I'm also facing the same problem while running ns in Ubuntu......

Usage: host [-v] [-a] [-t querytype] [options] name [server]
Listing: host [-v] [-a] [-t querytype] [options] -l zone [server]
Hostcount: host [-v] [options] -H [-D] [-E] [-G] zone
Check soa: host [-v] [options] -C zone
Addrcheck: host [-v] [options] -A host
Listing options: [-L level] [-S] [-A] [-p] [-P prefserver] [-N skipzone]
Common options: [-d] [-f|-F file] [-I chars] [-i|-n] [-q] [-Q] [-T] [-Z]
Other options: [-c class] [-e] [-m] [-o] [-r] [-R] [-s secs] [-u] [-w]
Special options: [-O srcaddr] [-j minport] [-J maxport]
Extended usage: [-x [name ...]] server [name ...]]


I edit the path (bashrc) with the following lines:

# LD_LIBRARY_PATH
OTCL_LIB=/home/user/ns-allinone-2.33/otcl-1.13
NS2_LIB=/home/user/ns-allinone-2.33/lib
X11_LIB=/usr/X11R6/lib
USR_LOCAL_LIB=/usr/local/lib
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$OTCL_LIB:$NS2_LI B
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$X11_LIB:$USR_LOC AL_LIB

# TCL_LIBRARY
TCL_LIB=/home/user/ns-allinone-2.33/tcl8.4.18/library
USR_LIB=/usr/lib
export TCL_LIBRARY=$TCL_LIB:$USR_LIB

# PATH
XGRAPH=/home/user/ns-allinone-2.33/bin
XGRAPH=$XGRAPH:/home/user/ns-allinone-2.33/tcl8.4.18/unix
XGRAPH=$XGRAPH:/home/user/ns-allinone-2.33/tk8.4.18/unix
NS=/home/user/ns-allinone-2.33/ns-2.33/
NAM=/home/user/ns-allinone-2.33/nam-1.13/
PATH=$PATH:$XGRAPH:$NS:$NAM

PLz help me.....