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+# functions-common - Common functions used by DevStack components
+#
+# The canonical copy of this file is maintained in the DevStack repo.
+# All modifications should be made there and then sync'ed to other repos
+# as required.
+#
+# This file is sorted alphabetically within the function groups.
+#
+# - Config Functions
+# - Control Functions
+# - Distro Functions
+# - Git Functions
+# - OpenStack Functions
+# - Package Functions
+# - Process Functions
+# - Python Functions
+# - Service Functions
+#
+# The following variables are assumed to be defined by certain functions:
+#
+# - ``ENABLED_SERVICES``
+# - ``ERROR_ON_CLONE``
+# - ``FILES``
+# - ``OFFLINE``
+# - ``PIP_DOWNLOAD_CACHE``
+# - ``PIP_USE_MIRRORS``
+# - ``RECLONE``
+# - ``TRACK_DEPENDS``
+# - ``http_proxy``, ``https_proxy``, ``no_proxy``
+
+# Save trace setting
+XTRACE=$(set +o | grep xtrace)
+set +o xtrace
+
+
+# Config Functions
+# ================
+
+# Append a new option in an ini file without replacing the old value
+# iniadd config-file section option value1 value2 value3 ...
+function iniadd() {
+    local file=$1
+    local section=$2
+    local option=$3
+    shift 3
+    local values="$(iniget_multiline $file $section $option) $@"
+    iniset_multiline $file $section $option $values
+}
+
+# Comment an option in an INI file
+# inicomment config-file section option
+function inicomment() {
+    local file=$1
+    local section=$2
+    local option=$3
+    sed -i -e "/^\[$section\]/,/^\[.*\]/ s|^\($option[ \t]*=.*$\)|#\1|" "$file"
+}
+
+# Get an option from an INI file
+# iniget config-file section option
+function iniget() {
+    local file=$1
+    local section=$2
+    local option=$3
+    local line
+    line=$(sed -ne "/^\[$section\]/,/^\[.*\]/ { /^$option[ \t]*=/ p; }" "$file")
+    echo ${line#*=}
+}
+
+# Get a multiple line option from an INI file
+# iniget_multiline config-file section option
+function iniget_multiline() {
+    local file=$1
+    local section=$2
+    local option=$3
+    local values
+    values=$(sed -ne "/^\[$section\]/,/^\[.*\]/ { s/^$option[ \t]*=[ \t]*//gp; }" "$file")
+    echo ${values}
+}
+
+# Determinate is the given option present in the INI file
+# ini_has_option config-file section option
+function ini_has_option() {
+    local file=$1
+    local section=$2
+    local option=$3
+    local line
+    line=$(sed -ne "/^\[$section\]/,/^\[.*\]/ { /^$option[ \t]*=/ p; }" "$file")
+    [ -n "$line" ]
+}
+
+# Set an option in an INI file
+# iniset config-file section option value
+function iniset() {
+    local file=$1
+    local section=$2
+    local option=$3
+    local value=$4
+
+    [[ -z $section || -z $option ]] && return
+
+    if ! grep -q "^\[$section\]" "$file" 2>/dev/null; then
+        # Add section at the end
+        echo -e "\n[$section]" >>"$file"
+    fi
+    if ! ini_has_option "$file" "$section" "$option"; then
+        # Add it
+        sed -i -e "/^\[$section\]/ a\\
+$option = $value
+" "$file"
+    else
+        local sep=$(echo -ne "\x01")
+        # Replace it
+        sed -i -e '/^\['${section}'\]/,/^\[.*\]/ s'${sep}'^\('${option}'[ \t]*=[ \t]*\).*$'${sep}'\1'"${value}"${sep} "$file"
+    fi
+}
+
+# Set a multiple line option in an INI file
+# iniset_multiline config-file section option value1 value2 valu3 ...
+function iniset_multiline() {
+    local file=$1
+    local section=$2
+    local option=$3
+    shift 3
+    local values
+    for v in $@; do
+        # The later sed command inserts each new value in the line next to
+        # the section identifier, which causes the values to be inserted in
+        # the reverse order. Do a reverse here to keep the original order.
+        values="$v ${values}"
+    done
+    if ! grep -q "^\[$section\]" "$file"; then
+        # Add section at the end
+        echo -e "\n[$section]" >>"$file"
+    else
+        # Remove old values
+        sed -i -e "/^\[$section\]/,/^\[.*\]/ { /^$option[ \t]*=/ d; }" "$file"
+    fi
+    # Add new ones
+    for v in $values; do
+        sed -i -e "/^\[$section\]/ a\\
+$option = $v
+" "$file"
+    done
+}
+
+# Uncomment an option in an INI file
+# iniuncomment config-file section option
+function iniuncomment() {
+    local file=$1
+    local section=$2
+    local option=$3
+    sed -i -e "/^\[$section\]/,/^\[.*\]/ s|[^ \t]*#[ \t]*\($option[ \t]*=.*$\)|\1|" "$file"
+}
+
+# Normalize config values to True or False
+# Accepts as False: 0 no No NO false False FALSE
+# Accepts as True: 1 yes Yes YES true True TRUE
+# VAR=$(trueorfalse default-value test-value)
+function trueorfalse() {
+    local default=$1
+    local testval=$2
+
+    [[ -z "$testval" ]] && { echo "$default"; return; }
+    [[ "0 no No NO false False FALSE" =~ "$testval" ]] && { echo "False"; return; }
+    [[ "1 yes Yes YES true True TRUE" =~ "$testval" ]] && { echo "True"; return; }
+    echo "$default"
+}
+
+
+# Control Functions
+# =================
+
+# Prints backtrace info
+# filename:lineno:function
+# backtrace level
+function backtrace {
+    local level=$1
+    local deep=$((${#BASH_SOURCE[@]} - 1))
+    echo "[Call Trace]"
+    while [ $level -le $deep ]; do
+        echo "${BASH_SOURCE[$deep]}:${BASH_LINENO[$deep-1]}:${FUNCNAME[$deep-1]}"
+        deep=$((deep - 1))
+    done
+}
+
+# Prints line number and "message" then exits
+# die $LINENO "message"
+function die() {
+    local exitcode=$?
+    set +o xtrace
+    local line=$1; shift
+    if [ $exitcode == 0 ]; then
+        exitcode=1
+    fi
+    backtrace 2
+    err $line "$*"
+    exit $exitcode
+}
+
+# Checks an environment variable is not set or has length 0 OR if the
+# exit code is non-zero and prints "message" and exits
+# NOTE: env-var is the variable name without a '$'
+# die_if_not_set $LINENO env-var "message"
+function die_if_not_set() {
+    local exitcode=$?
+    FXTRACE=$(set +o | grep xtrace)
+    set +o xtrace
+    local line=$1; shift
+    local evar=$1; shift
+    if ! is_set $evar || [ $exitcode != 0 ]; then
+        die $line "$*"
+    fi
+    $FXTRACE
+}
+
+# Prints line number and "message" in error format
+# err $LINENO "message"
+function err() {
+    local exitcode=$?
+    errXTRACE=$(set +o | grep xtrace)
+    set +o xtrace
+    local msg="[ERROR] ${BASH_SOURCE[2]}:$1 $2"
+    echo $msg 1>&2;
+    if [[ -n ${SCREEN_LOGDIR} ]]; then
+        echo $msg >> "${SCREEN_LOGDIR}/error.log"
+    fi
+    $errXTRACE
+    return $exitcode
+}
+
+# Checks an environment variable is not set or has length 0 OR if the
+# exit code is non-zero and prints "message"
+# NOTE: env-var is the variable name without a '$'
+# err_if_not_set $LINENO env-var "message"
+function err_if_not_set() {
+    local exitcode=$?
+    errinsXTRACE=$(set +o | grep xtrace)
+    set +o xtrace
+    local line=$1; shift
+    local evar=$1; shift
+    if ! is_set $evar || [ $exitcode != 0 ]; then
+        err $line "$*"
+    fi
+    $errinsXTRACE
+    return $exitcode
+}
+
+# Exit after outputting a message about the distribution not being supported.
+# exit_distro_not_supported [optional-string-telling-what-is-missing]
+function exit_distro_not_supported {
+    if [[ -z "$DISTRO" ]]; then
+        GetDistro
+    fi
+
+    if [ $# -gt 0 ]; then
+        die $LINENO "Support for $DISTRO is incomplete: no support for $@"
+    else
+        die $LINENO "Support for $DISTRO is incomplete."
+    fi
+}
+
+# Test if the named environment variable is set and not zero length
+# is_set env-var
+function is_set() {
+    local var=\$"$1"
+    eval "[ -n \"$var\" ]" # For ex.: sh -c "[ -n \"$var\" ]" would be better, but several exercises depends on this
+}
+
+# Prints line number and "message" in warning format
+# warn $LINENO "message"
+function warn() {
+    local exitcode=$?
+    errXTRACE=$(set +o | grep xtrace)
+    set +o xtrace
+    local msg="[WARNING] ${BASH_SOURCE[2]}:$1 $2"
+    echo $msg 1>&2;
+    if [[ -n ${SCREEN_LOGDIR} ]]; then
+        echo $msg >> "${SCREEN_LOGDIR}/error.log"
+    fi
+    $errXTRACE
+    return $exitcode
+}
+
+
+# Distro Functions
+# ================
+
+# Determine OS Vendor, Release and Update
+# Tested with OS/X, Ubuntu, RedHat, CentOS, Fedora
+# Returns results in global variables:
+# os_VENDOR - vendor name
+# os_RELEASE - release
+# os_UPDATE - update
+# os_PACKAGE - package type
+# os_CODENAME - vendor's codename for release
+# GetOSVersion
+GetOSVersion() {
+    # Figure out which vendor we are
+    if [[ -x "`which sw_vers 2>/dev/null`" ]]; then
+        # OS/X
+        os_VENDOR=`sw_vers -productName`
+        os_RELEASE=`sw_vers -productVersion`
+        os_UPDATE=${os_RELEASE##*.}
+        os_RELEASE=${os_RELEASE%.*}
+        os_PACKAGE=""
+        if [[ "$os_RELEASE" =~ "10.7" ]]; then
+            os_CODENAME="lion"
+        elif [[ "$os_RELEASE" =~ "10.6" ]]; then
+            os_CODENAME="snow leopard"
+        elif [[ "$os_RELEASE" =~ "10.5" ]]; then
+            os_CODENAME="leopard"
+        elif [[ "$os_RELEASE" =~ "10.4" ]]; then
+            os_CODENAME="tiger"
+        elif [[ "$os_RELEASE" =~ "10.3" ]]; then
+            os_CODENAME="panther"
+        else
+            os_CODENAME=""
+        fi
+    elif [[ -x $(which lsb_release 2>/dev/null) ]]; then
+        os_VENDOR=$(lsb_release -i -s)
+        os_RELEASE=$(lsb_release -r -s)
+        os_UPDATE=""
+        os_PACKAGE="rpm"
+        if [[ "Debian,Ubuntu,LinuxMint" =~ $os_VENDOR ]]; then
+            os_PACKAGE="deb"
+        elif [[ "SUSE LINUX" =~ $os_VENDOR ]]; then
+            lsb_release -d -s | grep -q openSUSE
+            if [[ $? -eq 0 ]]; then
+                os_VENDOR="openSUSE"
+            fi
+        elif [[ $os_VENDOR == "openSUSE project" ]]; then
+            os_VENDOR="openSUSE"
+        elif [[ $os_VENDOR =~ Red.*Hat ]]; then
+            os_VENDOR="Red Hat"
+        fi
+        os_CODENAME=$(lsb_release -c -s)
+    elif [[ -r /etc/redhat-release ]]; then
+        # Red Hat Enterprise Linux Server release 5.5 (Tikanga)
+        # Red Hat Enterprise Linux Server release 7.0 Beta (Maipo)
+        # CentOS release 5.5 (Final)
+        # CentOS Linux release 6.0 (Final)
+        # Fedora release 16 (Verne)
+        # XenServer release 6.2.0-70446c (xenenterprise)
+        os_CODENAME=""
+        for r in "Red Hat" CentOS Fedora XenServer; do
+            os_VENDOR=$r
+            if [[ -n "`grep \"$r\" /etc/redhat-release`" ]]; then
+                ver=`sed -e 's/^.* \([0-9].*\) (\(.*\)).*$/\1\|\2/' /etc/redhat-release`
+                os_CODENAME=${ver#*|}
+                os_RELEASE=${ver%|*}
+                os_UPDATE=${os_RELEASE##*.}
+                os_RELEASE=${os_RELEASE%.*}
+                break
+            fi
+            os_VENDOR=""
+        done
+        os_PACKAGE="rpm"
+    elif [[ -r /etc/SuSE-release ]]; then
+        for r in openSUSE "SUSE Linux"; do
+            if [[ "$r" = "SUSE Linux" ]]; then
+                os_VENDOR="SUSE LINUX"
+            else
+                os_VENDOR=$r
+            fi
+
+            if [[ -n "`grep \"$r\" /etc/SuSE-release`" ]]; then
+                os_CODENAME=`grep "CODENAME = " /etc/SuSE-release | sed 's:.* = ::g'`
+                os_RELEASE=`grep "VERSION = " /etc/SuSE-release | sed 's:.* = ::g'`
+                os_UPDATE=`grep "PATCHLEVEL = " /etc/SuSE-release | sed 's:.* = ::g'`
+                break
+            fi
+            os_VENDOR=""
+        done
+        os_PACKAGE="rpm"
+    # If lsb_release is not installed, we should be able to detect Debian OS
+    elif [[ -f /etc/debian_version ]] && [[ $(cat /proc/version) =~ "Debian" ]]; then
+        os_VENDOR="Debian"
+        os_PACKAGE="deb"
+        os_CODENAME=$(awk '/VERSION=/' /etc/os-release | sed 's/VERSION=//' | sed -r 's/\"|\(|\)//g' | awk '{print $2}')
+        os_RELEASE=$(awk '/VERSION_ID=/' /etc/os-release | sed 's/VERSION_ID=//' | sed 's/\"//g')
+    fi
+    export os_VENDOR os_RELEASE os_UPDATE os_PACKAGE os_CODENAME
+}
+
+# Translate the OS version values into common nomenclature
+# Sets global ``DISTRO`` from the ``os_*`` values
+function GetDistro() {
+    GetOSVersion
+    if [[ "$os_VENDOR" =~ (Ubuntu) || "$os_VENDOR" =~ (Debian) ]]; then
+        # 'Everyone' refers to Ubuntu / Debian releases by the code name adjective
+        DISTRO=$os_CODENAME
+    elif [[ "$os_VENDOR" =~ (Fedora) ]]; then
+        # For Fedora, just use 'f' and the release
+        DISTRO="f$os_RELEASE"
+    elif [[ "$os_VENDOR" =~ (openSUSE) ]]; then
+        DISTRO="opensuse-$os_RELEASE"
+    elif [[ "$os_VENDOR" =~ (SUSE LINUX) ]]; then
+        # For SLE, also use the service pack
+        if [[ -z "$os_UPDATE" ]]; then
+            DISTRO="sle${os_RELEASE}"
+        else
+            DISTRO="sle${os_RELEASE}sp${os_UPDATE}"
+        fi
+    elif [[ "$os_VENDOR" =~ (Red Hat) || "$os_VENDOR" =~ (CentOS) ]]; then
+        # Drop the . release as we assume it's compatible
+        DISTRO="rhel${os_RELEASE::1}"
+    elif [[ "$os_VENDOR" =~ (XenServer) ]]; then
+        DISTRO="xs$os_RELEASE"
+    else
+        # Catch-all for now is Vendor + Release + Update
+        DISTRO="$os_VENDOR-$os_RELEASE.$os_UPDATE"
+    fi
+    export DISTRO
+}
+
+# Utility function for checking machine architecture
+# is_arch arch-type
+function is_arch {
+    ARCH_TYPE=$1
+
+    [[ "$(uname -m)" == "$ARCH_TYPE" ]]
+}
+
+# Determine if current distribution is a Fedora-based distribution
+# (Fedora, RHEL, CentOS, etc).
+# is_fedora
+function is_fedora {
+    if [[ -z "$os_VENDOR" ]]; then
+        GetOSVersion
+    fi
+
+    [ "$os_VENDOR" = "Fedora" ] || [ "$os_VENDOR" = "Red Hat" ] || [ "$os_VENDOR" = "CentOS" ]
+}
+
+
+# Determine if current distribution is a SUSE-based distribution
+# (openSUSE, SLE).
+# is_suse
+function is_suse {
+    if [[ -z "$os_VENDOR" ]]; then
+        GetOSVersion
+    fi
+
+    [ "$os_VENDOR" = "openSUSE" ] || [ "$os_VENDOR" = "SUSE LINUX" ]
+}
+
+
+# Determine if current distribution is an Ubuntu-based distribution
+# It will also detect non-Ubuntu but Debian-based distros
+# is_ubuntu
+function is_ubuntu {
+    if [[ -z "$os_PACKAGE" ]]; then
+        GetOSVersion
+    fi
+    [ "$os_PACKAGE" = "deb" ]
+}
+
+
+# Git Functions
+# =============
+
+# git clone only if directory doesn't exist already.  Since ``DEST`` might not
+# be owned by the installation user, we create the directory and change the
+# ownership to the proper user.
+# Set global RECLONE=yes to simulate a clone when dest-dir exists
+# Set global ERROR_ON_CLONE=True to abort execution with an error if the git repo
+# does not exist (default is False, meaning the repo will be cloned).
+# Uses global ``OFFLINE``
+# git_clone remote dest-dir branch
+function git_clone {
+    GIT_REMOTE=$1
+    GIT_DEST=$2
+    GIT_REF=$3
+    RECLONE=$(trueorfalse False $RECLONE)
+
+    if [[ "$OFFLINE" = "True" ]]; then
+        echo "Running in offline mode, clones already exist"
+        # print out the results so we know what change was used in the logs
+        cd $GIT_DEST
+        git show --oneline | head -1
+        return
+    fi
+
+    if echo $GIT_REF | egrep -q "^refs"; then
+        # If our branch name is a gerrit style refs/changes/...
+        if [[ ! -d $GIT_DEST ]]; then
+            [[ "$ERROR_ON_CLONE" = "True" ]] && \
+                die $LINENO "Cloning not allowed in this configuration"
+            git clone $GIT_REMOTE $GIT_DEST
+        fi
+        cd $GIT_DEST
+        git fetch $GIT_REMOTE $GIT_REF && git checkout FETCH_HEAD
+    else
+        # do a full clone only if the directory doesn't exist
+        if [[ ! -d $GIT_DEST ]]; then
+            [[ "$ERROR_ON_CLONE" = "True" ]] && \
+                die $LINENO "Cloning not allowed in this configuration"
+            git clone $GIT_REMOTE $GIT_DEST
+            cd $GIT_DEST
+            # This checkout syntax works for both branches and tags
+            git checkout $GIT_REF
+        elif [[ "$RECLONE" = "True" ]]; then
+            # if it does exist then simulate what clone does if asked to RECLONE
+            cd $GIT_DEST
+            # set the url to pull from and fetch
+            git remote set-url origin $GIT_REMOTE
+            git fetch origin
+            # remove the existing ignored files (like pyc) as they cause breakage
+            # (due to the py files having older timestamps than our pyc, so python
+            # thinks the pyc files are correct using them)
+            find $GIT_DEST -name '*.pyc' -delete
+
+            # handle GIT_REF accordingly to type (tag, branch)
+            if [[ -n "`git show-ref refs/tags/$GIT_REF`" ]]; then
+                git_update_tag $GIT_REF
+            elif [[ -n "`git show-ref refs/heads/$GIT_REF`" ]]; then
+                git_update_branch $GIT_REF
+            elif [[ -n "`git show-ref refs/remotes/origin/$GIT_REF`" ]]; then
+                git_update_remote_branch $GIT_REF
+            else
+                die $LINENO "$GIT_REF is neither branch nor tag"
+            fi
+
+        fi
+    fi
+
+    # print out the results so we know what change was used in the logs
+    cd $GIT_DEST
+    git show --oneline | head -1
+}
+
+# git update using reference as a branch.
+# git_update_branch ref
+function git_update_branch() {
+
+    GIT_BRANCH=$1
+
+    git checkout -f origin/$GIT_BRANCH
+    # a local branch might not exist
+    git branch -D $GIT_BRANCH || true
+    git checkout -b $GIT_BRANCH
+}
+
+# git update using reference as a branch.
+# git_update_remote_branch ref
+function git_update_remote_branch() {
+
+    GIT_BRANCH=$1
+
+    git checkout -b $GIT_BRANCH -t origin/$GIT_BRANCH
+}
+
+# git update using reference as a tag. Be careful editing source at that repo
+# as working copy will be in a detached mode
+# git_update_tag ref
+function git_update_tag() {
+
+    GIT_TAG=$1
+
+    git tag -d $GIT_TAG
+    # fetching given tag only
+    git fetch origin tag $GIT_TAG
+    git checkout -f $GIT_TAG
+}
+
+
+# OpenStack Functions
+# ===================
+
+# Get the default value for HOST_IP
+# get_default_host_ip fixed_range floating_range host_ip_iface host_ip
+function get_default_host_ip() {
+    local fixed_range=$1
+    local floating_range=$2
+    local host_ip_iface=$3
+    local host_ip=$4
+
+    # Find the interface used for the default route
+    host_ip_iface=${host_ip_iface:-$(ip route | sed -n '/^default/{ s/.*dev \(\w\+\)\s\+.*/\1/; p; }' | head -1)}
+    # Search for an IP unless an explicit is set by ``HOST_IP`` environment variable
+    if [ -z "$host_ip" -o "$host_ip" == "dhcp" ]; then
+        host_ip=""
+        host_ips=`LC_ALL=C ip -f inet addr show ${host_ip_iface} | awk '/inet/ {split($2,parts,"/");  print parts[1]}'`
+        for IP in $host_ips; do
+            # Attempt to filter out IP addresses that are part of the fixed and
+            # floating range. Note that this method only works if the ``netaddr``
+            # python library is installed. If it is not installed, an error
+            # will be printed and the first IP from the interface will be used.
+            # If that is not correct set ``HOST_IP`` in ``localrc`` to the correct
+            # address.
+            if ! (address_in_net $IP $fixed_range || address_in_net $IP $floating_range); then
+                host_ip=$IP
+                break;
+            fi
+        done
+    fi
+    echo $host_ip
+}
+
+# Grab a numbered field from python prettytable output
+# Fields are numbered starting with 1
+# Reverse syntax is supported: -1 is the last field, -2 is second to last, etc.
+# get_field field-number
+function get_field() {
+    while read data; do
+        if [ "$1" -lt 0 ]; then
+            field="(\$(NF$1))"
+        else
+            field="\$$(($1 + 1))"
+        fi
+        echo "$data" | awk -F'[ \t]*\\|[ \t]*' "{print $field}"
+    done
+}
+
+# Add a policy to a policy.json file
+# Do nothing if the policy already exists
+# ``policy_add policy_file policy_name policy_permissions``
+function policy_add() {
+    local policy_file=$1
+    local policy_name=$2
+    local policy_perm=$3
+
+    if grep -q ${policy_name} ${policy_file}; then
+        echo "Policy ${policy_name} already exists in ${policy_file}"
+        return
+    fi
+
+    # Add a terminating comma to policy lines without one
+    # Remove the closing '}' and all lines following to the end-of-file
+    local tmpfile=$(mktemp)
+    uniq ${policy_file} | sed -e '
+        s/]$/],/
+        /^[}]/,$d
+    ' > ${tmpfile}
+
+    # Append policy and closing brace
+    echo "    \"${policy_name}\": ${policy_perm}" >>${tmpfile}
+    echo "}" >>${tmpfile}
+
+    mv ${tmpfile} ${policy_file}
+}
+
+
+# Package Functions
+# =================
+
+# _get_package_dir
+function _get_package_dir() {
+    local pkg_dir
+    if is_ubuntu; then
+        pkg_dir=$FILES/apts
+    elif is_fedora; then
+        pkg_dir=$FILES/rpms
+    elif is_suse; then
+        pkg_dir=$FILES/rpms-suse
+    else
+        exit_distro_not_supported "list of packages"
+    fi
+    echo "$pkg_dir"
+}
+
+# Wrapper for ``apt-get`` to set cache and proxy environment variables
+# Uses globals ``OFFLINE``, ``*_proxy``
+# apt_get operation package [package ...]
+function apt_get() {
+    [[ "$OFFLINE" = "True" || -z "$@" ]] && return
+    local sudo="sudo"
+    [[ "$(id -u)" = "0" ]] && sudo="env"
+    $sudo DEBIAN_FRONTEND=noninteractive \
+        http_proxy=$http_proxy https_proxy=$https_proxy \
+        no_proxy=$no_proxy \
+        apt-get --option "Dpkg::Options::=--force-confold" --assume-yes "$@"
+}
+
+# get_packages() collects a list of package names of any type from the
+# prerequisite files in ``files/{apts|rpms}``.  The list is intended
+# to be passed to a package installer such as apt or yum.
+#
+# Only packages required for the services in 1st argument will be
+# included.  Two bits of metadata are recognized in the prerequisite files:
+#
+# - ``# NOPRIME`` defers installation to be performed later in `stack.sh`
+# - ``# dist:DISTRO`` or ``dist:DISTRO1,DISTRO2`` limits the selection
+#   of the package to the distros listed.  The distro names are case insensitive.
+function get_packages() {
+    local services=$@
+    local package_dir=$(_get_package_dir)
+    local file_to_parse
+    local service
+
+    if [[ -z "$package_dir" ]]; then
+        echo "No package directory supplied"
+        return 1
+    fi
+    if [[ -z "$DISTRO" ]]; then
+        GetDistro
+    fi
+    for service in ${services//,/ }; do
+        # Allow individual services to specify dependencies
+        if [[ -e ${package_dir}/${service} ]]; then
+            file_to_parse="${file_to_parse} $service"
+        fi
+        # NOTE(sdague) n-api needs glance for now because that's where
+        # glance client is
+        if [[ $service == n-api ]]; then
+            if [[ ! $file_to_parse =~ nova ]]; then
+                file_to_parse="${file_to_parse} nova"
+            fi
+            if [[ ! $file_to_parse =~ glance ]]; then
+                file_to_parse="${file_to_parse} glance"
+            fi
+        elif [[ $service == c-* ]]; then
+            if [[ ! $file_to_parse =~ cinder ]]; then
+                file_to_parse="${file_to_parse} cinder"
+            fi
+        elif [[ $service == ceilometer-* ]]; then
+            if [[ ! $file_to_parse =~ ceilometer ]]; then
+                file_to_parse="${file_to_parse} ceilometer"
+            fi
+        elif [[ $service == s-* ]]; then
+            if [[ ! $file_to_parse =~ swift ]]; then
+                file_to_parse="${file_to_parse} swift"
+            fi
+        elif [[ $service == n-* ]]; then
+            if [[ ! $file_to_parse =~ nova ]]; then
+                file_to_parse="${file_to_parse} nova"
+            fi
+        elif [[ $service == g-* ]]; then
+            if [[ ! $file_to_parse =~ glance ]]; then
+                file_to_parse="${file_to_parse} glance"
+            fi
+        elif [[ $service == key* ]]; then
+            if [[ ! $file_to_parse =~ keystone ]]; then
+                file_to_parse="${file_to_parse} keystone"
+            fi
+        elif [[ $service == q-* ]]; then
+            if [[ ! $file_to_parse =~ neutron ]]; then
+                file_to_parse="${file_to_parse} neutron"
+            fi
+        fi
+    done
+
+    for file in ${file_to_parse}; do
+        local fname=${package_dir}/${file}
+        local OIFS line package distros distro
+        [[ -e $fname ]] || continue
+
+        OIFS=$IFS
+        IFS=$'\n'
+        for line in $(<${fname}); do
+            if [[ $line =~ "NOPRIME" ]]; then
+                continue
+            fi
+
+            # Assume we want this package
+            package=${line%#*}
+            inst_pkg=1
+
+            # Look for # dist:xxx in comment
+            if [[ $line =~ (.*)#.*dist:([^ ]*) ]]; then
+                # We are using BASH regexp matching feature.
+                package=${BASH_REMATCH[1]}
+                distros=${BASH_REMATCH[2]}
+                # In bash ${VAR,,} will lowecase VAR
+                # Look for a match in the distro list
+                if [[ ! ${distros,,} =~ ${DISTRO,,} ]]; then
+                    # If no match then skip this package
+                    inst_pkg=0
+                fi
+            fi
+
+            # Look for # testonly in comment
+            if [[ $line =~ (.*)#.*testonly.* ]]; then
+                package=${BASH_REMATCH[1]}
+                # Are we installing test packages? (test for the default value)
+                if [[ $INSTALL_TESTONLY_PACKAGES = "False" ]]; then
+                    # If not installing test packages the skip this package
+                    inst_pkg=0
+                fi
+            fi
+
+            if [[ $inst_pkg = 1 ]]; then
+                echo $package
+            fi
+        done
+        IFS=$OIFS
+    done
+}
+
+# Distro-agnostic package installer
+# install_package package [package ...]
+function install_package() {
+    if is_ubuntu; then
+        [[ "$NO_UPDATE_REPOS" = "True" ]] || apt_get update
+        NO_UPDATE_REPOS=True
+
+        apt_get install "$@"
+    elif is_fedora; then
+        yum_install "$@"
+    elif is_suse; then
+        zypper_install "$@"
+    else
+        exit_distro_not_supported "installing packages"
+    fi
+}
+
+# Distro-agnostic function to tell if a package is installed
+# is_package_installed package [package ...]
+function is_package_installed() {
+    if [[ -z "$@" ]]; then
+        return 1
+    fi
+
+    if [[ -z "$os_PACKAGE" ]]; then
+        GetOSVersion
+    fi
+
+    if [[ "$os_PACKAGE" = "deb" ]]; then
+        dpkg -s "$@" > /dev/null 2> /dev/null
+    elif [[ "$os_PACKAGE" = "rpm" ]]; then
+        rpm --quiet -q "$@"
+    else
+        exit_distro_not_supported "finding if a package is installed"
+    fi
+}
+
+# Distro-agnostic package uninstaller
+# uninstall_package package [package ...]
+function uninstall_package() {
+    if is_ubuntu; then
+        apt_get purge "$@"
+    elif is_fedora; then
+        sudo yum remove -y "$@"
+    elif is_suse; then
+        sudo zypper rm "$@"
+    else
+        exit_distro_not_supported "uninstalling packages"
+    fi
+}
+
+# Wrapper for ``yum`` to set proxy environment variables
+# Uses globals ``OFFLINE``, ``*_proxy``
+# yum_install package [package ...]
+function yum_install() {
+    [[ "$OFFLINE" = "True" ]] && return
+    local sudo="sudo"
+    [[ "$(id -u)" = "0" ]] && sudo="env"
+    $sudo http_proxy=$http_proxy https_proxy=$https_proxy \
+        no_proxy=$no_proxy \
+        yum install -y "$@"
+}
+
+# zypper wrapper to set arguments correctly
+# zypper_install package [package ...]
+function zypper_install() {
+    [[ "$OFFLINE" = "True" ]] && return
+    local sudo="sudo"
+    [[ "$(id -u)" = "0" ]] && sudo="env"
+    $sudo http_proxy=$http_proxy https_proxy=$https_proxy \
+        zypper --non-interactive install --auto-agree-with-licenses "$@"
+}
+
+
+# Process Functions
+# =================
+
+# _run_process() is designed to be backgrounded by run_process() to simulate a
+# fork.  It includes the dirty work of closing extra filehandles and preparing log
+# files to produce the same logs as screen_it().  The log filename is derived
+# from the service name and global-and-now-misnamed SCREEN_LOGDIR
+# _run_process service "command-line"
+function _run_process() {
+    local service=$1
+    local command="$2"
+
+    # Undo logging redirections and close the extra descriptors
+    exec 1>&3
+    exec 2>&3
+    exec 3>&-
+    exec 6>&-
+
+    if [[ -n ${SCREEN_LOGDIR} ]]; then
+        exec 1>&${SCREEN_LOGDIR}/screen-${1}.${CURRENT_LOG_TIME}.log 2>&1
+        ln -sf ${SCREEN_LOGDIR}/screen-${1}.${CURRENT_LOG_TIME}.log ${SCREEN_LOGDIR}/screen-${1}.log
+
+        # TODO(dtroyer): Hack to get stdout from the Python interpreter for the logs.
+        export PYTHONUNBUFFERED=1
+    fi
+
+    exec /bin/bash -c "$command"
+    die "$service exec failure: $command"
+}
+
+# Helper to remove the ``*.failure`` files under ``$SERVICE_DIR/$SCREEN_NAME``.
+# This is used for ``service_check`` when all the ``screen_it`` are called finished
+# init_service_check
+function init_service_check() {
+    SCREEN_NAME=${SCREEN_NAME:-stack}
+    SERVICE_DIR=${SERVICE_DIR:-${DEST}/status}
+
+    if [[ ! -d "$SERVICE_DIR/$SCREEN_NAME" ]]; then
+        mkdir -p "$SERVICE_DIR/$SCREEN_NAME"
+    fi
+
+    rm -f "$SERVICE_DIR/$SCREEN_NAME"/*.failure
+}
+
+# Find out if a process exists by partial name.
+# is_running name
+function is_running() {
+    local name=$1
+    ps auxw | grep -v grep | grep ${name} > /dev/null
+    RC=$?
+    # some times I really hate bash reverse binary logic
+    return $RC
+}
+
+# run_process() launches a child process that closes all file descriptors and
+# then exec's the passed in command.  This is meant to duplicate the semantics
+# of screen_it() without screen.  PIDs are written to
+# $SERVICE_DIR/$SCREEN_NAME/$service.pid
+# run_process service "command-line"
+function run_process() {
+    local service=$1
+    local command="$2"
+
+    # Spawn the child process
+    _run_process "$service" "$command" &
+    echo $!
+}
+
+# Helper to launch a service in a named screen
+# screen_it service "command-line"
+function screen_it {
+    SCREEN_NAME=${SCREEN_NAME:-stack}
+    SERVICE_DIR=${SERVICE_DIR:-${DEST}/status}
+    USE_SCREEN=$(trueorfalse True $USE_SCREEN)
+
+    if is_service_enabled $1; then
+        # Append the service to the screen rc file
+        screen_rc "$1" "$2"
+
+        if [[ "$USE_SCREEN" = "True" ]]; then
+            screen -S $SCREEN_NAME -X screen -t $1
+
+            if [[ -n ${SCREEN_LOGDIR} ]]; then
+                screen -S $SCREEN_NAME -p $1 -X logfile ${SCREEN_LOGDIR}/screen-${1}.${CURRENT_LOG_TIME}.log
+                screen -S $SCREEN_NAME -p $1 -X log on
+                ln -sf ${SCREEN_LOGDIR}/screen-${1}.${CURRENT_LOG_TIME}.log ${SCREEN_LOGDIR}/screen-${1}.log
+            fi
+
+            # sleep to allow bash to be ready to be send the command - we are
+            # creating a new window in screen and then sends characters, so if
+            # bash isn't running by the time we send the command, nothing happens
+            sleep 1.5
+
+            NL=`echo -ne '\015'`
+            # This fun command does the following:
+            # - the passed server command is backgrounded
+            # - the pid of the background process is saved in the usual place
+            # - the server process is brought back to the foreground
+            # - if the server process exits prematurely the fg command errors
+            #   and a message is written to stdout and the service failure file
+            # The pid saved can be used in screen_stop() as a process group
+            # id to kill off all child processes
+            screen -S $SCREEN_NAME -p $1 -X stuff "$2 & echo \$! >$SERVICE_DIR/$SCREEN_NAME/$1.pid; fg || echo \"$1 failed to start\" | tee \"$SERVICE_DIR/$SCREEN_NAME/$1.failure\"$NL"
+        else
+            # Spawn directly without screen
+            run_process "$1" "$2" >$SERVICE_DIR/$SCREEN_NAME/$1.pid
+        fi
+    fi
+}
+
+# Screen rc file builder
+# screen_rc service "command-line"
+function screen_rc {
+    SCREEN_NAME=${SCREEN_NAME:-stack}
+    SCREENRC=$TOP_DIR/$SCREEN_NAME-screenrc
+    if [[ ! -e $SCREENRC ]]; then
+        # Name the screen session
+        echo "sessionname $SCREEN_NAME" > $SCREENRC
+        # Set a reasonable statusbar
+        echo "hardstatus alwayslastline '$SCREEN_HARDSTATUS'" >> $SCREENRC
+        # Some distributions override PROMPT_COMMAND for the screen terminal type - turn that off
+        echo "setenv PROMPT_COMMAND /bin/true" >> $SCREENRC
+        echo "screen -t shell bash" >> $SCREENRC
+    fi
+    # If this service doesn't already exist in the screenrc file
+    if ! grep $1 $SCREENRC 2>&1 > /dev/null; then
+        NL=`echo -ne '\015'`
+        echo "screen -t $1 bash" >> $SCREENRC
+        echo "stuff \"$2$NL\"" >> $SCREENRC
+
+        if [[ -n ${SCREEN_LOGDIR} ]]; then
+            echo "logfile ${SCREEN_LOGDIR}/screen-${1}.${CURRENT_LOG_TIME}.log" >>$SCREENRC
+            echo "log on" >>$SCREENRC
+        fi
+    fi
+}
+
+# Stop a service in screen
+# If a PID is available use it, kill the whole process group via TERM
+# If screen is being used kill the screen window; this will catch processes
+# that did not leave a PID behind
+# screen_stop service
+function screen_stop() {
+    SCREEN_NAME=${SCREEN_NAME:-stack}
+    SERVICE_DIR=${SERVICE_DIR:-${DEST}/status}
+    USE_SCREEN=$(trueorfalse True $USE_SCREEN)
+
+    if is_service_enabled $1; then
+        # Kill via pid if we have one available
+        if [[ -r $SERVICE_DIR/$SCREEN_NAME/$1.pid ]]; then
+            pkill -TERM -P -$(cat $SERVICE_DIR/$SCREEN_NAME/$1.pid)
+            rm $SERVICE_DIR/$SCREEN_NAME/$1.pid
+        fi
+        if [[ "$USE_SCREEN" = "True" ]]; then
+            # Clean up the screen window
+            screen -S $SCREEN_NAME -p $1 -X kill
+        fi
+    fi
+}
+
+# Helper to get the status of each running service
+# service_check
+function service_check() {
+    local service
+    local failures
+    SCREEN_NAME=${SCREEN_NAME:-stack}
+    SERVICE_DIR=${SERVICE_DIR:-${DEST}/status}
+
+
+    if [[ ! -d "$SERVICE_DIR/$SCREEN_NAME" ]]; then
+        echo "No service status directory found"
+        return
+    fi
+
+    # Check if there is any falure flag file under $SERVICE_DIR/$SCREEN_NAME
+    failures=`ls "$SERVICE_DIR/$SCREEN_NAME"/*.failure 2>/dev/null`
+
+    for service in $failures; do
+        service=`basename $service`
+        service=${service%.failure}
+        echo "Error: Service $service is not running"
+    done
+
+    if [ -n "$failures" ]; then
+        echo "More details about the above errors can be found with screen, with ./rejoin-stack.sh"
+    fi
+}
+
+
+# Python Functions
+# ================
+
+# Get the path to the pip command.
+# get_pip_command
+function get_pip_command() {
+    which pip || which pip-python
+
+    if [ $? -ne 0 ]; then
+        die $LINENO "Unable to find pip; cannot continue"
+    fi
+}
+
+# Get the path to the direcotry where python executables are installed.
+# get_python_exec_prefix
+function get_python_exec_prefix() {
+    if is_fedora || is_suse; then
+        echo "/usr/bin"
+    else
+        echo "/usr/local/bin"
+    fi
+}
+
+# Wrapper for ``pip install`` to set cache and proxy environment variables
+# Uses globals ``OFFLINE``, ``PIP_DOWNLOAD_CACHE``, ``PIP_USE_MIRRORS``,
+# ``TRACK_DEPENDS``, ``*_proxy``
+# pip_install package [package ...]
+function pip_install {
+    [[ "$OFFLINE" = "True" || -z "$@" ]] && return
+    if [[ -z "$os_PACKAGE" ]]; then
+        GetOSVersion
+    fi
+    if [[ $TRACK_DEPENDS = True ]]; then
+        source $DEST/.venv/bin/activate
+        CMD_PIP=$DEST/.venv/bin/pip
+        SUDO_PIP="env"
+    else
+        SUDO_PIP="sudo"
+        CMD_PIP=$(get_pip_command)
+    fi
+
+    # Mirror option not needed anymore because pypi has CDN available,
+    # but it's useful in certain circumstances
+    PIP_USE_MIRRORS=${PIP_USE_MIRRORS:-False}
+    if [[ "$PIP_USE_MIRRORS" != "False" ]]; then
+        PIP_MIRROR_OPT="--use-mirrors"
+    fi
+
+    # pip < 1.4 has a bug where it will use an already existing build
+    # directory unconditionally.  Say an earlier component installs
+    # foo v1.1; pip will have built foo's source in
+    # /tmp/$USER-pip-build.  Even if a later component specifies foo <
+    # 1.1, the existing extracted build will be used and cause
+    # confusing errors.  By creating unique build directories we avoid
+    # this problem. See https://github.com/pypa/pip/issues/709
+    local pip_build_tmp=$(mktemp --tmpdir -d pip-build.XXXXX)
+
+    $SUDO_PIP PIP_DOWNLOAD_CACHE=${PIP_DOWNLOAD_CACHE:-/var/cache/pip} \
+        HTTP_PROXY=$http_proxy \
+        HTTPS_PROXY=$https_proxy \
+        NO_PROXY=$no_proxy \
+        $CMD_PIP install --build=${pip_build_tmp} \
+        $PIP_MIRROR_OPT $@ \
+        && $SUDO_PIP rm -rf ${pip_build_tmp}
+}
+
+
+# Service Functions
+# =================
+
+# remove extra commas from the input string (i.e. ``ENABLED_SERVICES``)
+# _cleanup_service_list service-list
+function _cleanup_service_list () {
+    echo "$1" | sed -e '
+        s/,,/,/g;
+        s/^,//;
+        s/,$//
+    '
+}
+
+# disable_all_services() removes all current services
+# from ``ENABLED_SERVICES`` to reset the configuration
+# before a minimal installation
+# Uses global ``ENABLED_SERVICES``
+# disable_all_services
+function disable_all_services() {
+    ENABLED_SERVICES=""
+}
+
+# Remove all services starting with '-'.  For example, to install all default
+# services except rabbit (rabbit) set in ``localrc``:
+# ENABLED_SERVICES+=",-rabbit"
+# Uses global ``ENABLED_SERVICES``
+# disable_negated_services
+function disable_negated_services() {
+    local tmpsvcs="${ENABLED_SERVICES}"
+    local service
+    for service in ${tmpsvcs//,/ }; do
+        if [[ ${service} == -* ]]; then
+            tmpsvcs=$(echo ${tmpsvcs}|sed -r "s/(,)?(-)?${service#-}(,)?/,/g")
+        fi
+    done
+    ENABLED_SERVICES=$(_cleanup_service_list "$tmpsvcs")
+}
+
+# disable_service() removes the services passed as argument to the
+# ``ENABLED_SERVICES`` list, if they are present.
+#
+# For example:
+#   disable_service rabbit
+#
+# This function does not know about the special cases
+# for nova, glance, and neutron built into is_service_enabled().
+# Uses global ``ENABLED_SERVICES``
+# disable_service service [service ...]
+function disable_service() {
+    local tmpsvcs=",${ENABLED_SERVICES},"
+    local service
+    for service in $@; do
+        if is_service_enabled $service; then
+            tmpsvcs=${tmpsvcs//,$service,/,}
+        fi
+    done
+    ENABLED_SERVICES=$(_cleanup_service_list "$tmpsvcs")
+}
+
+# enable_service() adds the services passed as argument to the
+# ``ENABLED_SERVICES`` list, if they are not already present.
+#
+# For example:
+#   enable_service qpid
+#
+# This function does not know about the special cases
+# for nova, glance, and neutron built into is_service_enabled().
+# Uses global ``ENABLED_SERVICES``
+# enable_service service [service ...]
+function enable_service() {
+    local tmpsvcs="${ENABLED_SERVICES}"
+    for service in $@; do
+        if ! is_service_enabled $service; then
+            tmpsvcs+=",$service"
+        fi
+    done
+    ENABLED_SERVICES=$(_cleanup_service_list "$tmpsvcs")
+    disable_negated_services
+}
+
+# is_service_enabled() checks if the service(s) specified as arguments are
+# enabled by the user in ``ENABLED_SERVICES``.
+#
+# Multiple services specified as arguments are ``OR``'ed together; the test
+# is a short-circuit boolean, i.e it returns on the first match.
+#
+# There are special cases for some 'catch-all' services::
+#   **nova** returns true if any service enabled start with **n-**
+#   **cinder** returns true if any service enabled start with **c-**
+#   **ceilometer** returns true if any service enabled start with **ceilometer**
+#   **glance** returns true if any service enabled start with **g-**
+#   **neutron** returns true if any service enabled start with **q-**
+#   **swift** returns true if any service enabled start with **s-**
+#   **trove** returns true if any service enabled start with **tr-**
+#   For backward compatibility if we have **swift** in ENABLED_SERVICES all the
+#   **s-** services will be enabled. This will be deprecated in the future.
+#
+# Cells within nova is enabled if **n-cell** is in ``ENABLED_SERVICES``.
+# We also need to make sure to treat **n-cell-region** and **n-cell-child**
+# as enabled in this case.
+#
+# Uses global ``ENABLED_SERVICES``
+# is_service_enabled service [service ...]
+function is_service_enabled() {
+    services=$@
+    for service in ${services}; do
+        [[ ,${ENABLED_SERVICES}, =~ ,${service}, ]] && return 0
+
+        # Look for top-level 'enabled' function for this service
+        if type is_${service}_enabled >/dev/null 2>&1; then
+            # A function exists for this service, use it
+            is_${service}_enabled
+            return $?
+        fi
+
+        # TODO(dtroyer): Remove these legacy special-cases after the is_XXX_enabled()
+        #                are implemented
+
+        [[ ${service} == n-cell-* && ${ENABLED_SERVICES} =~ "n-cell" ]] && return 0
+        [[ ${service} == "nova" && ${ENABLED_SERVICES} =~ "n-" ]] && return 0
+        [[ ${service} == "cinder" && ${ENABLED_SERVICES} =~ "c-" ]] && return 0
+        [[ ${service} == "ceilometer" && ${ENABLED_SERVICES} =~ "ceilometer-" ]] && return 0
+        [[ ${service} == "glance" && ${ENABLED_SERVICES} =~ "g-" ]] && return 0
+        [[ ${service} == "ironic" && ${ENABLED_SERVICES} =~ "ir-" ]] && return 0
+        [[ ${service} == "neutron" && ${ENABLED_SERVICES} =~ "q-" ]] && return 0
+        [[ ${service} == "trove" && ${ENABLED_SERVICES} =~ "tr-" ]] && return 0
+        [[ ${service} == "swift" && ${ENABLED_SERVICES} =~ "s-" ]] && return 0
+        [[ ${service} == s-* && ${ENABLED_SERVICES} =~ "swift" ]] && return 0
+    done
+    return 1
+}
+
+# Toggle enable/disable_service for services that must run exclusive of each other
+#  $1 The name of a variable containing a space-separated list of services
+#  $2 The name of a variable in which to store the enabled service's name
+#  $3 The name of the service to enable
+function use_exclusive_service {
+    local options=${!1}
+    local selection=$3
+    out=$2
+    [ -z $selection ] || [[ ! "$options" =~ "$selection" ]] && return 1
+    for opt in $options;do
+        [[ "$opt" = "$selection" ]] && enable_service $opt || disable_service $opt
+    done
+    eval "$out=$selection"
+    return 0
+}
+
+
+# System Function
+# ===============
+
+# Only run the command if the target file (the last arg) is not on an
+# NFS filesystem.
+function _safe_permission_operation() {
+    local args=( $@ )
+    local last
+    local sudo_cmd
+    local dir_to_check
+
+    let last="${#args[*]} - 1"
+
+    dir_to_check=${args[$last]}
+    if [ ! -d "$dir_to_check" ]; then
+        dir_to_check=`dirname "$dir_to_check"`
+    fi
+
+    if is_nfs_directory "$dir_to_check" ; then
+        return 0
+    fi
+
+    if [[ $TRACK_DEPENDS = True ]]; then
+        sudo_cmd="env"
+    else
+        sudo_cmd="sudo"
+    fi
+
+    $sudo_cmd $@
+}
+
+# Exit 0 if address is in network or 1 if address is not in network
+# ip-range is in CIDR notation: 1.2.3.4/20
+# address_in_net ip-address ip-range
+function address_in_net() {
+    local ip=$1
+    local range=$2
+    local masklen=${range#*/}
+    local network=$(maskip ${range%/*} $(cidr2netmask $masklen))
+    local subnet=$(maskip $ip $(cidr2netmask $masklen))
+    [[ $network == $subnet ]]
+}
+
+# Add a user to a group.
+# add_user_to_group user group
+function add_user_to_group() {
+    local user=$1
+    local group=$2
+
+    if [[ -z "$os_VENDOR" ]]; then
+        GetOSVersion
+    fi
+
+    # SLE11 and openSUSE 12.2 don't have the usual usermod
+    if ! is_suse || [[ "$os_VENDOR" = "openSUSE" && "$os_RELEASE" != "12.2" ]]; then
+        sudo usermod -a -G "$group" "$user"
+    else
+        sudo usermod -A "$group" "$user"
+    fi
+}
+
+# Convert CIDR notation to a IPv4 netmask
+# cidr2netmask cidr-bits
+function cidr2netmask() {
+    local maskpat="255 255 255 255"
+    local maskdgt="254 252 248 240 224 192 128"
+    set -- ${maskpat:0:$(( ($1 / 8) * 4 ))}${maskdgt:$(( (7 - ($1 % 8)) * 4 )):3}
+    echo ${1-0}.${2-0}.${3-0}.${4-0}
+}
+
+# Gracefully cp only if source file/dir exists
+# cp_it source destination
+function cp_it {
+    if [ -e $1 ] || [ -d $1 ]; then
+        cp -pRL $1 $2
+    fi
+}
+
+# HTTP and HTTPS proxy servers are supported via the usual environment variables [1]
+# ``http_proxy``, ``https_proxy`` and ``no_proxy``. They can be set in
+# ``localrc`` or on the command line if necessary::
+#
+# [1] http://www.w3.org/Daemon/User/Proxies/ProxyClients.html
+#
+#     http_proxy=http://proxy.example.com:3128/ no_proxy=repo.example.net ./stack.sh
+
+function export_proxy_variables() {
+    if [[ -n "$http_proxy" ]]; then
+        export http_proxy=$http_proxy
+    fi
+    if [[ -n "$https_proxy" ]]; then
+        export https_proxy=$https_proxy
+    fi
+    if [[ -n "$no_proxy" ]]; then
+        export no_proxy=$no_proxy
+    fi
+}
+
+# Returns true if the directory is on a filesystem mounted via NFS.
+function is_nfs_directory() {
+    local mount_type=`stat -f -L -c %T $1`
+    test "$mount_type" == "nfs"
+}
+
+# Return the network portion of the given IP address using netmask
+# netmask is in the traditional dotted-quad format
+# maskip ip-address netmask
+function maskip() {
+    local ip=$1
+    local mask=$2
+    local l="${ip%.*}"; local r="${ip#*.}"; local n="${mask%.*}"; local m="${mask#*.}"
+    local subnet=$((${ip%%.*}&${mask%%.*})).$((${r%%.*}&${m%%.*})).$((${l##*.}&${n##*.})).$((${ip##*.}&${mask##*.}))
+    echo $subnet
+}
+
+# Service wrapper to restart services
+# restart_service service-name
+function restart_service() {
+    if is_ubuntu; then
+        sudo /usr/sbin/service $1 restart
+    else
+        sudo /sbin/service $1 restart
+    fi
+}
+
+# Only change permissions of a file or directory if it is not on an
+# NFS filesystem.
+function safe_chmod() {
+    _safe_permission_operation chmod $@
+}
+
+# Only change ownership of a file or directory if it is not on an NFS
+# filesystem.
+function safe_chown() {
+    _safe_permission_operation chown $@
+}
+
+# Service wrapper to start services
+# start_service service-name
+function start_service() {
+    if is_ubuntu; then
+        sudo /usr/sbin/service $1 start
+    else
+        sudo /sbin/service $1 start
+    fi
+}
+
+# Service wrapper to stop services
+# stop_service service-name
+function stop_service() {
+    if is_ubuntu; then
+        sudo /usr/sbin/service $1 stop
+    else
+        sudo /sbin/service $1 stop
+    fi
+}
+
+
+# Restore xtrace
+$XTRACE
+
+# Local variables:
+# mode: shell-script
+# End: