Ok, i created a test user with the /bin/sh shell instead of /bin/bash, and the command is showing the error.
So 'tr' parameters are not interpreted the same way in bash and sh.
Thanks for pointing that out to me !
PS : the error was in fact harmless, as my wireless card was properly working. The HWADDR var is even not needed for my setup, as im not using the rc.wireless.conf file. Can as well comment the line.
I was just trying to understand & suppress the error message (dont like them).
From a newbie perspective, the wpa_supplicant integration is not as clear as the rc.* scripts are.
I wish the whole WPA thing could be configured from ONLY the rc.wireless/rc.wireless.conf files (so without a wpa_supplicant.conf file). From what I read and understood in AlienBOB's WPA guide, it's not possible. But me noob, so maybe I wasn't getting the whole point. Now I messed a bit more with the files, I'm gonna re-read this guide.
But now I think about it, I read in slack14 changelog (search for "rc.wireless" in http://slackware.com/changelog/current.php?cpu=i386
Perhaps this was the cause of some of the reports of non-functional wireless interfaces?
My 'tr' error MAY be a cause for non-functional wireless devices.
If you use the rc.wireless.conf file for wireless settings, and you dont write them in the generic case ($HWADDR in *), rather in the card-specific blocks ($HWADDR in xx:xx:xx), as the $HWADDR is not set, the script may not find the correct parameters, as never entering any case ?!
My 2 cents.