1. These 2 are almost the same:

   
   
   

   export PATH=/usr/share/lib/something:$PATH 
   
   export PATH=$PATH:/usr/share/lib/something
   
   

   
   
   

   The only difference is that the first one puts the directory to add in front and the second one puts it behind the current directories in $PATH. It only matters if there are commands inside /usr/share/lib/something that have the same name inside one of the directories in $PATH.




2. To add directories to $MANPATH or $INFOPATH as required from the link you posted you do that by changing the config files inside the link.

   
   
   

   It says to open the global version of bash.bashrc with:

   
   
   

   sudo vi /etc/bash.bashrc
   
   

   
   
   

   and to add at the end:

   
   
   

   PATH=/usr/local/texlive/2010/bin/x86_64-linux:$PATH; export PATH
   
   MANPATH=/usr/local/texlive/2010/texmf/doc/man:$MANPATH; export MANPATH
   
   INFOPATH=/usr/local/texlive/2010/texmf/doc/info:$INFOPATH; export INFOPATH
   
   

   
   
   

   This sets $PATH, $MANPATH and $INFOPATH. And it also tells you to edit /etc/manpath.config with:

   
   
   

   sudo vi /etc/manpath.config
   
   

   
   
   

   and to add

   
   
   

   MANPATH_MAP /usr/local/texlive/2010/bin/x86_64-linux /usr/local/texlive/2010/texmf/doc/man
   
   

   
   
   

   underneath # set up PATH to MANPATH mapping.

If you are unsure about this make a backup 1st (never a bad thing) with:

sudo cp /etc/bash.bashrc /etc/bash.backup_$(date +"%Y_%m_%d").bashrc

sudo cp /etc/manpath.config /etc/manpath.backup_$(date +"%Y_%m_%d").config

The weird string changes into the current date. If you mess up just copy the backup back over the original file:

$ touch test1

$ cp test1 test1.$(date +"%Y_%m_%d")

$ ls

test1  test1.2014_11_14