how do you redirect stdout value from a program to a file?
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Answer Posted / ataraxic
int main(int argc, char *argv[], char *envp[])
{
char *p;
int fd = open("/tmp/mydata", O_CREAT|O_WRONLY);
if ( fd < 0 ) {
perror("open");
return -1;
}
/*
* close(2) system call deletes a descriptor from
* the per-process object reference table. In the
* per-process object reference table, stdin,
* stdout,stderr were placed at positions 0,1,2
* respectively.
*/
close(1);
/*
* Place our file descriptor at the place of stdout.
* Read man dup(2).
*/
dup(fd);
/*
* printf(3) is ultimately calling write(2) with
* first argument as 1
*/
printf("Hello there!\n");
p = getenv("MDEV");
if (p != NULL)
printf("MDEV is: %s\n", p);
p = getenv("SUBSYSTEM");
if (p != NULL)
printf("SUBSYSTEM is: %s\n", p);
return 0;
}
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