Section 8.2 - Read and Write¶

Question¶

Copy input to output by using read and write system calls.

/*copy input to output */

#include <sys/syscall.h>
#include <unistd.h>

#define BUFSIZ 1024

int main() /* copy input to output */
{
    char buf[BUFSIZ];
    int n;

    while ((n = read(0, buf, BUFSIZ)) > 0)
        write(1, buf, n);
    return 0;
}

Explanation¶

This uses the read and write system calls to copy input to output.

# Compile the program

gcc copy.c -o copy

# Test 1: Echo a simple string

echo "Hello, World!" | ./copy

# Test 2: Multiple lines

cat << 'EOL' | ./copy
Line 1
Line 2
Line 3
EOL

# Test 3: Binary data (create a file with some null bytes)

dd if=/dev/zero bs=1024 count=1 2>/dev/null | ./copy > /dev/null