34 lines
1.2 KiB
C
34 lines
1.2 KiB
C
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/*
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Written By: Prawar Poudel
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This program is supposed to demonstrate the execution of dup2() function
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Please read the manual page first before jumping to run this program
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*/
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#include <stdio.h>
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#include <unistd.h>
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#include <sys/wait.h>
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#include <stdlib.h>
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#include <fcntl.h>
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int main()
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{
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printf("You would expect this to go to your stdout, and it does\n");
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//we will create a file using open function
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char myFileName[] = "test.txt";
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//lets open the file by the name of test.txt
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int myDescriptor = open(myFileName,O_CREAT|O_RDWR|O_TRUNC,0644);
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int id;
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//creating a child that redirects the stdout to test.txt
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// you can use similar functionality for '>' operator
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if((id=fork())==0)
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{
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//lets call dup2 so that out stdout (second argument) is now copied to (points to) test.txt (first argument)
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// what this essentially means is that anything that you send to stdout will be sent to myDescriptor
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dup2(myDescriptor,1); //1 is stdout, 0 is stdin and 2 is stderr
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printf("You would expect this to go to your stdout, but since we called dup2, this will go to test.txt");
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close(myDescriptor);
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exit(0);
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}else
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wait(0);
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printf("This is also printed to the console\n");
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return 0;
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}
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