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.
Makefile.am Makefile.in bcmp.c bcopy.c bzero.c index.c memccpy.c memchr.c memcmp.c memcpy.c memmove.c mempcpy.c memset.c rindex.c strcasecmp.c strcat.c strchr.c strcmp.c strcoll.c strcpy.c strcspn.c strdup.c strdup_r.c strerror.c strerror_r.c strings.tex strlcat.c strlcpy.c strlen.c strlwr.c strncasecmp.c strncat.c strncmp.c strncpy.c strndup.c strndup_r.c strnlen.c strpbrk.c strrchr.c strsep.c strspn.c strstr.c strtok.c strtok_r.c strupr.c strxfrm.c swab.c u_strerr.c wcscat.c wcschr.c wcscmp.c wcscoll.c wcscpy.c wcscspn.c wcslcat.c wcslcpy.c wcslen.c wcsncat.c wcsncmp.c wcsncpy.c wcsnlen.c wcspbrk.c wcsrchr.c wcsspn.c wcsstr.c wcstrings.tex wcswidth.c wcwidth.c wmemchr.c wmemcmp.c wmemcpy.c wmemmove.c wmemset.c