linux - Passing hex to bash command in C -

i'm trying port bash script c. i'm having trouble passing hex string bash command. have far.

char buffer[512]; char mp_fmt[] = "\x00\x00\x00\x00\x00\x09\x01\x10\x00\x00\x00\x01\02\x00\x01"; sprintf(buffer,"echo -e \"\x00\x00\x00\x00\x00\x09\x01\x10\x00\x00\x00\x01\02\x00\x01\" | nc 192.168.01.22 500"); //sprintf(buffer,"echo -e \"%s\" | nc 192.168.01.22 500"); system((char *)buffer); 

when run this, compiler returns

test.c:7:5: warning: embedded ‘\0’ in format [-wformat-contains-nul]      sprintf(buffer,"echo \"\x00\x00\x00\x00\x00\x09\x01\x10\x00\x00\x00\x01\02\x00\x01\" | nc 192.168.01.22 500"); 

but when run other sprintf that's commented out, doesn't complain not working because device isn't responding.

also in bash script, how done , response device.

echo -e "\0\0\0\0\0\x9\x1\x10\0\0\0\01\02\0\x01" | nc 192.168.01.22 500 

thanks reading long post.

doing this, don't want 0 bytes literal string \0. so,

sprintf(buffer, "echo \"\\0\\0\\0\\0\\0\\x9\\x10 [...] 

would work.

that being said, there other issues.

the simple 1 is: buffer for? don't have any formatting, use string of command literally!

next: using echo c? really? fork 3(!) processes this. @ least, use popen() nc , fwrite() input string there.

even better: send data socket. there perfecly fine bsd sockets api that, no need call external tool.

[edit]: using sockets yourself, can send raw 0 bytes.

[edit2]: sketchup code

#include <sys/socket.h> #include <netinet/in.h>  [...]  int fd; struct sockaddr_in sin; char mp_fmt[] = "\x00\x00\x00\x00\x00\x09\x01\x10\x00\x00\x00\x01\x02\x00\x01";  fd = socket(af_inet, sock_stream, 0); sin.sin_family = af_inet; sin.sin_addr.s_addr = inet_addr("192.168.1.22"); sin.sin_port = htons(500);  connect(fd, (struct sockaddr *)&sin,sizeof(struct sockaddr_in));  write(fd, mp_fmt, 15);  shutdown(fd, shut_rdwr); close(fd);