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);
}
So If I understand it right
sprintf sets �leftcmd� which runs the �snmpget� command and writes the output to values.txt
system(leftcmd) is to run the snmpget again to update numbers
fopen value.txt , sscanf (line, "%llu", &lv2) sets it to lv2
left=lv2
The issue is the command I need to run and how to handle it is different. The original way gets total packets and compares them to get a speed then divides for percentage. The command I have already gives me �4.5� Mbps.
Can I skip the writing it to values.txt and do �print in=$1'. Then to get percentage left=in/leftmax.
Thanks.
Pardon?
Show the input you have, and the output you want.
Sorry, I mean by taking this
sprintf(leftCmd,"snmpget -v 1 -c \"%s\" %s %s | awk '{print $4 >> \"/tmp/value.txt\" }'", leftComunity,leftIP,leftMIB);
And changing | awk print in=$4 }.
By doing that would I be able to call �in� and get the output?
As you can tell this is a bit past my knowledge.
Here is the run down.
I have this command
./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}'
Which in a terminal outputs the current Mbps download �4.3�.
I would like to be able to run the command and set the output to a variable let's say �inspeed�
Then change it to a percentage of bandwidth used. max down =30
percent=(inspeed/30)*100
Then echo the numbers
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}'
This command is extremely inefficient. Can you show complete output from ./check_snmp_int.pl -H 192.168.1.1 -C public -n eth0 -k --label -w 0,0 -c 0,0 -d 15 -MB and highlight the parts you want, please? You can probably do it all in one awk.
You can open commands like
FILE *p=popen("./check_snmp_int.pl ...", "r");
char buf[512];
while(fgets(buf, 512, p) != NULL)
{
printf("Read line %s", buf);
}
pclose(p);
...but it would be far better to simplify the command you have than use it blindly. You may not need C at all.
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
the issue I had was that the numbers scale? Up . for example in=5.0, in=10.4, in=28.3. This was the only way I could figure out how to get the numbers regardless if it was three or two digits.
The main purpose of the program is to write the percentage to an usb device. I figure if I could get as far as printf the percentage, the next step would be easy. Anyways the writing to usb command is just
writeUSB(perf_fs_usb,downspeed,upspeed)
1 Like
OK. I made a fake check_snmp_int.pl which just prints the line "eth0:UP (in=1.0Mbps/out=1.0Mbps):1 UP: OK" so I could test my program. Reading from odd lines like that is precisely what scanf/sscanf/etc are great at:
#include <stdio.h>
int main(void)
{
char buf[512];
float in=0.0, out=0.0;
FILE *p=popen("./check_snmp_int.pl -H 192.168.1.1 -C public -n eth0 -k --label -w 0,0 -c 0,0 -d 15 -MB", "r");
while(fgets(buf, 512, p))
sscanf(buf, "eth0:UP (in=%fMbps/out=%fMbps)", &in, &out);
pclose(p);
printf("in+100: %f out+100: %f\n", in+100, out+100);
}
...but I don't see why you're writing a program to to text processing in C.
If you showed some sample input and the sample output you expected from it, a simple shell script could probably be done for it.