zprofile: introduce zprofile use El Capitan (OS X 10.11) introduces a system-level /etc/zprofile which uses a path_helper thing to mangle $PATH. Unfortunately, the way path_helper works, it forces /usr/local/bin and /usr/bin to the *start* of the PATH variable, which means that any PATH mutations I want have to run after /etc/zprofile calls path_helper. As such, move my path insertions into .zprofile{,-machine} rather than .zshenv{,-machine} so that I can still ensure my path entries are at the start of PATH rather than the end. This works because: > Commands are then read from $ZDOTDIR/.zshenv. If the shell is a > login shell, commands are read from /etc/zprofile and then > $ZDOTDIR/.zprofile. Then, if the shell is interactive, commands > are read from /etc/zshrc and then $ZDOTDIR/.zshrc. Finally, if the > shell is a login shell, /etc/zlogin and $ZDOTDIR/.zlogin are read. This means that non-login shells no longer pick up my custom PATH entries, but as I only use OS X as a desktop OS that seems like a workable tradeoff for now.

# Functions for manipulating $PATH. Split out so I can use them in .zshenv if I want.

function insert_path_element() {
  insert_element_into_var $1 PATH
}

function remove_path_element() {
  remove_element_from_var $1 PATH
}

function insert_element_into_var () {
  eval varcontents=\$"$2"
  eval varname="$2"
  newcomp="$1"
  if echo "$varcontents" | grep "$newcomp:" >> /dev/null; then
    true
  elif [[ "$varcontents" == "" ]] ; then
    export $varname="$newcomp"
  else
    export $varname="$newcomp:$varcontents"
  fi
}

function remove_element_from_var() {
  eval varcontents=\$"$2"
  eval varname="$2"
  newcomp="$1"
  if echo "$varcontents" | grep "$newcomp:" >> /dev/null; then
    export $varname="`echo $varcontents | sed s%$newcomp:%%`"
  elif [[ "$varcontents" == "$newcomp" ]] ; then
    unset $varname
  else
    echo $1 not in $varname
  fi
}