#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <pwd.h>

main() {
 struct passwd *pwd;
 size_t len = 200;
 char cmd[len];
 char *fqdn = "tuna.tenchi.ne.jp";

 pwd = getpwuid(getuid());
 printf("SMTP AUTH password for user %s\n",pwd->pw_name);
 snprintf(cmd,len,"saslpasswd -u %s %s",fqdn,pwd->pw_name);
 system(cmd);
}