GDB, the GNU Project debugger, allows you to see what is going on `inside' another program while it executes -- or what another program was doing at the moment it crashed.
machine/ _types.h ansi.h endian.h fastmath.h ieeefp.h malloc.h param.h setjmp-dj.h setjmp.h stdlib.h termios.h time.h types.h sys/ _types.h cdefs.h config.h dirent.h errno.h fcntl.h features.h file.h iconvnls.h lock.h param.h queue.h reent.h resource.h sched.h signal.h stat.h stdio.h string.h syslimits.h time.h timeb.h times.h types.h unistd.h utime.h wait.h _ansi.h _syslist.h alloca.h ar.h argz.h assert.h ctype.h dirent.h envz.h errno.h fastmath.h fcntl.h getopt.h grp.h iconv.h ieeefp.h inttypes.h langinfo.h libgen.h limits.h locale.h malloc.h math.h newlib.h paths.h process.h pthread.h pwd.h reent.h regdef.h search.h setjmp.h signal.h stdint.h stdio.h stdlib.h string.h termios.h time.h unctrl.h unistd.h utime.h utmp.h wchar.h wctype.h