xv6-riscv-kernel/user/echo.c

#include "kernel/types.h"
#include "kernel/stat.h"
#include "user/user.h"

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

  for(i = 1; i < argc; i++)
    printf("%s%s", argv[i], i+1 < argc ? " " : "\n");
  exit();
}