUFSIZ, fp$))\{$

write$($fd$1[$WRITE$\_$END$],$ line, strlen$($line$))$;

memset$($line$,0,$ BUFSIZ$)$;

read$($fd$2[$READ$\_$END$],$ line, BUFSIZ$)$;

printf$("\%$s$",$ line$)$;

$\}$

fclose$($fp$)$;

close$($fd$1[$WRITE$\_$END$])$;

close$($fd$2[$READ$\_$END$])$;

$\}$

else $\{//$ Child process

pid $=$ fork$()$;

if $($pid $>0)\{//$ Second process

close$($fd$1[$WRITE$\_$END$])$;

close$($fd$2[$READ$\_$END$])$;

char line$[$BUFSIZ$]$;

while $($read$($fd$1[$READ$\_$END$],$ line, BUFSIZ$))\{$

for $($int i $=0$; i $<$ strlen$($line$)$; i$++)\{$

$//$ Change lower to upper and upper to lower cases

$//$ write code here

$\}$

write$($fd$2[$WRITE$\_$END$],$ line, strlen$($line$))$;

memset$($line$,0,$ BUFSIZ$)$;

$\}$

close$($fd$1[$READ$\_$END$])$;

close$($fd$2[$WRITE$\_$END$])$;

$\}$

else $\{//$ Third process

$//$ Close unused pipes

$//$ write code here

FILE$*$ fp $=$ fopen$("$output$.$txt$","$w$")$;

char line$[$BUFSIZ$]$;

while $($read$($fd$2[$READ$\_$END$],$ line, BUFSIZ$))\{$

$//$ prints to the output.txt file

$//$ write code here

$\}$

fclose$($fp$)$;

close$($fd$2[$READ$\_$END$])$;

$\}$

$\}$

return $0$;

$\}$