execute and receive the output of mml command in c++

Question

i have an interface where i use to execute the mml command in my solaris unix like below:

> eaw 0004
<RLTYP; 
BSC SYSTEM TYPE DATA

GSYSTYPE
GSM1800

END
<

As soon as i do eaw <name> on the command line.It will start an interface where in i can execute mml commands and i can see the output of those commands executed.

My idea here is to parse the command output in c++. I can do away with some logic for parsing.But to start with How can get the command to be executed inside c++ ? Is there any predefined way to do this. This should be similar to executing sql queries inside c++.But we use other libraries to execute sql queries.I also donot want to run a shell script or create temporary files in between.

what i want is to execute the command inside c++ and get the output and even that in c++. could anybody give me the right directions?

Answer 1

You have several options. From easiest and simplest to hardest and most complex to use:

• Use the system() call to spawn a shell to run a command
• Use the popen() call to spawn a subprocess and either write to its standard input stream or read from its standard output stream (but not both)
• Use a combination of pipe() , fork() , dup() / dup2() , and exec*() to spawn a child process and set up pipes for a child process's standard input and output.

Answer 2

The below code is done with the sh command. This redirects stdout to a file named "out" which can be read later to process the output. Each command to the process can be written through the pipe.

#include <stdio.h>
int main()
{
        FILE *fp;
        fp = popen("sh > out", "w");
        if (fp) {
                fprintf(fp, "date\n");
                fprintf(fp, "exit\n");
                fclose(fp);
        }
        return 0;
}