diff --git a/run-validation.sh b/run-validation.sh
index 8d0fd9d0b7..3193123596 100755
--- a/run-validation.sh
+++ b/run-validation.sh
@@ -68,7 +68,7 @@ for modeldir in "$ns_base_path/validation/"*; do
     fi
 done
 
-unset ns_refresh_cache
+unset ns_cache_refresh
 unset ns_validation_output_format
 
 while [ -n "$1" ]; do
@@ -102,7 +102,7 @@ while [ -n "$1" ]; do
             models="$models $1"
             ;;
         -r | --refresh )
-            ns_refresh_cache="-r"
+            ns_cache_refresh=1
             ;;
         -* | --* )
             argerror "unknown option '$1'"
@@ -124,31 +124,48 @@ ns_prefix=$(full_path "$ns_prefix")
 
 source "$ns_base_path/scripts/environment.sh"
 default_environment
-export ns_validation_output_format
+
+export ns_cache_refresh
+
+# Add common/bin scripts to our path (used for git-repo-hash, pathsub).
+export PATH="$ns_base_path/common/bin${PATH:+:}$PATH"
 
 # TODO: this has to go into the configuration environment setup scripts
 export ARB_NUM_THREADS=$[ $ns_threads_per_core * $ns_cores_per_socket ]
 
-msg "---- Platform ----"
-msg "platform:          $ns_system"
-msg "cores per socket:  $ns_cores_per_socket"
-msg "threads per core:  $ns_threads_per_core"
-msg "threads:           $ARB_NUM_THREADS"
-msg "sockets:           $ns_sockets"
-msg "mpi:               $ns_with_mpi"
+info "---- Platform ----"
+info "platform:          $ns_system"
+info "cores per socket:  $ns_cores_per_socket"
+info "threads per core:  $ns_threads_per_core"
+info "threads:           $ARB_NUM_THREADS"
+info "sockets:           $ns_sockets"
+info "mpi:               $ns_with_mpi"
 echo
 
-msg "---- Validation ----"
-echo
+info "---- Validation ----"
+
+# Colour highlight shortcuts:
+red=${tcol[hi_red]}
+green=${tcol[hi_green]}
+cyan=${tcol[hi_cyan]}
+nc=${tcol[reset]}
+
+# Grab git repo hash and install timestamp for substitution in output directories below.
+# TODO: Move this sort of thing into a config/common_env.sh script at install time?
+repo_hash=$(git-repo-hash ${ns_base_path})
+repo_hash_short=$(git-repo-hash --short ${ns_base_path})
+ns_timestamp=$(< "$ns_build_path/timestamp")
+ns_sysname=$(< "$ns_build_path/sysname")
 
 for sim in $sims; do
+    echo
     sim_env="$ns_prefix/config/env_$sim.sh"
     if [ ! -f "$sim_env" ]; then
-        echo "Simulator $sim has not been locally installed, skipping."
+        info "Simulator $sim has not been locally installed, skipping."
         continue
     fi
 
-    echo "Running validation for $sim:"
+    info "Running validation for $sim:"
 
     for model in $models; do
         param=""
@@ -160,18 +177,54 @@ for sim in $sims; do
 
         model_path="$ns_base_path/validation/$basemodel"
         if [ ! -x "$model_path/run" ]; then
-            echo "Missing run file for model $basemodel, skipping."
+            info "Missing run file for model $basemodel, skipping."
             continue
         fi
 
         if [ ! -r "$model_path/$param.param" ]; then
-            echo "Missing parameter file $param.param for model $basemodel, skipping."
+            info "Missing parameter file $param.param for model $basemodel, skipping."
             continue
         fi
 
+        outdir=$(pathsub --base="$ns_validation_output" \
+            T="$ns_timestamp" S="$ns_sysname" H="$repo_hash" h="$repo_hash_short" \
+            s="$sim" m="$basemodel" p="$param" \
+            -- \
+            "${ns_validation_output_format:-%s/%m/%p}")
+
+        mkdir -p "$outdir" || exit_on_err "run-validation.sh: cannot create directory '$outdir'"
+
+        model_status="$outdir/status"
+        test_id="$sim $basemodel/$param"
+
+        # Run script exit codes:
+        #     0 => success: test passed.
+        #    96 => failure: test run but validation failed.
+        #    97 => missing: no implementation for given simulator.
+        # other => error: execution error.
+
         (
           source "$sim_env";
-          "$model_path/run" $ns_refresh_cache "$sim" "$param"
-        )
+          "$model_path/run" "$outdir" "$sim" "$param"
+        ) > "$outdir/run.out" 2> "$outdir/run.err"
+
+        case $? in
+            0 )
+                echo "$green[PASS]$nc $test_id"
+                echo pass > "$model_status"
+                ;;
+           96 )
+                echo "$red[FAIL]$nc $test_id"
+                echo fail > "$model_status"
+                ;;
+           97 )
+                echo "$cyan[MISSING]$nc $test_id"
+                echo missing > "$model_status"
+                ;;
+            * )
+                echo "$red[ERROR]$nc $test_id"
+                echo error > "$model_status"
+                ;;
+        esac
     done
 done
diff --git a/scripts/model_common.sh b/scripts/model_common.sh
index cdd081e8d0..1ce751b481 100755
--- a/scripts/model_common.sh
+++ b/scripts/model_common.sh
@@ -5,55 +5,43 @@
 # Requires PATH, PYTHONPATH and LD_LIBRARY_PATH to be already configured
 # for installed and common binaries, scripts and libraries.
 #
-# The following nsuite working paths are also required:
-#     ns_validation_output
-#     ns_cache_path
+# The following nsuite variables are used:
+#     ns_cache_path     (required)
+#     ns_cache_refresh  (optionally set)
 
 function die {
     echo "$@" >&2; exit 1
 }
 
+function exit_model_fail { exit 96; }
+function exit_model_missing { exit 97; }
+
 # Sets model_name, model_sim and model_param from arguments, provided in
 # this order.
 #
-# Creates if required output dir and cache dir.
-#
-# Sets variables model_output_dir, model_cache_dir, model_param_data
-# and model_status_path.
+# Computes and sets variables model_cache_dir, model_param_data.
+# Creates cache directory if not present.
 
 function model_setup {
-    if [ -z "$ns_validation_output" -o -z "$ns_cache_path" ]; then
+    if [ -z "$ns_cache_path" ]; then
         echo "error: missing required ns_ path variables"
         exit 1
     fi
 
     model_name="$1"
-
-    model_refresh=""
-    if [ "$2" = "-r" ]; then model_refresh="-r"; shift; fi
-
     model_sim="$2"
     model_param="$3"
 
     model_cache_dir="$ns_cache_path/$model_name"
     mkdir -p "$model_cache_dir" || die "$model_name: cannot create directory '$model_cache_dir'"
 
-    local -a fmtkeys
-    fmtkeys=("T=$ns_timestamp" "S=$ns_sysname" "s=$model_sim" "m=$model_name" "p=$model_param")
-    fmtkeys+=("H=$(git-repo-hash)" "h=$(git-repo-hash --short)")
-
-    model_output_dir=$(pathsub --base="$ns_validation_output" "${fmtkeys[@]}" -- "${ns_validation_output_format:-%s/%m/%p}")
-
-    mkdir -p "$model_output_dir" || die "$model_name: cannot create directory '$model_output_dir'"
-
-    model_status_path="$model_output_dir/status"
-
     [ -r "${model_param}.param" ] || die "$model_name: unable to read parameter data '${pset}.param'"
     model_param_data=$(< ${model_param}.param)
 }
 
 # Print path to file if in CWD, or else relative to cache dir.
-# Return non-zero if not in cache dir either.
+# Return non-zero if not in cache dir, or if "$ns_cache_refresh" is
+# set to a non-empty string.
 
 function model_find_cacheable {
     file="$1"
@@ -63,47 +51,6 @@ function model_find_cacheable {
     else 
         local cached="$model_cache_dir/$file"
         echo "$cached"
-        return $([ -e "$cached" ])
-    fi
-}
-
-# Report pass/fail status to stdout based on argument,
-# zero => pass; non-zero => fail.
-
-function model_notify_pass_fail {
-    local white=$'\033[1;37m'
-    local green=$'\033[1;92m'
-    local light_red=$'\033[1;31m'
-    local nc=$'\033[0m'
-
-    if [ "$1" -eq 0 ]; then
-        echo "${green}[PASS]${nc} $model_sim $model_name/$model_param"
-    else
-        echo "${light_red}[FAIL]${nc} $model_sim $model_name/$model_param"
+        return $([ -z "$ns_cache_refresh" -a -e "$cached" ])
     fi
 }
-
-# Attempt to run given simulator-specific script, redirecting
-# stdout and stderr to files in $model_output_dir.
-#
-# Report if error or if implementation is missing.
-
-function model_try_run {
-    local light_red=$'\033[1;31m'
-    local magenta=$'\033[1;35m'
-    local nc=$'\033[0m'
-
-    impl="$1"
-    shift
-
-    if [ ! -x "./$impl" ]; then
-        echo "${magenta}[UNIMPLEMENTED]${nc} $model_sim $model_name/$model_param"
-        exit 0
-    fi
-
-    "./$impl" "${@}" > "$model_output_dir/run.out" 2> "$model_output_dir/run.err" || {\
-        echo "${light_red}[ERROR]${nc} $model_sim $model_name/$model_param"
-        exit 0
-    }
-}
-
diff --git a/scripts/util.sh b/scripts/util.sh
index 4e44dd2ea9..7316df37a7 100644
--- a/scripts/util.sh
+++ b/scripts/util.sh
@@ -1,29 +1,76 @@
+init_tcol() {
+    # Set global associative array 'tcol' with entries for the eight
+    # commonly supported colours plus entries for other highlight modes.
+    #
+    # Leave it empty if we're not attached to a tty.
+
+    unset tcol
+    declare -gA tcol
+
+    if [[ -t 1 ]]; then
+        local -a colname=(black red green yellow blue magenta cyan white)
+        for i in ${!colname[@]}; do tcol[${colname[$i]}]="$(tput setaf $i)"; done
+
+        # If we have 16+ colours, set high intensity versions of colours to these,
+        # otherwise reuse the standard 8.
+
+        if [[ $(tput colors) -ge 16 ]]; then
+            for i in ${!colname[@]}; do
+                let j=8+i
+                tcol[hi_${colname[$i]}]="$(tput setaf $j)";
+            done
+        else
+            for i in ${!colname[@]}; do tcol[hi_${colname[$i]}]="${tcol[${colname[$i]}]}"; done
+        fi
+
+        # Other entries:
+        tcol[reset]=$(tput sgr0) # reset all attributes
+        tcol[bold]=$(tput bold)  # bold
+        tcol[ul]=$(tput smul)    # underline
+        tcol[noul]=$(tput rmul)  # no underline
+        tcol[so]=$(tput smso)    # standout
+        tcol[noso]=$(tput rmso)  # no standout
+    fi
+}
+
+# Always initialize colours on sourcing of util.sh
+init_tcol
+
 # Print a message to stderr.
 # Output to stderr to help determine where in build script an error occurred.
 msg() {
-    local white='\033[1;37m'
-    local light_cyan='\033[1;36m'
-    local nc='\033[0m'
+    local white="${tcol[hi_white]}"
+    local light_cyan="${tcol[hi_cyan]}"
+    local nc="${tcol[reset]}"
 
     >&2 printf "${light_cyan}== ${nc} ${white}$*${nc}\n"
 }
 
 err() {
-    local white='\033[1;37m'
-    local light_red='\033[1;31m'
-    local nc='\033[0m'
+    local white="${tcol[hi_white]}"
+    local light_red="${tcol[hi_red]}"
+    local nc="${tcol[reset]}"
 
     >&2 printf "${light_red}== ERROR${nc} ${white}$*${nc}\n"
 }
 
 dbg() {
-    local white='\033[1;37m'
-    local green='\033[1;92m'
-    local nc='\033[0m'
+    local white="${tcol[hi_white]}"
+    local green="${tcol[hi_green]}"
+    local nc="${tcol[reset]}"
 
     >&2 printf "${green}==== ${nc} ${white}$*${nc}\n"
 }
 
+# Print a message to stdout following msg() formatting.
+info() {
+    local white="${tcol[hi_white]}"
+    local light_cyan="${tcol[hi_cyan]}"
+    local nc="${tcol[reset]}"
+
+    printf "${light_cyan}== ${nc} ${white}$*${nc}\n"
+}
+
 exit_on_error() {
     err "$*"
     exit 1
diff --git a/validation/rc-exp2syn-spike/run b/validation/rc-exp2syn-spike/run
index 3bbb5cb8df..a9dd095223 100755
--- a/validation/rc-exp2syn-spike/run
+++ b/validation/rc-exp2syn-spike/run
@@ -1,11 +1,18 @@
 #!/usr/bin/env bash
+# Invocation: run outputdir simname paramsetname
 
 # Change to script directory and attempt to find nsuite base directory.
+
 unset CDPATH
 cd "${BASH_SOURCE[0]%/*}"
 [ -n "$ns_base_path" ] || ns_base_path="$(cd ../..; pwd)"
 
-# Set up model paths and model_XXX variables.
+# Set up model paths,  model_XXX variables, and functions
+# exit_model_fail, exit_model_missing.
+
+outdir=$1
+shift
+
 source "$ns_base_path/scripts/model_common.sh"
 model_setup rc-exp2syn-spike "$@"
 
@@ -18,21 +25,24 @@ model_setup rc-exp2syn-spike "$@"
 # For CoreNEURON, voltage traces will be omitted; the pass/fail
 # test only looks at spike time differences.
 
-# Run sim-specific implementation with parameter data.
-outfile="$model_output_dir/run.nc"
-model_try_run "run-$model_sim" "$outfile" $model_param_data
+impl="./run-$model_sim"
+[ -x "$impl" ] || exit_model_missing
+
+outfile="$outdir/run.nc"
+"$impl" "$outfile" $model_param_data || exit 1
 
 # Generate reference data if required.
-reffile=$(model_find_cacheable "ref-${model_name}-${model_param}.nc")
-if [ $? -ne 0 -o -n "$model_refresh" ]; then 
-    ./generate-rc-exp2syn-spike "$reffile" $model_param_data
-fi
+
+reffile=$(model_find_cacheable "ref-${model_name}-${model_param}.nc") || \
+    ./generate-rc-exp2syn-spike "$reffile" $model_param_data || exit 1
 
 # Run comparison.
-deltafile="$model_output_dir/delta.nc"
-comparex "$outfile" --warn --ref "$reffile" --var spike -o "$deltafile"
+
+deltafile="$outdir/delta.nc"
+comparex "$outfile" --warn --ref "$reffile" --var spike -o "$deltafile" || exit 1
 
 # Get threshold from parameter data 'max_error'
+
 max_error=
 for param in $model_param_data; do
     if [[ "$param" =~ ^'max_error='(.*) ]]; then
@@ -44,5 +54,4 @@ if [ -z "$max_error" ]; then
     exit 1
 fi
 
-thresholdx "$deltafile" -e "spike.abserr<$max_error" > "$model_status_path"
-model_notify_pass_fail $?
+thresholdx "$deltafile" -e "spike.abserr<$max_error" || exit_model_fail
diff --git a/validation/rc-expsyn/run b/validation/rc-expsyn/run
index c3fc3ad5e1..24aeb786e2 100755
--- a/validation/rc-expsyn/run
+++ b/validation/rc-expsyn/run
@@ -1,27 +1,37 @@
 #!/usr/bin/env bash
+# Invocation: run outputdir simname paramsetname
 
 # Change to script directory and attempt to find nsuite base directory.
+
 unset CDPATH
 cd "${BASH_SOURCE[0]%/*}"
 [ -n "$ns_base_path" ] || ns_base_path="$(cd ../..; pwd)"
 
-# Set up model paths and model_XXX variables.
+# Set up model paths, model_XXX variables, and functions
+# exit_model_fail, exit_model_missing.
+
+outdir=$1
+shift
+
 source "$ns_base_path/scripts/model_common.sh"
 model_setup rc-expsyn "$@"
 
 # Run sim-specific implementation with parameter data.
-outfile="$model_output_dir/run.nc"
-model_try_run "run-$model_sim" "$outfile" $model_param_data
+
+impl="./run-$model_sim"
+[ -x "$impl" ] || exit_model_missing
+
+outfile="$outdir/run.nc"
+"$impl" "$outfile" $model_param_data || exit 1
 
 # Generate reference data if required.
-reffile=$(model_find_cacheable "ref-${model_name}-${model_param}.nc")
-if [ $? -ne 0 -o -n "$model_refresh" ]; then 
-    ./generate-rc-expsyn "$reffile" $model_param_data
-fi
+
+reffile=$(model_find_cacheable "ref-${model_name}-${model_param}.nc") || \
+    ./generate-rc-expsyn "$reffile" $model_param_data || exit 1
 
 # Run comparison.
-deltafile="$model_output_dir/delta.nc"
-comparex "$outfile" --warn --ref "$reffile" --interpolate time -o "$deltafile"
 
-thresholdx "$deltafile" -e "voltage.relerr.lb<0.01" > "$model_status_path"
-model_notify_pass_fail $?
+deltafile="$outdir/delta.nc"
+comparex "$outfile" --warn --ref "$reffile" --interpolate time -o "$deltafile" || exit 1
+
+thresholdx "$deltafile" -e "voltage.relerr.lb<0.01" || exit_model_fail