Hai,
In slackware, even if I login as "root", the commands like "lsusb","ppp-go","startx" are not responding. If I give "su" then again tried with same commands means, its working.
Am facing this problem recently [ last one week]. Previously, it was straight away worked if I logged in as root. The things happening now are,

root#lsusb
<nothing is coming. same for ppp-go and startx>
root#su
root#lsusb
<it is listing the usb stuffs>

What does "nothing is coming" mean? is it frozen? it just ends with no output?

for "startx", it is trying to initiate the xserver, but it again come back to command line mode with error. [will post error, since now the system is not with me]

I guess, am not getting the root permission even I logging in as root. But, if i give the command "su", it is not prompting for password but thereafter the commands are working fine.

mfillpot wrote:

so your user shell does not know to look into /sbin, /bin, etc.. for commands.

may be. But, I am logging as root. Meanwhile, after "su" command with out asking for password the commands are working.
after "su" , the shell can look into special binaries. But, why its not happening after I logged in as "root".

I will check more with whoami kind of commands, and report it here tonight. [system not with me currently ]

Did you change .bashrc, /etc/profile or any related files prior to the issue?

yes for my device driver programming I added my path in bash_profile. But, I did not remove any thing or changed anything in that file. Just added my path.