Hi
I am trying to modify a C program to work for my needs. Problem is I don’t know any real programming. I would really appreciate it if someone could help me!
Basically it is to get bandwidth speeds from a remote box. I have two terminal commands that get me the up and down speeds.
So how do I in c run the command and set the output to a variable to call later?
Yeah it’s cpu but same idea, best example I can give.
usage=command
command=” cat /proc/stat | grep '^cpu ' ”
Printf (CPU speed is %i , usage)

You open the file with fopen("filename", "r"), and read lines with fgets(buf, sizeof(buf), fp); and scan until you get the lines you want, and print them.

What have you tried?

In the file I have it does it about the same way as you said.

void getValues() {
 char line[100];
 
  remove("/tmp/value.txt");
  system(leftCmd);
  system(rightCmd);
  system(ledCmd);
 lv1=lv2;
 rv1=rv2;
 lev1=lev2;
 
 fr = fopen ("/tmp/value.txt", "r");
 fgets(line, 80, fr) ;
 sscanf (line, "%llu", &lv2);
 fgets(line, 80, fr) ;
 sscanf (line, "%llu", &rv2);
 fgets(line, 80, fr) ;
 sscanf (line, "%llu", &lev2);
 fclose(fr);
}
 
 
void getConfig ()
{
 FILE *fc;
  char key[100];
  char value[200];
  char row[1024];
 
 char *p;
  fc=fopen("current.cfg","r");
  while (!feof(fc) ){
    fgets(row,200,fc);
 
   if (strlen(row)<4) continue;
    if( sscanf(row,"%[^=]=%[^=\n]",key,value)==2 ) {
        if (strlen(key)<4) continue;
 if (strcmp (key,"sleepTime")==0) sleepTime=strtol(value,&p, 10);
 if (strcmp(key,"leftComunity")==0) strcpy(leftComunity,value);
 if (strcmp(key,"leftIP")==0) strcpy(leftIP,value);
 if (strcmp(key,"leftMIB")==0) strcpy(leftMIB,value);
 if (strcmp(key,"rightComunity")==0) strcpy(rightComunity,value);
 if (strcmp(key,"rightIP")==0) strcpy(rightIP,value);
 if (strcmp(key,"rightMIB")==0) strcpy(rightMIB,value);
 if (strcmp(key,"ledComunity")==0) strcpy(ledComunity,value);
 if (strcmp(key,"ledIP")==0) strcpy(ledIP,value);
 if (strcmp(key,"ledMIB")==0) strcpy(ledMIB,value);
 if (strcmp(key,"leftMax")==0) leftMax=strtol (value, &p, 10);
 if (strcmp(key,"rightMax")==0) rightMax=strtol (value, &p, 10);
 if (strcmp(key,"ledMax")==0) ledMax=strtol (value, &p, 10);
   }
}   
 fclose(fc);
 
 sprintf(leftCmd,"snmpget -v 1 -c \"%s\"  %s %s   | awk '{print $4 >> \"/tmp/value.txt\" }'",    leftComunity,leftIP,leftMIB);
 sprintf(rightCmd,"snmpget -v 1 -c \"%s\"  %s %s   | awk '{print $4 >> \"/tmp/value.txt\" }'",   rightComunity,rightIP,rightMIB);
 sprintf(ledCmd,"snmpget -v 1 -c \"%s\"  %s %s   | awk '{print $4 >> \"/tmp/value.txt\" }'", ledComunity,ledIP,ledMIB);
 }
 
int main(int argc, char ** argv)
{
 int difference;
 //struct ntptimeval start, elapsed;
 
 
 struct usb_dev_handle * perf_fs_usb = usb_perf_fs_usb_open();
 getConfig();
 
 printf("Starting monitoring:\n");
 ntp_gettime(&start);
 getValues();
while(1) {
usleep(sleepTime);
 getValues();
 ntp_gettime(&elapsed);
 difference=difference_micro(&start, &elapsed) ;
 ntp_gettime(&start);
 left=umin((lv2-lv1)*800/difference/leftMax ,100);
 right=umin((rv2-rv1)*800/difference/rightMax ,100);
 led=umin((lev2-lev1)*800/difference/ledMax ,100);
 printf ("sleep %i ",difference);
 printf ("display: %i %i %i\n",right,left, led);
writeUSB(perf_fs_usb,right,left,led);
 
 
   }

Pardon?

Show the input you have, and the output you want.

Sorry, I mean by taking this

Code:

sprintf(leftCmd,"snmpget -v 1 -c \"%s\" %s %s | awk '{print $4 >> \"/tmp/value.txt\" }'", leftComunity,leftIP,leftMIB);

./check_snmp_int.pl -H 192.168.1.1 -C public -n eth0 -k --label -w 0,0 -c 0,0 -d 15 -MB | grep in | cut -d '=' -f 2| cut -d "/" -f 1| grep [0-9.] | tr -d '[:alpha:]' | awk '{print $1}'

percent=(inspeed/30)*100

printf (current download is %i, percent)

I still have no idea what you mean by 'call in'.

./check_snmp_int.pl -H 192.168.1.1 -C public -n eth0 -k --label -w 0,0 -c 0,0 -d 15 -MB | grep in | cut -d '=' -f 2| cut -d "/" -f 1| grep [0-9.] | tr -d '[:alpha:]' | awk '{print $1}'

FILE *p=popen("./check_snmp_int.pl ...", "r");
char buf[512];
while(fgets(buf, 512, p) != NULL)
{
        printf("Read line %s", buf);
}

pclose(p);

I really appreciate you help me!

I don’t have much real knowledge of this kind of stuff, nor know the technical terms. Most of what I know is just from messing around, one of these days I should actually read a book.

By “call” I mean be able to input a function? into another line. So if these are the right terms.
variable=function
math= (2+1)/2
answer=math
but be able to do that with the command I have, with the output being assigned a variable

Yeah I realized that the command was pretty messy but it was the only way I could figure it out. The original output is

eth0:UP (in=0.0Mbps/out=0.0Mbps):1 UP: OK

writeUSB(perf_fs_usb,downspeed,upspeed)