Shell Programming and Scripting

#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdio.h>
int main()
{
int exitcode;
char *buf="/var/tmp/bin/em_validation";
char *buf1="grep madhu x";
char *buf2="grep ding x";
char *buf3="ls";
char *buf4="ls > output";

exitcode=system((const char*)buf);
if ((exitcode != -1) && WIFEXITED(exitcode))
     exitcode = WEXITSTATUS(exitcode);
printf("\ncommand not found = %d\n",exitcode);

exitcode=system((const char*)buf1);
if ((exitcode != -1) && WIFEXITED(exitcode))
     exitcode = WEXITSTATUS(exitcode);
printf("\ngrep no output = %d\n",exitcode);

exitcode=system((const char*)buf2);
if ((exitcode != -1) && WIFEXITED(exitcode))
     exitcode = WEXITSTATUS(exitcode);
printf("\ngrep with output = %d\n",exitcode);

exitcode=system((const char*)buf3);
if ((exitcode != -1) && WIFEXITED(exitcode))
     exitcode = WEXITSTATUS(exitcode);
printf("\nsuccessful command ls  = %d\n",exitcode);

exitcode=system((const char*)buf4);
if ((exitcode != -1) && WIFEXITED(exitcode))
     exitcode = WEXITSTATUS(exitcode);
printf("\nsuccessful command with no output ls > outputfile  = %d\n",exitcode);



return exitcode;
}

RETURN VALUES
     The system() function executes vfork(2) to  create  a  child
     process that in turn invokes one of the exec family of func-
     tions (see exec(2)) on  the  shell  to  execute  string.  If
     vfork()  or the exec function fails, system() returns -1 and
     sets errno to indicate the error.

RETURN VALUES
     The system() function executes posix_spawn(3C) to  create  a
     child  process  running  the shell that in turn executes the
     commands in string. If posix_spawn() fails, system() returns
     -1  and sets errno to indicate the error; otherwise the exit
     status of the shell is returned.