Linux install

hi
i am new with linux. i have installed fedora 16 for my application to running ROMS model. in ROMS site has written that: there are one way to provide the location for the NetCDF files (and optional HDF5 library). If you are always going to be using the same compiler on each system, you can edit your .profile or .login files to globally set them. for ksh/bash n following way:

 export NETCDF_INCDIR=/usr/local/netcdf4/include
 export NETCDF_LIBDIR=/usr/local/netcdf4/lib 
export HDF5_LIBDIR=/usr/local/hdf5/lib

at first i did not understand what is ksh/bash but after reading this forum, i' have got that ksh and bash are 2 kinds of shells. and now i have 2 questions:
1-generaly i check /usr/bin/ directory. there are bash and zsh and sh's shourtcut. hence my system has 3 shells?and i can use 3 of them?
2 -with regard your experience, where i must put following commands:

export NETCDF_INCDIR=/usr/local/netcdf4/include
 export NETCDF_LIBDIR=/usr/local/netcdf4/lib 
export HDF5_LIBDIR=/usr/local/hdf5/lib

thanks in advance
sincerely yours
fereshte

fedora uses the bash shell by default. You can verify which shell you logged in by executing echo $SHELL . Also, you can verify the default shell by looking at the last field (7th field between `:') in /etc/passwd for the specific user.

/etc/profile is where every shell looks at login, however this file affects the system globally, i.e every user. That's why there are other files in each user home that can over write these settings and modify the specific shell environment. For bash, after executing /etc/profile it looks for ~/.bash_profile , ~/.bash_login , and ~/.profile , in that order, and execute from only the first one that exist and the permission is set to read.