diff --git a/bin/autojump b/bin/autojump
index 03c0b09..d56b2ba 100755
--- a/bin/autojump
+++ b/bin/autojump
@@ -21,6 +21,7 @@
 
 from __future__ import print_function
 
+from argparse import ArgumentParser
 from difflib import SequenceMatcher
 from itertools import chain
 from math import sqrt
@@ -38,8 +39,6 @@ else:
     from itertools import ifilter
     from itertools import imap
 
-from argparse import ArgumentParser
-
 from data import dictify
 from data import entriefy
 from data import Entry
@@ -59,7 +58,7 @@ from utils import sanitize
 from utils import surround_quotes
 from utils import take
 
-VERSION = 'release-v21.8-alpha1'
+VERSION = '21.8-alpha'
 FUZZY_MATCH_THRESHOLD = 0.6
 TAB_ENTRIES_COUNT = 9
 TAB_SEPARATOR = '__'
@@ -102,7 +101,7 @@ def parse_arguments():
             help='add path')
     parser.add_argument(
             '-i', '--increase', metavar='WEIGHT', nargs='?', type=int,
-            const=20, default=False,
+            const=10, default=False,
             help='increase current directory weight')
     parser.add_argument(
             '-d', '--decrease', metavar='WEIGHT', nargs='?', type=int,
diff --git a/install.py b/install.py
new file mode 100755
index 0000000..c4e7f57
--- /dev/null
+++ b/install.py
@@ -0,0 +1,121 @@
+#!/usr/bin/env python2
+# -*- coding: utf-8 -*-
+
+from __future__ import print_function
+
+from argparse import ArgumentParser
+import os
+import shutil
+import sys
+
+
+SUPPORTED_SHELLS = ('bash', 'zsh', 'fish')
+
+
+def cp(src, dest, dryrun=False):
+    print("copying file: %s -> %s" % (src, dest))
+    if not dryrun:
+        shutil.copy(src, dest)
+
+
+def get_shell():
+    return os.path.basename(os.getenv('SHELL'))
+
+
+def mkdir(path, dryrun=False):
+    print("creating directory:", path)
+    if not dryrun and not os.path.exists(path):
+        os.makedirs(path)
+
+
+def parse_arguments():
+    default_destdir = os.path.join(os.path.expanduser("~"), '.autojump')
+    default_prefix = ''
+    default_zshshare = 'functions'
+
+    parser = ArgumentParser(
+            description='Installs autojump globally for root users, otherwise \
+                    installs in current user\'s home directory.')
+    parser.add_argument(
+            '-n', '--dryrun', action="store_true", default=False,
+            help='simulate installation')
+    parser.add_argument(
+            '-d', '--destdir', metavar='DIR', default=default_destdir,
+            help='set destination to DIR')
+    parser.add_argument(
+            '-p', '--prefix', metavar='DIR', default=default_prefix,
+            help='set prefix to DIR')
+    parser.add_argument(
+            '-z', '--zshshare', metavar='DIR', default=default_zshshare,
+            help='set zsh share destination to DIR')
+    parser.add_argument(
+            '-s', '--system', action="store_true", default=False,
+            help='install system wide for all users')
+
+    args = parser.parse_args()
+
+    if sys.version_info[0] == 2 and sys.version_info[1] < 7:
+        print("Python v2.7+ or v3.0+ required.", file=sys.stderr)
+        sys.exit(1)
+
+    if get_shell() not in SUPPORTED_SHELLS:
+        print("Unsupported shell: %s" % os.getenv('SHELL'), file=sys.stderr)
+        sys.exit(1)
+
+    if args.system:
+        if os.geteuid() != 0:
+            print("Please rerun as root for system-wide installation.", file=sys.stderr)
+            sys.exit(1)
+        if args.destdir == default_destdir:
+            args.destdir = '/'
+        if args.prefix == default_prefix:
+            args.prefix = '/usr/local'
+        if args.zshshare == default_zshshare:
+            args.zshshare = '/usr/share/zsh/site-functions'
+
+    return args
+
+
+def print_post_installation_message(etc_dir):
+    rcfile = '~/.%src' % get_shell()
+    aj_shell = '%s/autojump.%s' % (etc_dir, get_shell())
+    print("\nPlease manually add the following line to %s:\n" % rcfile)
+    print("\t[[ -s %s ]] && source %s\n" % (aj_shell, aj_shell))
+    print("Please restart terminal(s) before running autojump.\n")
+
+
+def main(args):
+    if args.dryrun:
+        print("Installing autojump to %s (DRYRUN)..." % args.destdir)
+    else:
+        print("Installing autojump to %s ..." % args.destdir)
+
+    bin_dir = os.path.join(args.destdir, args.prefix, 'bin')
+    etc_dir = os.path.join(args.destdir, 'etc/profile.d')
+    doc_dir = os.path.join(args.destdir, args.prefix, 'share/man/man1')
+    icon_dir = os.path.join(args.destdir, args.prefix, 'share/autojump')
+    zshshare_dir = os.path.join(args.destdir, args.zshshare)
+
+    mkdir(bin_dir, args.dryrun)
+    mkdir(etc_dir, args.dryrun)
+    mkdir(doc_dir, args.dryrun)
+    mkdir(icon_dir, args.dryrun)
+    mkdir(zshshare_dir, args.dryrun)
+
+    cp('./bin/autojump', bin_dir, args.dryrun)
+    cp('./bin/data.py', bin_dir, args.dryrun)
+    cp('./bin/utils.py', bin_dir, args.dryrun)
+    cp('./bin/autojump.sh', etc_dir, args.dryrun)
+    cp('./bin/autojump.bash', etc_dir, args.dryrun)
+    cp('./bin/autojump.fish', etc_dir, args.dryrun)
+    cp('./bin/autojump.zsh', etc_dir, args.dryrun)
+    cp('./bin/_j', zshshare_dir, args.dryrun)
+    cp('./bin/icon.png', icon_dir, args.dryrun)
+    cp('./docs/autojump.1', doc_dir, args.dryrun)
+
+    # TODO(ting|2013-12-30): modify autojump.sh for custom installs
+
+    print_post_installation_message(etc_dir)
+
+if __name__ == "__main__":
+    sys.exit(main(parse_arguments()))
diff --git a/install.sh b/install.sh
deleted file mode 100755
index 07dcd7f..0000000
--- a/install.sh
+++ /dev/null
@@ -1,249 +0,0 @@
-#!/usr/bin/env bash
-
-function help_msg {
-    echo "./install.sh [OPTION..]"
-    echo
-    echo " -a, --auto           Try to determine destdir, prefix (and zshshare if applicable)"
-    echo " -g, --global         Use default global settings (destdir=/; prefix=usr)"
-    echo " -l, --local          Use default local settings (destdir=~/.autojump)"
-    echo
-    echo " -d, --destdir PATH   Set install destination to PATH"
-    echo " -p, --prefix PATH    Use PATH as prefix"
-    echo " -Z, --zshshare PATH  Use PATH as zsh share destination"
-    echo
-    echo " -f, --force          Ignore Python version check"
-    echo " -n, --dry_run        Only show installation paths, don't install anything"
-    echo
-    echo "Will install autojump into:"
-    echo
-    echo ' Binaries:        $destdir$prefix/bin'
-    echo ' Documentation:   $destdir$prefix/share/man/man1'
-    echo ' Icon:            $destdir$prefix/share/autojump'
-    echo ' Shell scripts:   $destdir/etc/profile.d'
-    echo ' zsh functions:   $destdir$zshsharedir'
-    echo
-    echo 'Unless specified, $zshshare will be :'
-    echo ' - $destdir$prefix/functions for local installations'
-    echo ' - $destdir$prefix/share/zsh/site-functions for all other installations'
-}
-
-dry_run=
-local=
-global=
-force=
-shell=`echo ${SHELL} | awk -F/ '{ print $NF }'`
-destdir=
-prefix="usr/local"
-zshsharedir=
-
-# If no arguments passed, default to --auto.
-if [[ ${#} == 0 ]]; then
-    set -- "--auto"
-fi
-
-# Only dry-run should also default to --auto
-if [[ ${#} == 1 ]] && ([[ $1 = "-n" ]] || [[ $1 = "--dry-run" ]]); then
-    set -- "-n" "--auto"
-fi
-
-# Command line parsing
-while true; do
-    case "$1" in
-        -a|--auto)
-            if [[ ${UID} -eq 0 ]]; then
-                set -- "--global" "${@:2}"
-            else
-                set -- "--local" "${@:2}"
-            fi
-            ;;
-        -d|--destdir)
-            if [ $# -gt 1 ]; then
-                destdir=$2; shift 2
-            else
-                echo "--destdir or -d requires an argument" 1>&2
-            fi
-            ;;
-        -f|--force)
-            force=true
-            shift
-            if [[ ${#} == 0 ]]; then
-                set -- "--auto"
-            fi
-            ;;
-        -g|--global)
-            global=true
-            destdir=
-            prefix=usr
-            shift
-            ;;
-        -h|--help|-\?)
-            help_msg;
-            exit 0
-            ;;
-        -l|--local)
-            local=true
-            destdir=~/.autojump
-            prefix=
-            shift
-            ;;
-        -n|--dry_run)
-            dry_run=true
-            shift
-            ;;
-        -p|--prefix)
-            if [ $# -gt 1 ]; then
-                prefix=$2; shift 2
-            else
-                echo "--prefix or -p requires an argument" 1>&2
-                exit 1
-            fi
-            ;;
-        -Z|--zshshare)
-            if [ $# -gt 1 ]; then
-                zshsharedir=$2; shift 2
-            else
-                echo "--zshshare or -Z requires an argument" 1>&2
-                exit 1
-            fi
-            ;;
-        --)
-            shift
-            break
-            ;;
-        -*)
-            echo "invalid option: $1" 1>&2;
-            help_msg;
-            exit 1
-            ;;
-        *)
-            break
-            ;;
-    esac
-done
-
-# destdir must be a full path, and end with a slash
-if [[ -n ${destdir} ]]; then
-    if [[ ${destdir:0:1} != "/" ]]; then
-        echo "Error: destdir must be a full path" 1>&2
-        exit 1
-    fi
-    len=${#destdir}
-    if [[ ${destdir:len - 1} != "/" ]]; then
-        destdir="$destdir/"
-    fi
-else
-    destdir="/"
-fi
-
-# prefix should not start with, and end with, a slash
-if [[ -n ${prefix} ]]; then
-    if [[ ${prefix:0:1} == "/" ]]; then
-        prefix=${prefix:1}
-    fi
-    len=${#prefix}
-    if [[ ${prefix:len - 1} != "/" ]]; then
-        prefix="$prefix/"
-    fi
-fi
-
-# check shell support
-if [[ ${shell} != "bash" ]] && [[ ${shell} != "zsh" ]] \
-    && [[ ${shell} != "fish" ]]; then
-    echo "Unsupported shell (${shell}). Only Bash and Zsh shells are supported."
-    exit 1
-fi
-
-# zsh functions
-if [[ $shell == "zsh" ]]; then
-    if [[ -z $zshsharedir ]]; then
-        # if not set, use a default
-        if [[ $local ]]; then
-            zshsharedir="${prefix}functions"
-        else
-            zshsharedir="${prefix}share/zsh/site-functions"
-        fi
-    fi
-fi
-
-# check Python version
-if [ ! ${force} ]; then
-    python_version=`python -c 'import sys; print(sys.version_info[:])'`
-
-    if [[ ${python_version:1:1} -eq 2 && ${python_version:4:1} -lt 6 ]]; then
-        echo
-        echo "Incompatible Python version, please upgrade to v2.6+."
-        if [[ ${python_version:4:1} -ge 4 ]]; then
-            echo
-            echo "Alternatively, you can download v12 that supports Python v2.4+ from:"
-            echo
-            echo -e "\thttps://github.com/joelthelion/autojump/downloads"
-            echo
-        fi
-        exit 1
-    fi
-fi
-
-echo
-echo "Installating autojump..."
-echo
-echo "Destination:      $destdir"
-if [[ -n $prefix ]]; then
-    echo "Prefix:           /$prefix"
-fi
-echo
-echo "Binary:           ${destdir}${prefix}bin/"
-echo "Documentation:    ${destdir}${prefix}share/man/man1/"
-echo "Icon:             ${destdir}${prefix}share/autojump/"
-echo "Shell scripts:    ${destdir}etc/profile.d/"
-if [[ -z $shell ]] || [[ $shell == "zsh" ]]; then
-    echo "zsh functions:    ${destdir}${zshsharedir}"
-fi
-echo
-
-if [[ $dry_run ]]; then
-    echo "--dry_run (-n) used, stopping"
-    exit
-fi
-
-# INSTALL AUTOJUMP
-mkdir -p ${destdir}${prefix}share/autojump/ || exit 1
-mkdir -p ${destdir}${prefix}bin/ || exit 1
-mkdir -p ${destdir}${prefix}share/man/man1/ || exit 1
-cp -v ./bin/icon.png ${destdir}${prefix}share/autojump/ || exit 1
-cp -v ./bin/autojump ${destdir}${prefix}bin/ || exit 1
-cp -v ./bin/data.py ${destdir}${prefix}bin/ || exit 1
-cp -v ./bin/utils.py ${destdir}${prefix}bin/ || exit 1
-cp -v ./docs/autojump.1 ${destdir}${prefix}share/man/man1/ || exit 1
-mkdir -p ${destdir}etc/profile.d/ || exit 1
-cp -v ./bin/autojump.sh ${destdir}etc/profile.d/ || exit 1
-cp -v ./bin/autojump.bash ${destdir}etc/profile.d/ || exit 1
-cp -v ./bin/autojump.zsh ${destdir}etc/profile.d/ || exit 1
-cp -v ./bin/autojump.fish ${destdir}etc/profile.d/ || exit 1
-mkdir -p ${destdir}${zshsharedir} || exit 1
-# TODO: remove unused _j function (2013.02.01_1348, ting)
-install -v -m 0755 ./bin/_j ${destdir}${zshsharedir} || exit 1
-
-# MODIFY AUTOJUMP.SH FOR CUSTOM INSTALLS
-if [[ -z ${local} ]] && [[ -z ${global} ]]; then
-    sed -i "s:#custom#\t::g" ${destdir}etc/profile.d/autojump.sh
-    sed -i "s:destdir_install\t:${destdir}etc/profile.d:g" ${destdir}etc/profile.d/autojump.sh
-fi
-
-# DISPLAY ADD MESSAGE
-rc_file="~/.${shell}rc"
-if [[ `uname` == "Darwin" ]] && [[ ${shell} == "bash" ]]; then
-    rc_file="~/.bash_profile"
-fi
-
-aj_shell_file="${destdir}etc/profile.d/autojump.${shell}"
-if [[ ${local} ]]; then
-    aj_shell_file="~/.autojump/etc/profile.d/autojump.${shell}"
-fi
-
-echo
-echo "Please add the line to ${rc_file} :"
-echo
-echo -e "[[ -s ${aj_shell_file} ]] && . ${aj_shell_file}"
-echo
-echo "You need to run 'source ${rc_file}' before you can start using autojump. To remove autojump, run './uninstall.sh'"
-echo