A shell script to display the 'crouton' version in the host and optionally update it. If a local version of 'crouton' cannot be found it downloads & installs one. Also, optionally displays the croutonversion and architecture ([-s option]) and other info. ([-v option]) about all [default] or given chroots.

crv

#!/bin/sh

###
### Set Variables
APPLICATION="${0##*/}"
CHECK_IT=''
CHROOT_LOC=/usr/local/chroots
[   -d /var/crouton/chroots ] && CHROOT_LOC='/var/crouton/chroots'
[ ! -d "$CHROOT_LOC" ]        && CHROOT_LOC=''
CHROOT_NAME=''
CROUTON_LOC="`which crouton 2>/dev/null`"
if [ ! -s "$CROUTON_LOC" ]; then CROUTON_LOC=''; fi
CROUTON_NEW=''
CROUTON_PAR="`dirname $CROUTON_LOC 2>/dev/null`"
if [ ! -d "$CROUTON_PAR" ]; then CROUTON_PAR=''; fi
DISPLAY_ALL=''
DOWNLOAD_LOC="$HOME/Downloads"
DOWNLOAD_NEW=''
EACH=''
HOST=''
LATEST=''
LIST_ONLY=''
UPDATE=''

# VERSION format: date '+%Y%m%d%H%M%S'
VERSION='20140319195918'
VERHIST="\
$APPLICATION-20140319195918 : Copied latest 'private' version to 'public' area
$APPLICATION-20140319195918 + and added version tracking and version history option"

###
### Define Colors
C0="\033[0m" # Reset Text
Bold="\033[1m" # Bold Text
Underline="\033[4m" # Underline Text
Black='\033[30m'
Red='\033[31m'
Green='\033[32m'
Brown='\033[33m'
Blue='\033[34m'
Purple='\033[35m'
Cyan='\033[36m'
Light_Grey='\033[37m'
Dark_Grey='\033[1;30m'
Light_Red='\033[1;31m'
Light_Green='\033[1;32m'
Yellow='\033[1;33m'
Light_Blue='\033[1;34m'
Light_Purple='\033[1;35m'
Light_Cyan='\033[1;36m'
White='\033[1;37m'

###
### Define USAGE
USAGE="${Bold}USAGE: $ APPLICATION [options] [chroot_name]
${Yellow}
A shell script to display the 'crouton' version in the host and optionally update it.
If a local version of 'crouton' cannot be found it downloads & installs one.

Also, optionally displays the croutonversion and architecture ([-s option])
and other info. ([-v option]) about all [default] or given chroots.
${C0}${Light_Cyan}
Options:
   -s            Displays only the 'croutonversion' & 'architecture' of all [default] or given chroots
   -v            Displays the complete output of 'croutonversion' of all [default] or given chroots
   -c            Checks the local host 'crouton' version against the latest version
   -C            Checks the local host 'crouton' version against the latest version & updates if needed
   -l            Lists the chroot(s) in $CHROOT_LOC [default] & exits
   -t CHROOT     Lists the chroot's DEs/targets & exits - chroot_name required
#  -u CHROOT     Displays the chroot's version & updates 'crouton' if needed - chroot_name required # BROKEN - inoperative #
   -f DOWNLOADS  Changes the destination of the downloaded crouton - Default: '$DOWNLOAD_LOC'
   -p CHROOTS    Changes the location of your chroot(s) folder - Default: '$CHROOT_LOC'

   -h            Displays this usage message and exits ${C0}
   -V            Version & History - print version number plus version history & exit
"

###
### Exits the script with exit code $1, spitting out message $@ to stderr
error() {
    local ecode="$1"
    shift
    echo "$*" 1>&2
    exit "$ecode"
}

###
### Display a help message if requested
if [ "$1" = "--help" ]
then error 0 "$USAGE"; fi

###
### Get command line parameters
while getopts svcClt:u:f:p:hV OPT; do
  case $OPT in
    s) DISPLAY_ALL='n';;
    v) DISPLAY_ALL='y';;
    c) CHECK_IT='y';;
    C) CHECK_IT='y'; UPDATE='y';;
    l) LIST_ONLY='y';;
    t) LIST_ONLY='y'; CHROOT_NAME="$OPTARG";;
    u) UPDATE='-du'; CHROOT_NAME="$OPTARG";;
    f) DOWNLOAD_NEW='y'; DOWNLOAD_LOC="`readlink -f "$OPTARG"`";;
    p) CHROOT_LOC="`readlink -f "$OPTARG"`";;
    h) error 0 "$USAGE";;
    V) error 0 "${APPLICATION}-${VERSION}\n${VERHIST}" ;;
     \?) error 2 "$USAGE";;
  esac
done
shift "$((OPTIND-1))"

###
### List chroot's targets if requested
if [ -n "$LIST_ONLY" -a -n "$CHROOT_NAME" ]
then
    targetfile="$CHROOT_LOC/$CHROOT_NAME/etc/crouton/targets"
    if [ -r "$targetfile" ]; then
      echo -n "DEs/targets in '$CHROOT_NAME': " 1>&2
      error 0 "`sed 's/^,//' "$targetfile" 2>/dev/null`"
    else
      error 1 "${Light_Red}Sorry, '$targetfile' not found.$C0"
    fi
fi

###
### List chroots if requested
if [ -n "$LIST_ONLY" ]
then
  echo -n "chroot(s) in '$CHROOT_LOC': " 1>&2
  error 0 "`ls -Cm "$CHROOT_LOC" 2>/dev/null`"
fi

###
### Check to see: if root, assign a new Downloads folder
##+ since /root/Downloads is not present or writeable by default.
if [ "$UID" = 0 -o "$USER" = 'root' ]; then
  if [ -z "$DOWNLOAD_NEW" ]; then
    DOWNLOAD_LOC='/home/chronos/user/Downloads'
  fi
  echo "${Yellow}'$APPLICATION' will be run as 'root' but 'crouton' will$C0" 1>&2
  echo "${Yellow}be saved to '$DOWNLOAD_LOC' if needed.$C0" 1>&2
fi

###
### Make sure the Downloads folder is a valid directory
if [ ! -d "$DOWNLOAD_LOC" ]; then
  error 1 "${Light_Red}Sorry, no folder named: $DOWNLOAD_LOC${C0}"
elif [ -n "$DOWNLOAD_NEW" ]; then
  echo "New Downloads folder: '$DOWNLOAD_LOC'" 1>&2
fi

###
### Check local host for 'crouton' and get one if needed
if [ -z "$CROUTON_LOC" ]
then
  if [ -s "$DOWNLOAD_LOC/crouton" ]
  then
    CROUTON_LOC="$DOWNLOAD_LOC/crouton"
    CROUTON_PAR="`dirname $CROUTON_LOC`"
  else
    echo "${Light_Red}Can't find 'crouton' on the host, so...${C0}" 1>&2
    sudo rm /tmp/crouton 2>/dev/null
    echo "Retreiving latest version of crouton." 1>&2
    wget -qO /tmp/crouton http://goo.gl/fd3zc
    if [ -s /tmp/crouton ]; then
      echo "${Light_Blue}Saving the latest version to '$DOWNLOAD_LOC/crouton'.${C0}" 1>&2
      sudo cp -f /tmp/crouton $DOWNLOAD_LOC
      sudo chmod +x $DOWNLOAD_LOC/crouton
      CROUTON_LOC="$DOWNLOAD_LOC/crouton"
      CROUTON_PAR="`dirname $CROUTON_LOC`"
      CROUTON_NEW='y'
    else
      error 2 "${Yellow}Oh no - couldn't grab the latest 'crouton'!!!$C0"
    fi
    if [ -n "$CHECK_IT" ]
    then
      CHECK_IT='n'
      echo "${White}Checking &/or Updating no longer required...${C0}" 1>&2
      echo "${Green}latest: $DOWNLOAD_LOC/`sh $DOWNLOAD_LOC/crouton -V 2>&1`${C0}" 1>&2
    fi
  fi
fi

###
### Check for the latest version of 'crouton' and update if requested
if [ "$CHECK_IT" = 'y' ]
then
  sudo rm /tmp/crouton 2>/dev/null
  echo "Retreiving latest version of crouton." 1>&2
  wget -qO /tmp/crouton http://goo.gl/fd3zc
  if [ -s /tmp/crouton ]; then
    HOST="`sh $CROUTON_LOC -V 2>&1`"
    LATEST="`sh /tmp/crouton -V 2>&1`"
    echo "${Green}latest: /tmp/$LATEST${C0}" 1>&2
    echo -n "${Blue}host: $CROUTON_PAR/$HOST${C0}" 1>&2
    if [ ! "$HOST" = "$LATEST" ]
    then echo "${Bold}${Light_Red} *** THE HOST NEEDS AN UPDATE ***${C0}" 1>&2
      if [ -n "$UPDATE" ]
      then
        echo "${Light_Blue}Saving the latest version to '$DOWNLOAD_LOC/crouton'.${C0}" 1>&2
        sudo cp -f /tmp/crouton $DOWNLOAD_LOC
        sudo chmod +x $DOWNLOAD_LOC/crouton
        CROUTON_NEW='y'
        if [ -n "$CROUTON_LOC" ]
        then
          echo "${Light_Blue}Also saving the latest version to '$CROUTON_LOC'.${C0}" 1>&2
          sudo cp -f /tmp/crouton $CROUTON_LOC
          sudo chmod +x $CROUTON_LOC
          sudo chown chronos:chronos $CROUTON_LOC
        fi
      else
        echo "${Yellow}...but, no 'crouton' update requested...${C0}" 1>&2
      fi
    else
      echo "${Light_Green} *** Your up-to-date ***${C0}" 1>&2
    fi
  else
    error 2 "${Yellow}Oh no - couldn't grab the latest 'crouton'!!!$C0"
  fi
else
  echo "${Blue}host: $CROUTON_PAR/`sh $CROUTON_LOC -V 2>&1`${C0}" 1>&2
fi

###
### Get a valid chroot_name or names
if [ -z "$CHROOT_NAME" ]
then
  if [ "$#" -gt 0 ]
  then CHROOT_NAME="$*"
  else CHROOT_NAME="`ls "$CHROOT_LOC" 2>/dev/null`"
  fi
fi
###
### Display 'croutonversion', 'architecture' and optionally other info.
if [ "$DISPLAY_ALL" = 'y' ]
then
  for EACH in $CHROOT_NAME
  do
    if [ ! -d "$CHROOT_LOC/$EACH" ]
    then
      error 1 "${Light_Red}Sorry, no chroot named: $EACH${C0}"
      continue
    fi
    (
    echo '----------------------------------------------------------------------' 1>&2
    echo "chroot name: $EACH" 1>&2
    sudo enter-chroot -c $CHROOT_LOC -n $EACH -x /usr/local/bin/croutonversion $UPDATE 2>&1 | grep -v -e ^Unmount -e ^Entering
    )
  done
elif [ "$DISPLAY_ALL" = 'n' ]
then
  for EACH in $CHROOT_NAME
  do
    if [ ! -d "$CHROOT_LOC/$EACH" ]
    then
      error 1 "${Light_Red}Sorry, no chroot named: $EACH${C0}"
      continue
    fi
    echo '----------------------------------------------------------------------' 1>&2
    vers="`grep ^VERSION $CHROOT_LOC/$EACH/usr/local/bin/croutonversion|cut -d= -f2 2>&1`"
    arch="`grep ^ARCH    $CHROOT_LOC/$EACH/usr/local/bin/croutonversion|cut -d= -f2 2>&1`"
    if [ -z "$arch" ]; then echo "chroot name: $EACH - version: $vers" 1>&2; fi
    if [ -n "$arch" ]; then echo "chroot name: $EACH - version: $vers - architecture: $arch" 1>&2; fi
  done
fi
echo '----------------------------------------------------------------------' 1>&2

NOTE: Copied latest 'private' version to 'public' area and added version tracking and version history option.
Also, added detection of and compliance with CROUTON partition in @drinkcat's 'separate_partition branch'.

Regretfully, 'crv -u (chroot-name)' is still broken :(