sudo
gedit ~/.bashrc
export PATH=$PATH:/usr/local/src/ns-allinone-2.30/bin:/usr/local/src/ns-allinone-2.30/tcl8.4.13/unix:/usr/local/src/ns-allinone-2.30/tk8.4.13/unix
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/src/ns-allinone-2.30/otcl-1.12:/usr/local/src/ns-allinone-2.30/lib
export TCL_LIBRATY=$TCL_LIBRATY:/usr/local/src/ns-allinone-2.30/tcl8.4.13/library