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Execute a Shell command silently and get the Output

Posted on 2004-03-26
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Last Modified: 2007-12-19
Hello everyone,

I was looking for a way to execute a shell command (e.g. "ping localhost") without the user seeing a command shell(Win XP)
and recieve its output. Any ideas on that?

Thank you in advance,
Lord.
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Comment
Question by:LordTTSeven
  • 2
4 Comments
 
LVL 8

Expert Comment

by:mnashadka
ID: 10691950
You can use _popen to open the command as a FILE *, and then use the standard fgets/fscanf/etc. functions to read the result, then use _pclose to close the stream.  Hope this helps.
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LVL 23

Expert Comment

by:chensu
ID: 10692764
Call ShellExecute() with the SW_HIDE flag. Or call CreateProcess() with the DETACHED_PROCESS flag.
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Author Comment

by:LordTTSeven
ID: 10694123
chensu:

I honestly dont get it how to recieve the Output here?

mnashadka:

This code:

#include <stdio.h>

void main(void) {
      FILE* cons;
      char s[999];
      cons = _popen("ping localhost","r");
      
      while(fscanf(cons,"%s",s))
            printf("%s",s);
      
      _pclose(cons);
      scanf("%s",s);
}

Provides me this(excuse my german Windows)

C:\User\VC>shellexec
Pinglord2[127.0.0.1]mit32BytesDaten:Antwortvon127.0.0.1:Bytes=32Zeit<1msTTL=128A
ntwortvon127.0.0.1:Bytes=32Zeit<1msTTL=128Antwortvon127.0.0.1:Bytes=32Zeit<1msTT
L=128Antwortvon127.0.0.1:Bytes=32Zeit<1msTTL=128Ping-Statistikfür127.0.0.1:Paket
e:Gesendet=4,Empfangen=4,Verloren=0(0%Verlust),Ca.ZeitangabeninMillisek.:Minimum
=0ms,Maximum=0ms,Mittelwert=0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0
ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms0ms
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It somehow does neither get CRLFs nor Spaces, and the last word(?) is repeatet untill i press CTRL+C...

Thank you, Lord.
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LVL 8

Accepted Solution

by:
mnashadka earned 50 total points
ID: 10695479
fscanf ignores whitespace, and i suggest that the end part is related to the buffer not being cleared out.  Change fscanf to fgets, and you'll get better results:

#include <stdio.h>

void main(void) {
     FILE* cons;
     char s[999];
     cons = _popen("ping localhost","r");
     
     while(fgets(s, 999, cons))
        printf("%s",s);
     
     _pclose(cons);
     scanf("%s",s);
}
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