I am desperate!
I tried to upgrade my 8.1 version of Slack to 9.0, everything was going on fine till I got that message when it came to upgrade the bin package:

"removepkg: line 273 sed command not found
removepkg: line 1 sed command not found"

PLEASE HELP ME!

PS I followed exactly the manual on the cd concerning the upgrade proccess
(1st upgrade the glibs-solibs, then pkgtool and then everything else....

My UPGRADE.TXT file has a step 3:
===========================================
3. Install sed. This is used by the package utilities.

installpkg /root/slackware/a/sed-*.tgz
===========================================
You didn't mention this step and it would appear to apply to your problem.

It interesting here to also note that my copy of the UPGRADE.TXT file was downloaded via rsync shortly after release from the slackware-cuurent and the file is dated 19 March. On my boxed 9.0 set, the UPGRADE.TXT file is dated 17 March and it does not have the sed packages as step number three. So I have to conclude that this was a bug in the procedures that was not discovered until just after the offical release of 9.0 and was too late to change the CD images.

go to 8.1 tree
find MANIFEST file
,see which package has 'sed'
and install it.

hope it helps