Thread: Need to pass parameters to system()

So why not just invoke the perl script directly, rather than involving a C program which adds almost no value to your task.

Code:

#include <stdio.h>
#include <stdlib.h>

main( int argc, char *argv[] )
{
    char String[255];

    
    if ( argc == 5)
    {
        sprintf(String, "/usr/local/script/send_pl %s %s %s %s", argv[1], argv[2], argv[3], argv[4]);
        system(String);
    }
    else if ( argc < 5)
    {
        printf("USAGE: sendit <keyname> <local file> <remote file> <speed>\n");
    }
return ;
}

I can't test at the moment, but something like that. I am assuming your command and parameters will never be more then 254 characters.

anonytmouse, I'd change your code into either:

Code:

#include <stdlib.h>
#include <stdio.h>

int main(int argc, char * argv[])
{
    if (argc == 5)
    {
        char cmdLine[4096];
        sprintf(cmdLine, "/usr/local/script/send_it.pl %s %s %s %s",
                           argv[1], argv[2], argv[3], argv[4]);
        return system(cmdLine);
    }
    printf("USAGE: sendit <keyname> <local file> <remote file> <speed>\n");
    return EXIT_FAILURE;
}

No need for the ELSE clause

or

Code:

#include <stdlib.h>
#include <stdio.h>

int main(int argc, char * argv[])
{
    int rtn;
    if (argc == 5)
    {
        char cmdLine[4096];
        sprintf(cmdLine, "/usr/local/script/send_it.pl %s %s %s %s",
                           argv[1], argv[2], argv[3], argv[4]);
        rtn = system(cmdLine);
    }
    else
    {
        printf("USAGE: sendit <keyname> <local file> <remote file> <speed>\n");
        rtn = EXIT_FAILURE;
    }

    return rtn;
}

Use the preferred one-return-per-function format

You might prefer to defer argument checking (other than exceeding the max string length) to send_it.pl. This potentially makes for easier maintenance.

In other words, construct your cmdLine string with ALL the arguments and let send_it.pl decide how to handle them, whether to fail or not and what error message to kick out.

No line length problems at all - if you want to keep the same args

Code:

#include <unistd.h>
int main ( int argc, char *argv[] ) {
  if ( argc == 5 ) {
    argv[0] = "/usr/local/script/send_it.pl";
    execv( argv[0], argv );
  }
}

Originally Posted by nonpuz

why can you assign to argv like that, but normally you would have to use strcpy?

You can't use strcpy() on argv[0], because you have no idea where argv[0] is pointing at, nor how long that memory is. By changing the pointer to point to a new string, you guarantee not to overlay memory you're not supposed to.

I give up. This is the last time I'm commenting on your code.

Code:

sauv=free(*arg[]);

1) There is nothing called sauv in your code.
2) You cannot free argv, and if you could, that would be wrong.
2a) I'll have to assume you were trying to free argv, because there is no arg in your program.

I'm not the boss here. I don't make the rules. However, please, for the sake of all other posters who are trying to learn, compile your code before posting it. Yes, I've typoed and even posted incorrect code before. But I don't do it every single post, all day long. So for the sake of everyone here, compile before you post.

Quzah.