System Calls using C w/BASH Post: 302611727

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Top Forums Programming System Calls using C w/BASH Post 302611727 by whyte_rhyno on Friday 23rd of March 2012 11:14:03 AM

03-23-2012

Registered User

Quote:

Originally Posted by Corona688

Your buffer only has five bytes of space.

Writing beyond that is rampaging through stack space, overwriting every local variable behind it until it finds and corrupts your stack frame itself, crashing your program the next time it tries to do anything to the stack.

Code:

#include <stdio.h>
#include <string.h>

int main(int argc, char *argv[])
{
    
    int i;
    char theCommand[16384] = "cat ";
  
    for (i = 1; i < argc; i++)
    {
        strcat(theCommand, argv[i]);
    }
    strcat(theCommand, " >> testfile.txt");
    system(theCommand);

    return 0;
}

D'oh! That would explain the segmentation fault, then.

Thank you very much for your help!

I had to put some white space in between the files because it was concatenating them together like: file.txtfile2.txtfile3.txt, is this the acceptable way of doing it (below)?

Code:

#include <stdio.h>
#include <string.h>

int main(int argc, char *argv[])
{
    
    int i;
    char theCommand[16384] = "cat ";
  
    for (i = 1; i < argc; i++)
    {
        strcat(theCommand, argv[i]);
        strcat(theCommand, " ");
    }
    strcat(theCommand, " >> testfile.txt");
    system(theCommand);

    return 0;
 }

whyte_rhyno

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LEARN ABOUT DEBIAN

sc_warts2text

SC_WARTS2TEXT(1)					    BSD General Commands Manual 					  SC_WARTS2TEXT(1)

NAME

     sc_warts2text -- simple dump of information contained in a warts file.

SYNOPSIS

     sc_warts2text [-d ip2descr-file] [file ...]

DESCRIPTION

     The sc_warts2text utility provides a simple dump of information contained in a sequence of warts files.  The output is the same as that which
     would have been provided by scamper if the text output option had been chosen instead of the warts output option when the data was collected.
     The options are as follows:

     -d ip2descr-file
	     specifies the name of a file with IP-address, description mappings, one mapping per line.	See the examples section for further
	     information.

     While the output of sc_warts2text is structured and suitable for initial analyses of results, the format of the output is not suitable for
     automated parsing and analysis as the output of sc_warts2text will change overtime with no regard to backwards compatibility.  Analyses of
     the contents of a warts file should be made using specialised programs which link against the scamper file API.

EXAMPLES

     The command:

	sc_warts2text file1.warts file2.warts

     will decode and print the contents of file1.warts, followed by the contents of file2.warts.

     The command:

	gzcat file1.warts.gz | sc_warts2text

     will print the contents of the uncompressed file supplied on stdin.

     Given a set of IP-address, description pairs in a file name mappings.txt:

	192.0.2.1 "foo"
	192.0.2.2 "bar"

     then the command gzcat file1.warts.gz | sc_warts2text -d mappings.txt will print the description associated with a given destination address
     before each result is presented.

SEE ALSO

     scamper(1), sc_wartsdump(1)

AUTHORS

     sc_warts2text is written by Matthew Luckie <mjl@luckie.org.nz>.

BSD
								 October 15, 2010							       BSD

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