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Programming
execl() + redirecting output to text files
Post 302168031 by pflynn on Saturday 16th of February 2008 02:24:17 PM
02-16-2008
The problem is: you are giving ls something that actually is the shell's responsability, and that thing is output redirection. Since there is no shell involved in your program, you should perform the redirection of the output by yourself, that is, your program should do the shells's work, first by openning a new file and them redirecting its standard output and standard error to the new file descriptor using the dup2(2) function.
Hope you got the point 
PHP Code:
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int main(int argc, char *argv)
{
int fd; /*file descriptor to the file we will redirect ls's output*/
if((fd = open("dirlist.txt", O_RDWR | O_CREAT))==-1){ /*open the file */
perror("open");
return 1;
}
dup2(fd,STDOUT_FILENO); /*copy the file descriptor fd into standard output*/
dup2(fd,STDERR_FILENO); /* same, for the standard error */
close(fd); /* close the file descriptor as we don't need it more */
/*execl ls */
execl( "/bin/ls" , "ls" , "-la" , (char *) 0 );
return 0;
}
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