I am trying to consolidate my dotfiles so I only have one set for my local OSX machine and Linux servers. I have this conditional statement, but the $(brew --prefix) is running on linux machines even though that block shouldn't run...
SYSTEM=`uname -a | cut -d" " -f1`
# These things are system specific
if [ $SYSTEM=="Darwin" ]; then
    if [ -f $(brew --prefix)/etc/bash_completion ]; then
        . $(brew --prefix)/etc/bash_completion
    fi
    for file in ~/.completion/* ; do
      if [ -f "$file" ] ; then
        . "$file"
      fi
    done
elif [ $SYSTEM=="Linux" ]; then
    alias upgrade='sudo apt-get update && sudo apt-get upgrade'
    # save the IP address in case I need it later
    export IP_ADDRESS=`ifconfig eth0 | grep 'inet addr:' | cut -d: -f2 | awk '{ print $1}'`
fi
if I echo the $SYSTEM variable on the linux machine it says it is Linux but sourcing of the bashrc fails on the brew --prefix command. 
Does it evaluate that variable no matter what? Is there a way I can change it to work?
 
    