editing library environment variable --
 

Dear all,
I am installing different version of ns2 in my machine, in different directories under the Home folder. Now that I need to append the library path into bashrc, I am totally confused. I have little idea about it, and saw post about conflicting the environment path and system crash.
My library path is like:
# LD_LIBRARY_PATH
OTCL_LIB=/home/shojaru/ns-allinone-2.28/otcl-1.9
NS2_LIB=/home/shojaru/ns-allinone-2.28/lib
X11_LIB=/usr/X11R6/lib
USR_LOCAL_LIB=/usr/local/lib
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$OTCL_LIB:$NS2_LIB:$X11_LIB:$USR_LOCAL_LIB
# TCL_LIBRARY
TCL_LIB=/home/shojaru/ns-allinone-2.28/tcl8.4.5/library
USR_LIB=/usr/lib
export TCL_LIBRARY=$TCL_LIB:$USR_LIB
# PATH
XGRAPH=/home/shojaru/ns-allinone-2.28/bin:/home/shojaru/ns-allinone-2.28/tcl8.4.5/unix:/home/shojaru/ns-allinone-2.28/tk8.4.5/unix
NS=/home/shojaru/ns-allinone-2.28/ns-2.28/
NAM=/home/shojaru/ns-allinone-2.28/nam-1.11/
PATH=$PATH:$XGRAPH:$NS:$NAM

Now that I will add environment variable for another ns2, should I keep the above one and add another same block by only modifying the path to new ns2? Like:
# LD_LIBRARY_PATH
OTCL_LIB=/home/shojaru/new/ns-allinone-2.29/otcl-1.9
NS2_LIB=/home/shojaru/new/ns-allinone-2.29/lib
X11_LIB=/usr/X11R6/lib
USR_LOCAL_LIB=/usr/local/lib
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$OTCL_LIB:$NS2_LIB:$X11_LIB:$USR_LOCAL_LIB

And keep both the two blocks in the bashrc?

Or, I have to append them in the existing path? Would anyone care to elaborate a little bit on this? Please?

Thank you very much for your kind attention and response :)

I don't use NS2 but I think it depends on how you usually switch things. Try adding this to your ~/.bashrc:
This should give you access to a function called "set_NS2_VER" which, on parsing your .bashrc, will first set a default version, then glean it from ~/.ns2_version if it exists or else if the function is called with an argument like "new", "old", "2.28" or "2.29", then export what's needed. Note your NS2 installs should use same level dir names like "/home/shojaru/ns-allinone-2.28" and "/home/shojaru/ns-allinone-2.29".

Dear unSpawn,
I really cannot find the words to thank you, so much time u spent on writing the codes!!!
I wanted to ask another question. I run ns programs, by going to the specific directory and type in the terminal: ns example.tcl So now,if I edit the ~/.bashrc as above, would it be the same procedure as before? Like:
shojaru@ubuntu:~/ns-allinone-2.28/ns-2.28$ ns example.tcl
shojaru@ubuntu:~/ns-allinone-2.29/ns-2.29$ ns example.tcl
or, I would have to change the procedure ?

Another question is, since I have already installed 2.29 on a different level directory, would it work if I just copy the whole directory into another location?

Thank you very much once again for your kind attention.

Try 'set_NS2_VER old; cd ~/ns-allinone-2.28/ns-2.28; ns example.tcl' or 'set_NS2_VER 2.29; cd ~/ns-allinone-2.29/ns-2.29; ns example.tcl'


I have no idea since I don't use NS2. You could always (make a backup and) try.