diff --git a/zsh/files.d/aliases.zsh b/zsh/files.d/aliases.zsh
new file mode 100644
index 0000000..9870538
--- /dev/null
+++ b/zsh/files.d/aliases.zsh
@@ -0,0 +1,36 @@
+# Changing/making/removing directory
+setopt auto_pushd
+setopt pushd_ignore_dups
+setopt pushdminus
+
+# Command Line Foo
+alias clf='clf --color'
+
+# The Fuck
+TF_ALIAS=fuck alias fuck='eval $(thefuck $(fc -ln -1 | tail -n 1)); fc -R'
+
+# PClear
+pclear () {
+    clear
+    printf '\033[3J'
+}
+
+# Termbin
+alias tb='nc termbin.com 9999'
+
+# Make Dir and enter it
+mkcd() {
+  mkdir $1 &>/dev/null
+  [ -e $1 ] && cd $1
+}
+
+# Listing
+alias la='ls -lah'
+alias ls='ls -lah'
+
+# Interactive
+alias rm='rm -i'
+alias cp='cp -i'
+alias mv='mv -i'
+
+alias psgrep='ps aux | grep -v grep | grep'
diff --git a/zsh/files.d/os/arch-aliases.zsh b/zsh/files.d/os/arch-aliases.zsh
new file mode 100644
index 0000000..5eda274
--- /dev/null
+++ b/zsh/files.d/os/arch-aliases.zsh
@@ -0,0 +1,54 @@
+if (( $+commands[yaourt] )); then
+  alias yaupg='yaourt -Syua'
+  alias yain='yaourt -S'
+  alias yains='yaourt -U'
+  alias yare='yaourt -R'
+  alias yarem='yaourt -Rns'
+fi
+
+alias pacupg='sudo pacman -Syu'
+alias pacin='sudo pacman -S'
+alias pacins='sudo pacman -U'
+alias pacre='sudo pacman -R'
+alias pacrem='sudo pacman -Rns'
+
+paclist() {
+  # Source: https://bbs.archlinux.org/viewtopic.php?id=93683
+  LC_ALL=C pacman -Qei $(pacman -Qu | cut -d " " -f 1) | \
+    awk 'BEGIN {FS=":"} /^Name/{printf("\033[1;36m%s\033[1;37m", $2)} /^Description/{print $2}'
+}
+
+pacdisowned() {
+  emulate -L zsh
+
+  tmp=${TMPDIR-/tmp}/pacman-disowned-$UID-$$
+  db=$tmp/db
+  fs=$tmp/fs
+
+  mkdir "$tmp"
+  trap  'rm -rf "$tmp"' EXIT
+
+  pacman -Qlq | sort -u > "$db"
+
+  find /bin /etc /lib /sbin /usr ! -name lost+found \
+    \( -type d -printf '%p/\n' -o -print \) | sort > "$fs"
+
+  comm -23 "$fs" "$db"
+}
+
+pacmanallkeys() {
+  emulate -L zsh
+  curl -s https://www.archlinux.org/people/{developers,trustedusers}/ | \
+    awk -F\" '(/pgp.mit.edu/) { sub(/.*search=0x/,""); print $1}' | \
+    xargs sudo pacman-key --recv-keys
+}
+
+pacmansignkeys() {
+  emulate -L zsh
+  for key in $*; do
+    sudo pacman-key --recv-keys $key
+    sudo pacman-key --lsign-key $key
+    printf 'trust\n3\n' | sudo gpg --homedir /etc/pacman.d/gnupg \
+      --no-permission-warning --command-fd 0 --edit-key $key
+  done
+}
diff --git a/zsh/files.d/os/deb-aliases.zsh b/zsh/files.d/os/deb-aliases.zsh
new file mode 100644
index 0000000..0f99d0c
--- /dev/null
+++ b/zsh/files.d/os/deb-aliases.zsh
@@ -0,0 +1,219 @@
+# Use aptitude if installed, or apt-get if not.
+# You can just set apt_pref='apt-get' to override it.
+if [[ -e $( which -p aptitude 2>&1 ) ]]; then
+    apt_pref='aptitude'
+    apt_upgr='safe-upgrade'
+else
+    apt_pref='apt-get'
+    apt_upgr='upgrade'
+fi
+
+# Use sudo by default if it's installed
+if [[ -e $( which -p sudo 2>&1 ) ]]; then
+    use_sudo=1
+fi
+
+# Aliases ###################################################################
+# These are for more obscure uses of apt-get and aptitude that aren't covered
+# below.
+alias age='apt-get'
+alias api='aptitude'
+
+# Some self-explanatory aliases
+alias acs="apt-cache search"
+alias aps='aptitude search'
+alias as="aptitude -F \"* %p -> %d \n(%v/%V)\" \
+		--no-gui --disable-columns search"	# search package
+
+# apt-file
+alias afs='apt-file search --regexp'
+
+
+# These are apt-get only
+alias asrc='apt-get source'
+alias app='apt-cache policy'
+
+# superuser operations ######################################################
+if [[ $use_sudo -eq 1 ]]; then
+# commands using sudo #######
+    alias aac='sudo $apt_pref autoclean'
+    alias abd='sudo $apt_pref build-dep'
+    alias ac='sudo $apt_pref clean'
+    alias ad='sudo $apt_pref update'
+    alias adg='sudo $apt_pref update && sudo $apt_pref $apt_upgr'
+    alias adu='sudo $apt_pref update && sudo $apt_pref dist-upgrade'
+    alias afu='sudo apt-file update'
+    alias ag='sudo $apt_pref $apt_upgr'
+    alias ai='sudo $apt_pref install'
+    # Install all packages given on the command line while using only the first word of each line:
+    # acs ... | ail
+    alias ail="sed -e 's/  */ /g' -e 's/ *//' | cut -s -d ' ' -f 1 | "' xargs sudo $apt_pref install'
+    alias ap='sudo $apt_pref purge'
+    alias ar='sudo $apt_pref remove'
+
+    # apt-get only
+    alias ads='sudo apt-get dselect-upgrade'
+
+    # Install all .deb files in the current directory.
+    # Warning: you will need to put the glob in single quotes if you use:
+    # glob_subst
+    alias dia='sudo dpkg -i ./*.deb'
+    alias di='sudo dpkg -i'
+
+    # Remove ALL kernel images and headers EXCEPT the one in use
+    alias kclean='sudo aptitude remove -P ?and(~i~nlinux-(ima|hea) \
+        ?not(~n`uname -r`))'
+
+
+# commands using su #########
+else
+    alias aac='su -ls \'$apt_pref autoclean\' root'
+    abd() {
+        cmd="su -lc '$apt_pref build-dep $@' root"
+        print "$cmd"
+        eval "$cmd"
+    }
+    alias ac='su -ls \'$apt_pref clean\' root'
+    alias ad='su -lc \'$apt_pref update\' root'
+    alias adg='su -lc \'$apt_pref update && aptitude $apt_upgr\' root'
+    alias adu='su -lc \'$apt_pref update && aptitude dist-upgrade\' root'
+    alias afu='su -lc "apt-file update"'
+    alias ag='su -lc \'$apt_pref $apt_upgr\' root'
+    ai() {
+        cmd="su -lc 'aptitude -P install $@' root"
+        print "$cmd"
+        eval "$cmd"
+    }
+    ap() {
+        cmd="su -lc '$apt_pref -P purge $@' root"
+        print "$cmd"
+        eval "$cmd"
+    }
+    ar() {
+        cmd="su -lc '$apt_pref -P remove $@' root"
+        print "$cmd"
+        eval "$cmd"
+    }
+    # Install all .deb files in the current directory
+    # Assumes glob_subst is off
+    alias dia='su -lc "dpkg -i ./*.deb" root'
+    alias di='su -lc "dpkg -i" root'
+    # Remove ALL kernel images and headers EXCEPT the one in use
+    alias kclean='su -lc '\''aptitude remove -P ?and(~i~nlinux-(ima|hea) \
+        ?not(~n`uname -r`))'\'' root'
+fi
+
+# Completion ################################################################
+
+#
+# Registers a compdef for $1 that calls $apt_pref with the commands $2
+# To do that it creates a new completion function called _apt_pref_$2
+#
+apt_pref_compdef() {
+    local f fb
+    f="_apt_pref_${2}"
+
+    eval "function ${f}() {
+        shift words; 
+	service=\"\$apt_pref\"; 
+	words=(\"\$apt_pref\" '$2' \$words); 
+	((CURRENT++))
+	test \"\${apt_pref}\" = 'aptitude' && _aptitude || _apt
+    }"
+
+    compdef "$f" "$1"
+}
+
+apt_pref_compdef aac "autoclean"
+apt_pref_compdef abd "build-dep"
+apt_pref_compdef ac  "clean"
+apt_pref_compdef ad  "update"
+apt_pref_compdef afu "update"
+apt_pref_compdef ag  "$apt_upgr"
+apt_pref_compdef ai  "install"
+apt_pref_compdef ail "install"
+apt_pref_compdef ap  "purge"
+apt_pref_compdef ar  "remove"
+apt_pref_compdef ads "dselect-upgrade"
+
+# Misc. #####################################################################
+# print all installed packages
+alias allpkgs='aptitude search -F "%p" --disable-columns ~i'
+
+# Create a basic .deb package
+alias mydeb='time dpkg-buildpackage -rfakeroot -us -uc'
+
+
+# Functions #################################################################
+# create a simple script that can be used to 'duplicate' a system
+apt-copy() {
+    print '#!/bin/sh'"\n" > apt-copy.sh
+
+    cmd='$apt_pref install'
+
+    for p in ${(f)"$(aptitude search -F "%p" --disable-columns \~i)"}; {
+        cmd="${cmd} ${p}"
+    }
+
+    print $cmd "\n" >> apt-copy.sh
+
+    chmod +x apt-copy.sh
+}
+
+# Prints apt history
+# Usage:
+#   apt-history install
+#   apt-history upgrade
+#   apt-history remove
+#   apt-history rollback
+#   apt-history list
+# Based On: http://linuxcommando.blogspot.com/2008/08/how-to-show-apt-log-history.html
+apt-history () {
+  case "$1" in
+    install)
+      zgrep --no-filename 'install ' $(ls -rt /var/log/dpkg*)
+      ;;
+    upgrade|remove)
+      zgrep --no-filename $1 $(ls -rt /var/log/dpkg*)
+      ;;
+    rollback)
+      zgrep --no-filename upgrade $(ls -rt /var/log/dpkg*) | \
+        grep "$2" -A10000000 | \
+        grep "$3" -B10000000 | \
+        awk '{print $4"="$5}'
+      ;;
+    list)
+      zgrep --no-filename '' $(ls -rt /var/log/dpkg*)
+      ;;
+    *)
+      echo "Parameters:"
+      echo " install - Lists all packages that have been installed."
+      echo " upgrade - Lists all packages that have been upgraded."
+      echo " remove - Lists all packages that have been removed."
+      echo " rollback - Lists rollback information."
+      echo " list - Lists all contains of dpkg logs."
+      ;;
+  esac
+}
+
+# Kernel-package building shortcut
+kerndeb () {
+    # temporarily unset MAKEFLAGS ( '-j3' will fail )
+    MAKEFLAGS=$( print - $MAKEFLAGS | perl -pe 's/-j\s*[\d]+//g' )
+    print '$MAKEFLAGS set to '"'$MAKEFLAGS'"
+	appendage='-custom' # this shows up in $ (uname -r )
+    revision=$(date +"%Y%m%d") # this shows up in the .deb file name
+
+    make-kpkg clean
+
+    time fakeroot make-kpkg --append-to-version "$appendage" --revision \
+        "$revision" kernel_image kernel_headers
+}
+
+# List packages by size
+function apt-list-packages {
+    dpkg-query -W --showformat='${Installed-Size} ${Package} ${Status}\n' | \
+    grep -v deinstall | \
+    sort -n | \
+    awk '{print $1" "$2}'
+}
diff --git a/zsh/files.d/systemd.zsh b/zsh/files.d/systemd.zsh
new file mode 100644
index 0000000..299ac6b
--- /dev/null
+++ b/zsh/files.d/systemd.zsh
@@ -0,0 +1,12 @@
+user_commands=(
+  list-units is-active status show help list-unit-files
+  is-enabled list-jobs show-environment cat list-timers)
+
+sudo_commands=(
+  start stop reload restart try-restart isolate kill
+  reset-failed enable disable reenable preset mask unmask
+  link load cancel set-environment unset-environment
+  edit daemon-reload)
+
+for c in $user_commands; do; alias sc-$c="systemctl $c"; done
+for c in $sudo_commands; do; alias sc-$c="sudo systemctl $c"; done
diff --git a/zsh/single-files/command-history.zsh b/zsh/single-files/command-history.zsh
new file mode 100644
index 0000000..c61c420
--- /dev/null
+++ b/zsh/single-files/command-history.zsh
@@ -0,0 +1,759 @@
+#!/usr/bin/env zsh
+##############################################################################
+#
+# Copyright (c) 2009 Peter Stephenson
+# Copyright (c) 2011 Guido van Steen
+# Copyright (c) 2011 Suraj N. Kurapati
+# Copyright (c) 2011 Sorin Ionescu
+# Copyright (c) 2011 Vincent Guerci
+# Copyright (c) 2016 Geza Lore
+# Copyright (c) 2017 Bengt Brodersen
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+#  * Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+#
+#  * Redistributions in binary form must reproduce the above
+#    copyright notice, this list of conditions and the following
+#    disclaimer in the documentation and/or other materials provided
+#    with the distribution.
+#
+#  * Neither the name of the FIZSH nor the names of its contributors
+#    may be used to endorse or promote products derived from this
+#    software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+##############################################################################
+
+#-----------------------------------------------------------------------------
+# declare global configuration variables
+#-----------------------------------------------------------------------------
+
+typeset -g HISTORY_SUBSTRING_SEARCH_HIGHLIGHT_FOUND='bg=magenta,fg=white,bold'
+typeset -g HISTORY_SUBSTRING_SEARCH_HIGHLIGHT_NOT_FOUND='bg=red,fg=white,bold'
+typeset -g HISTORY_SUBSTRING_SEARCH_GLOBBING_FLAGS='i'
+typeset -g HISTORY_SUBSTRING_SEARCH_ENSURE_UNIQUE=''
+typeset -g HISTORY_SUBSTRING_SEARCH_FUZZY=''
+
+#-----------------------------------------------------------------------------
+# declare internal global variables
+#-----------------------------------------------------------------------------
+
+typeset -g BUFFER MATCH MBEGIN MEND CURSOR
+typeset -g _history_substring_search_refresh_display
+typeset -g _history_substring_search_query_highlight
+typeset -g _history_substring_search_result
+typeset -g _history_substring_search_query
+typeset -g -a _history_substring_search_query_parts
+typeset -g -a _history_substring_search_raw_matches
+typeset -g -i _history_substring_search_raw_match_index
+typeset -g -a _history_substring_search_matches
+typeset -g -i _history_substring_search_match_index
+typeset -g -A _history_substring_search_unique_filter
+
+#-----------------------------------------------------------------------------
+# the main ZLE widgets
+#-----------------------------------------------------------------------------
+
+history-substring-search-up() {
+  _history-substring-search-begin
+
+  _history-substring-search-up-history ||
+  _history-substring-search-up-buffer ||
+  _history-substring-search-up-search
+
+  _history-substring-search-end
+}
+
+history-substring-search-down() {
+  _history-substring-search-begin
+
+  _history-substring-search-down-history ||
+  _history-substring-search-down-buffer ||
+  _history-substring-search-down-search
+
+  _history-substring-search-end
+}
+
+zle -N history-substring-search-up
+zle -N history-substring-search-down
+
+#-----------------------------------------------------------------------------
+# implementation details
+#-----------------------------------------------------------------------------
+
+zmodload -F zsh/parameter
+
+#
+# We have to "override" some keys and widgets if the
+# zsh-syntax-highlighting plugin has not been loaded:
+#
+# https://github.com/nicoulaj/zsh-syntax-highlighting
+#
+if [[ $+functions[_zsh_highlight] -eq 0 ]]; then
+  #
+  # Dummy implementation of _zsh_highlight() that
+  # simply removes any existing highlights when the
+  # user inserts printable characters into $BUFFER.
+  #
+  _zsh_highlight() {
+    if [[ $KEYS == [[:print:]] ]]; then
+      region_highlight=()
+    fi
+  }
+
+  #
+  # The following snippet was taken from the zsh-syntax-highlighting project:
+  #
+  # https://github.com/zsh-users/zsh-syntax-highlighting/blob/56b134f5d62ae3d4e66c7f52bd0cc2595f9b305b/zsh-syntax-highlighting.zsh#L126-161
+  #
+  # Copyright (c) 2010-2011 zsh-syntax-highlighting contributors
+  # All rights reserved.
+  #
+  # Redistribution and use in source and binary forms, with or without
+  # modification, are permitted provided that the following conditions are
+  # met:
+  #
+  #  * Redistributions of source code must retain the above copyright
+  #    notice, this list of conditions and the following disclaimer.
+  #
+  #  * Redistributions in binary form must reproduce the above copyright
+  #    notice, this list of conditions and the following disclaimer in the
+  #    documentation and/or other materials provided with the distribution.
+  #
+  #  * Neither the name of the zsh-syntax-highlighting contributors nor the
+  #    names of its contributors may be used to endorse or promote products
+  #    derived from this software without specific prior written permission.
+  #
+  # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+  # IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+  # THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+  # PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+  # CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+  # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+  # PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+  # PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+  # LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+  # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+  # SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+  #
+  #--------------8<-------------------8<-------------------8<-----------------
+  # Rebind all ZLE widgets to make them invoke _zsh_highlights.
+  _zsh_highlight_bind_widgets()
+  {
+    # Load ZSH module zsh/zleparameter, needed to override user defined widgets.
+    zmodload zsh/zleparameter 2>/dev/null || {
+      echo 'zsh-syntax-highlighting: failed loading zsh/zleparameter.' >&2
+      return 1
+    }
+
+    # Override ZLE widgets to make them invoke _zsh_highlight.
+    local cur_widget
+    for cur_widget in ${${(f)"$(builtin zle -la)"}:#(.*|_*|orig-*|run-help|which-command|beep|yank*)}; do
+      case $widgets[$cur_widget] in
+
+        # Already rebound event: do nothing.
+        user:$cur_widget|user:_zsh_highlight_widget_*);;
+
+        # User defined widget: override and rebind old one with prefix "orig-".
+        user:*) eval "zle -N orig-$cur_widget ${widgets[$cur_widget]#*:}; \
+                      _zsh_highlight_widget_$cur_widget() { builtin zle orig-$cur_widget -- \"\$@\" && _zsh_highlight }; \
+                      zle -N $cur_widget _zsh_highlight_widget_$cur_widget";;
+
+        # Completion widget: override and rebind old one with prefix "orig-".
+        completion:*) eval "zle -C orig-$cur_widget ${${widgets[$cur_widget]#*:}/:/ }; \
+                            _zsh_highlight_widget_$cur_widget() { builtin zle orig-$cur_widget -- \"\$@\" && _zsh_highlight }; \
+                            zle -N $cur_widget _zsh_highlight_widget_$cur_widget";;
+
+        # Builtin widget: override and make it call the builtin ".widget".
+        builtin) eval "_zsh_highlight_widget_$cur_widget() { builtin zle .$cur_widget -- \"\$@\" && _zsh_highlight }; \
+                       zle -N $cur_widget _zsh_highlight_widget_$cur_widget";;
+
+        # Default: unhandled case.
+        *) echo "zsh-syntax-highlighting: unhandled ZLE widget '$cur_widget'" >&2 ;;
+      esac
+    done
+  }
+  #-------------->8------------------->8------------------->8-----------------
+
+  _zsh_highlight_bind_widgets
+fi
+
+_history-substring-search-begin() {
+  setopt localoptions extendedglob
+
+  _history_substring_search_refresh_display=
+  _history_substring_search_query_highlight=
+
+  #
+  # If the buffer is the same as the previously displayed history substring
+  # search result, then just keep stepping through the match list. Otherwise
+  # start a new search.
+  #
+  if [[ -n $BUFFER && $BUFFER == ${_history_substring_search_result:-} ]]; then
+    return;
+  fi
+
+  #
+  # Clear the previous result.
+  #
+  _history_substring_search_result=''
+
+  if [[ -z $BUFFER ]]; then
+    #
+    # If the buffer is empty, we will just act like up-history/down-history
+    # in ZSH, so we do not need to actually search the history. This should
+    # speed things up a little.
+    #
+    _history_substring_search_query=
+    _history_substring_search_query_parts=()
+    _history_substring_search_raw_matches=()
+
+  else
+    #
+    # For the purpose of highlighting we keep a copy of the original
+    # query string.
+    #
+    _history_substring_search_query=$BUFFER
+
+    #
+    # compose search pattern
+    #
+    if [[ -n $HISTORY_SUBSTRING_SEARCH_FUZZY ]]; then
+      #
+      # `=` split string in arguments
+      #
+      _history_substring_search_query_parts=(${=_history_substring_search_query})
+    else
+      _history_substring_search_query_parts=(${_history_substring_search_query})
+    fi
+
+    #
+    # Escape and join query parts with wildcard character '*' as seperator
+    # `(j:CHAR:)` join array to string with CHAR as seperator
+    #
+    local search_pattern="*${(j:*:)_history_substring_search_query_parts[@]//(#m)[\][()|\\*?#<>~^]/\\$MATCH}*"
+
+    #
+    # Find all occurrences of the search pattern in the history file.
+    #
+    # (k) returns the "keys" (history index numbers) instead of the values
+    # (R) returns values in reverse older, so the index of the youngest
+    # matching history entry is at the head of the list.
+    #
+    _history_substring_search_raw_matches=(${(k)history[(R)(#$HISTORY_SUBSTRING_SEARCH_GLOBBING_FLAGS)${search_pattern}]})
+  fi
+
+  #
+  # In order to stay as responsive as possible, we will process the raw
+  # matches lazily (when the user requests the next match) to choose items
+  # that need to be displayed to the user.
+  # _history_substring_search_raw_match_index holds the index of the last
+  # unprocessed entry in _history_substring_search_raw_matches. Any items
+  # that need to be displayed will be added to
+  # _history_substring_search_matches.
+  #
+  # We use an associative array (_history_substring_search_unique_filter) as
+  # a 'set' data structure to ensure uniqueness of the results if desired.
+  # If an entry (key) is in the set (non-empty value), then we have already
+  # added that entry to _history_substring_search_matches.
+  #
+  _history_substring_search_raw_match_index=0
+  _history_substring_search_matches=()
+  _history_substring_search_unique_filter=()
+
+  #
+  # If $_history_substring_search_match_index is equal to
+  # $#_history_substring_search_matches + 1, this indicates that we
+  # are beyond the end of $_history_substring_search_matches and that we
+  # have also processed all entries in
+  # _history_substring_search_raw_matches.
+  #
+  # If $#_history_substring_search_match_index is equal to 0, this indicates
+  # that we are beyond the beginning of $_history_substring_search_matches.
+  #
+  # If we have initially pressed "up" we have to initialize
+  # $_history_substring_search_match_index to 0 so that it will be
+  # incremented to 1.
+  #
+  # If we have initially pressed "down" we have to initialize
+  # $_history_substring_search_match_index to 1 so that it will be
+  # decremented to 0.
+  #
+  if [[ $WIDGET == history-substring-search-down ]]; then
+     _history_substring_search_match_index=1
+  else
+    _history_substring_search_match_index=0
+  fi
+}
+
+_history-substring-search-end() {
+  setopt localoptions extendedglob
+
+  _history_substring_search_result=$BUFFER
+
+  # the search was successful so display the result properly by clearing away
+  # existing highlights and moving the cursor to the end of the result buffer
+  if [[ $_history_substring_search_refresh_display -eq 1 ]]; then
+    region_highlight=()
+    CURSOR=${#BUFFER}
+  fi
+
+  # highlight command line using zsh-syntax-highlighting
+  _zsh_highlight
+
+  # highlight the search query inside the command line
+  if [[ -n $_history_substring_search_query_highlight ]]; then
+    # highlight first matching query parts
+    local highlight_start_index=0
+    local highlight_end_index=0
+    for query_part in $_history_substring_search_query_parts; do
+      local escaped_query_part=${query_part//(#m)[\][()|\\*?#<>~^]/\\$MATCH}
+      # (i) get index of pattern
+      local query_part_match_index=${${BUFFER:$highlight_start_index}[(i)(#$HISTORY_SUBSTRING_SEARCH_GLOBBING_FLAGS)${escaped_query_part}]}
+      if [[ $query_part_match_index -le ${#BUFFER:$highlight_start_index} ]]; then
+        highlight_start_index=$(( $highlight_start_index + $query_part_match_index ))
+        highlight_end_index=$(( $highlight_start_index + ${#query_part} ))
+        region_highlight+=("$(($highlight_start_index - 1)) $(($highlight_end_index - 1)) $_history_substring_search_query_highlight")
+      fi
+    done
+  fi
+
+  # For debugging purposes:
+  # zle -R "mn: "$_history_substring_search_match_index" m#: "${#_history_substring_search_matches}
+  # read -k -t 200 && zle -U $REPLY
+
+  # Exit successfully from the history-substring-search-* widgets.
+  return 0
+}
+
+_history-substring-search-up-buffer() {
+  #
+  # Check if the UP arrow was pressed to move the cursor within a multi-line
+  # buffer. This amounts to three tests:
+  #
+  # 1. $#buflines -gt 1.
+  #
+  # 2. $CURSOR -ne $#BUFFER.
+  #
+  # 3. Check if we are on the first line of the current multi-line buffer.
+  #    If so, pressing UP would amount to leaving the multi-line buffer.
+  #
+  #    We check this by adding an extra "x" to $LBUFFER, which makes
+  #    sure that xlbuflines is always equal to the number of lines
+  #    until $CURSOR (including the line with the cursor on it).
+  #
+  local buflines XLBUFFER xlbuflines
+  buflines=(${(f)BUFFER})
+  XLBUFFER=$LBUFFER"x"
+  xlbuflines=(${(f)XLBUFFER})
+
+  if [[ $#buflines -gt 1 && $CURSOR -ne $#BUFFER && $#xlbuflines -ne 1 ]]; then
+    zle up-line-or-history
+    return 0
+  fi
+
+  return 1
+}
+
+_history-substring-search-down-buffer() {
+  #
+  # Check if the DOWN arrow was pressed to move the cursor within a multi-line
+  # buffer. This amounts to three tests:
+  #
+  # 1. $#buflines -gt 1.
+  #
+  # 2. $CURSOR -ne $#BUFFER.
+  #
+  # 3. Check if we are on the last line of the current multi-line buffer.
+  #    If so, pressing DOWN would amount to leaving the multi-line buffer.
+  #
+  #    We check this by adding an extra "x" to $RBUFFER, which makes
+  #    sure that xrbuflines is always equal to the number of lines
+  #    from $CURSOR (including the line with the cursor on it).
+  #
+  local buflines XRBUFFER xrbuflines
+  buflines=(${(f)BUFFER})
+  XRBUFFER="x"$RBUFFER
+  xrbuflines=(${(f)XRBUFFER})
+
+  if [[ $#buflines -gt 1 && $CURSOR -ne $#BUFFER && $#xrbuflines -ne 1 ]]; then
+    zle down-line-or-history
+    return 0
+  fi
+
+  return 1
+}
+
+_history-substring-search-up-history() {
+  #
+  # Behave like up in ZSH, except clear the $BUFFER
+  # when beginning of history is reached like in Fish.
+  #
+  if [[ -z $_history_substring_search_query ]]; then
+
+    # we have reached the absolute top of history
+    if [[ $HISTNO -eq 1 ]]; then
+      BUFFER=
+
+    # going up from somewhere below the top of history
+    else
+      zle up-line-or-history
+    fi
+
+    return 0
+  fi
+
+  return 1
+}
+
+_history-substring-search-down-history() {
+  #
+  # Behave like down-history in ZSH, except clear the
+  # $BUFFER when end of history is reached like in Fish.
+  #
+  if [[ -z $_history_substring_search_query ]]; then
+
+    # going down from the absolute top of history
+    if [[ $HISTNO -eq 1 && -z $BUFFER ]]; then
+      BUFFER=${history[1]}
+      _history_substring_search_refresh_display=1
+
+    # going down from somewhere above the bottom of history
+    else
+      zle down-line-or-history
+    fi
+
+    return 0
+  fi
+
+  return 1
+}
+
+_history_substring_search_process_raw_matches() {
+  #
+  # Process more outstanding raw matches and append any matches that need to
+  # be displayed to the user to _history_substring_search_matches.
+  # Return whether there were any more results appended.
+  #
+
+  #
+  # While we have more raw matches. Process them to see if there are any more
+  # matches that need to be displayed to the user.
+  #
+  while [[ $_history_substring_search_raw_match_index -lt $#_history_substring_search_raw_matches ]]; do
+    #
+    # Move on to the next raw entry and get its history index.
+    #
+    _history_substring_search_raw_match_index+=1
+    local index=${_history_substring_search_raw_matches[$_history_substring_search_raw_match_index]}
+
+    #
+    # If HISTORY_SUBSTRING_SEARCH_ENSURE_UNIQUE is set to a non-empty value,
+    # then ensure that only unique matches are presented to the user.
+    # When HIST_IGNORE_ALL_DUPS is set, ZSH already ensures a unique history,
+    # so in this case we do not need to do anything.
+    #
+    if [[ ! -o HIST_IGNORE_ALL_DUPS && -n $HISTORY_SUBSTRING_SEARCH_ENSURE_UNIQUE ]]; then
+      #
+      # Get the actual history entry at the new index, and check if we have
+      # already added it to _history_substring_search_matches.
+      #
+      local entry=${history[$index]}
+
+      if [[ -z ${_history_substring_search_unique_filter[$entry]} ]]; then
+        #
+        # This is a new unique entry. Add it to the filter and append the
+        # index to _history_substring_search_matches.
+        #
+        _history_substring_search_unique_filter[$entry]=1
+        _history_substring_search_matches+=($index)
+
+        #
+        # Indicate that we did find a match.
+        #
+        return 0
+      fi
+
+    else
+      #
+      # Just append the new history index to the processed matches.
+      #
+      _history_substring_search_matches+=($index)
+
+      #
+      # Indicate that we did find a match.
+      #
+      return 0
+    fi
+
+  done
+
+  #
+  # We are beyond the end of the list of raw matches. Indicate that no
+  # more matches are available.
+  #
+  return 1
+}
+
+_history-substring-search-has-next() {
+  #
+  # Predicate function that returns whether any more older matches are
+  # available.
+  #
+
+  if  [[ $_history_substring_search_match_index -lt $#_history_substring_search_matches ]]; then
+    #
+    # We did not reach the end of the processed list, so we do have further
+    # matches.
+    #
+    return 0
+
+  else
+    #
+    # We are at the end of the processed list. Try to process further
+    # unprocessed matches. _history_substring_search_process_raw_matches
+    # returns whether any more matches were available, so just return
+    # that result.
+    #
+    _history_substring_search_process_raw_matches
+    return $?
+  fi
+}
+
+_history-substring-search-has-prev() {
+  #
+  # Predicate function that returns whether any more younger matches are
+  # available.
+  #
+
+  if [[ $_history_substring_search_match_index -gt 1 ]]; then
+    #
+    # We did not reach the beginning of the processed list, so we do have
+    # further matches.
+    #
+    return 0
+
+  else
+    #
+    # We are at the beginning of the processed list. We do not have any more
+    # matches.
+    #
+    return 1
+  fi
+}
+
+_history-substring-search-found() {
+  #
+  # A match is available. The index of the match is held in
+  # $_history_substring_search_match_index
+  #
+  # 1. Make $BUFFER equal to the matching history entry.
+  #
+  # 2. Use $HISTORY_SUBSTRING_SEARCH_HIGHLIGHT_FOUND
+  #    to highlight the current buffer.
+  #
+  BUFFER=$history[$_history_substring_search_matches[$_history_substring_search_match_index]]
+  _history_substring_search_query_highlight=$HISTORY_SUBSTRING_SEARCH_HIGHLIGHT_FOUND
+}
+
+_history-substring-search-not-found() {
+  #
+  # No more matches are available.
+  #
+  # 1. Make $BUFFER equal to $_history_substring_search_query so the user can
+  #    revise it and search again.
+  #
+  # 2. Use $HISTORY_SUBSTRING_SEARCH_HIGHLIGHT_NOT_FOUND
+  #    to highlight the current buffer.
+  #
+  BUFFER=$_history_substring_search_query
+  _history_substring_search_query_highlight=$HISTORY_SUBSTRING_SEARCH_HIGHLIGHT_NOT_FOUND
+}
+
+_history-substring-search-up-search() {
+  _history_substring_search_refresh_display=1
+
+  #
+  # Select history entry during history-substring-down-search:
+  #
+  # The following variables have been initialized in
+  # _history-substring-search-up/down-search():
+  #
+  # $_history_substring_search_matches is the current list of matches that
+  # need to be displayed to the user.
+  # $_history_substring_search_match_index is the index of the current match
+  # that is being displayed to the user.
+  #
+  # The range of values that $_history_substring_search_match_index can take
+  # is: [0, $#_history_substring_search_matches + 1].  A value of 0
+  # indicates that we are beyond the beginning of
+  # $_history_substring_search_matches. A value of
+  # $#_history_substring_search_matches + 1 indicates that we are beyond
+  # the end of $_history_substring_search_matches and that we have also
+  # processed all entries in _history_substring_search_raw_matches.
+  #
+  # If $_history_substring_search_match_index equals
+  # $#_history_substring_search_matches and
+  # $_history_substring_search_raw_match_index is not greater than
+  # $#_history_substring_search_raw_matches, then we need to further process
+  # $_history_substring_search_raw_matches to see if there are any more
+  # entries that need to be displayed to the user.
+  #
+  # In _history-substring-search-up-search() the initial value of
+  # $_history_substring_search_match_index is 0. This value is set in
+  # _history-substring-search-begin(). _history-substring-search-up-search()
+  # will initially increment it to 1.
+  #
+
+  if [[ $_history_substring_search_match_index -gt $#_history_substring_search_matches ]]; then
+    #
+    # We are beyond the end of $_history_substring_search_matches. This
+    # can only happen if we have also exhausted the unprocessed matches in
+    # _history_substring_search_raw_matches.
+    #
+    # 1. Update display to indicate search not found.
+    #
+    _history-substring-search-not-found
+    return
+  fi
+
+  if _history-substring-search-has-next; then
+    #
+    # We do have older matches.
+    #
+    # 1. Move index to point to the next match.
+    # 2. Update display to indicate search found.
+    #
+    _history_substring_search_match_index+=1
+    _history-substring-search-found
+
+  else
+    #
+    # We do not have older matches.
+    #
+    # 1. Move the index beyond the end of
+    #    _history_substring_search_matches.
+    # 2. Update display to indicate search not found.
+    #
+    _history_substring_search_match_index+=1
+    _history-substring-search-not-found
+  fi
+
+  #
+  # When HIST_FIND_NO_DUPS is set, meaning that only unique command lines from
+  # history should be matched, make sure the new and old results are different.
+  #
+  # However, if the HIST_IGNORE_ALL_DUPS shell option, or
+  # HISTORY_SUBSTRING_SEARCH_ENSURE_UNIQUE is set, then we already have a
+  # unique history, so in this case we do not need to do anything.
+  #
+  if [[ -o HIST_IGNORE_ALL_DUPS || -n $HISTORY_SUBSTRING_SEARCH_ENSURE_UNIQUE ]]; then
+    return
+  fi
+
+  if [[ -o HIST_FIND_NO_DUPS && $BUFFER == $_history_substring_search_result ]]; then
+    #
+    # Repeat the current search so that a different (unique) match is found.
+    #
+    _history-substring-search-up-search
+  fi
+}
+
+_history-substring-search-down-search() {
+  _history_substring_search_refresh_display=1
+
+  #
+  # Select history entry during history-substring-down-search:
+  #
+  # The following variables have been initialized in
+  # _history-substring-search-up/down-search():
+  #
+  # $_history_substring_search_matches is the current list of matches that
+  # need to be displayed to the user.
+  # $_history_substring_search_match_index is the index of the current match
+  # that is being displayed to the user.
+  #
+  # The range of values that $_history_substring_search_match_index can take
+  # is: [0, $#_history_substring_search_matches + 1].  A value of 0
+  # indicates that we are beyond the beginning of
+  # $_history_substring_search_matches. A value of
+  # $#_history_substring_search_matches + 1 indicates that we are beyond
+  # the end of $_history_substring_search_matches and that we have also
+  # processed all entries in _history_substring_search_raw_matches.
+  #
+  # In _history-substring-search-down-search() the initial value of
+  # $_history_substring_search_match_index is 1. This value is set in
+  # _history-substring-search-begin(). _history-substring-search-down-search()
+  # will initially decrement it to 0.
+  #
+
+  if [[ $_history_substring_search_match_index -lt 1 ]]; then
+    #
+    # We are beyond the beginning of $_history_substring_search_matches.
+    #
+    # 1. Update display to indicate search not found.
+    #
+    _history-substring-search-not-found
+    return
+  fi
+
+  if _history-substring-search-has-prev; then
+    #
+    # We do have younger matches.
+    #
+    # 1. Move index to point to the previous match.
+    # 2. Update display to indicate search found.
+    #
+    _history_substring_search_match_index+=-1
+    _history-substring-search-found
+
+  else
+    #
+    # We do not have younger matches.
+    #
+    # 1. Move the index beyond the beginning of
+    #    _history_substring_search_matches.
+    # 2. Update display to indicate search not found.
+    #
+    _history_substring_search_match_index+=-1
+    _history-substring-search-not-found
+  fi
+
+  #
+  # When HIST_FIND_NO_DUPS is set, meaning that only unique command lines from
+  # history should be matched, make sure the new and old results are different.
+  #
+  # However, if the HIST_IGNORE_ALL_DUPS shell option, or
+  # HISTORY_SUBSTRING_SEARCH_ENSURE_UNIQUE is set, then we already have a
+  # unique history, so in this case we do not need to do anything.
+  #
+  if [[ -o HIST_IGNORE_ALL_DUPS || -n $HISTORY_SUBSTRING_SEARCH_ENSURE_UNIQUE ]]; then
+    return
+  fi
+
+  if [[ -o HIST_FIND_NO_DUPS && $BUFFER == $_history_substring_search_result ]]; then
+    #
+    # Repeat the current search so that a different (unique) match is found.
+    #
+    _history-substring-search-down-search
+  fi
+}
+
+# -*- mode: zsh; sh-indentation: 2; indent-tabs-mode: nil; sh-basic-offset: 2; -*-
+# vim: ft=zsh sw=2 ts=2 et
+