I know many people have asked about environment variables before, but I am having a hard time dealing with these paths while ensuring I don't mess around with the original settings. How would you go about executing these commands in Ubuntu in terms of environment variables? Thanks in advance!

Please put /home/stanley/Downloads/ns-allinone-2.34/bin:/home/stanley/Downloads/ns-allinone-2.34/tcl8.4.18/unix:/home/stanley/Downloads/ns-allinone-2.34/tk8.4.18/unix into your PATH environment; so that you'll be able to run itm/tclsh/wish/xgraph.

IMPORTANT NOTICES:

(1) You MUST put /home/stanley/Downloads/ns-allinone-2.34/otcl-1.13, /home/stanley/Downloads/ns-allinone-2.34/lib, into your LD_LIBRARY_PATH environment variable. If it complains about X libraries, add path to your X libraries into LD_LIBRARY_PATH. If you are using csh, you can set it like: setenv LD_LIBRARY_PATH If you are using sh, you can set it like: export LD_LIBRARY_PATH=

(2) You MUST put /home/stanley/Downloads/ns-allinone-2.34/tcl8.4.18/library into your TCL_LIBRARY environmental variable. Otherwise ns/nam will complain during startup.