Add paths to $PATH from multiple places in .bashrc/etc. : http://proccli.com/easy-add-paths-path-bash

push_path.sh

# Push a path to our $PATH variable
# Usage:
#    push_path <path> [after]
# If after is specified it will appear at the end of $PATH, otherwise it is unshifted
push_path(){
        if ! echo $PATH | egrep -q "(^|:)$1($|:)" ; then
           if [ "$2" = "after" ] ; then
              PATH=$PATH:$1
           else
              PATH=$1:$PATH
           fi
        fi
}

usage.sh

# Push all local/**/bin
push_path /usr/local/bin
for path in `ls -d /usr/local/*/bin 2>/dev/null`; do
        push_path $path
done

# Push ~/bin
push_path $HOME/bin

# Push /opt/bin at the end
push_path /opt/bin "after"