here is my command in bash shell on Mac OS X tiger:

history | tr -d emacs

here is what I get:

hitory | grp "" | tr -d ""
hitory | grp "" | tr -d """"
hitory | grp "" | tr -d ''
hitory | grp "" | tr -d ''
hitory | grp "" | tr -d ''
hitory | grp "" | tr -d ''
hitory | grp "" | tr -d ''
hitory | grp "" | tr -d ''
hitory | grp "" | tr -d ''
hitory | grp "" | tr -d ``
hitory | grp "" | tr -d ""
hitory | grp "" | tr -d ""
hitory | grp "" | tr -d ""
hitory | grp "" | tr -d ""

sadly it removed all ascii characters contained within "emacs", any help appreciated