/* simple_read.c*/
#include<unistd.h> /* read, write */
#include<stdlib.h> /* exit */
int main()
{
/*
#include <unistd.h>
size_t read(int fildes, void *buf, size_t nbytes);
#include <unistd.h>
size_t write(int fildes, const void *buf, size_t nbytes);
#include <stdlib.h>
void exit(int status);
*/
/*When a program starts, it usually has three of these descriptor
already opened. 1:Standard input, 2:Standard output, 3:Standard error
*/
char buffer[128];
int nread;
/*copies the first 128 bytes of the standard input to the standard output. It copies
all of the input if there are less than 128 bytes.*/
nread = read(0,buffer, 128);
if(nread == -1)
write(2, "A read error has occurred\n", 26);
if((write(1,buffer,nread)) != nread)
write(2, "A write error has occurred\n", 27);
/* When a program exits, all open file descriptors are automatically closed,
so we don't need to close them explicitly */
exit(0);
}
#以下実行例
$ gcc -o simple_read simple_read.c
$ ./simple_read
Hello goodbye
Hello goodbye
$ echo "Hello, goodbye" | ./simple_read
Hello, goodbye
