Enhance the variable replacement

Add ability to also run shell commands contained in the sys.config.
E.g.:

# In this example the node name defaults to name of the release
# and can be overriden at run-time, appended with current year
$ head -1 vm.args
-sname ${NODE_NAME:-$REL_NAME}$(date +%Y)

# If the $NAME is 'abc2015', and hostname is 'MyHost', below the 'node'
# parameter gets set to 'Abc2015@myhost'
$ grep node sys.config
   {node, $(echo ${NAME^})@${HOSTNAME,,}}

1 files changed, 14 insertions, 12 deletions

diff --git a/priv/templates/extended_bin b/priv/templates/extended_bin
index 4a29d44..b6eb297 100755
--- a/priv/templates/extended_bin
+++ b/priv/templates/extended_bin
@@ -6,7 +6,7 @@ SCRIPT=$(readlink -f $0 || true)
 [ -z $SCRIPT ] && SCRIPT=$0
 SCRIPT_DIR="${SCRIPT%/*}"
 RELEASE_ROOT_DIR="${SCRIPT_DIR%/*}"
-REL_NAME="{{ rel_name }}"
+export REL_NAME="{{ rel_name }}"
 REL_VSN="{{ rel_vsn }}"
 ERTS_VSN="{{ erts_vsn }}"
 CODE_LOADING_MODE="${CODE_LOADING_MODE:-embedded}"
@@ -90,7 +90,7 @@ relx_start_command() {
 # Replace environment variables
 relx_replace_os_vars() {
     awk '{
-        while(match($0,/\$\{[^{}]+?\}/)) {
+        while(match($0,/\$[{(][^{}()]+?[})]/)) {
             s=RSTART; n=RLENGTH;
             v0=substr($0,0,s-1); v1=substr($0,s,n); v2=substr($0,n+s,length($0)-s-n+1)
             "echo "v1|getline v; $0=v0 v v2
@@ -126,15 +126,10 @@ if [ -z "$RELX_CONFIG_PATH" ]; then
     fi
 fi
 
-if [ $RELX_REPLACE_OS_VARS ]; then
-    IN=$RELX_CONFIG_PATH
-    OUT=${IN##*/}
-    RELX_CONFIG_PATH=${IN%.*}.2.${OUT##*.}
-    relx_replace_os_vars ${IN} ${RELX_CONFIG_PATH}
-fi
-
 # Extract the target node name from node.args
-NAME_ARG=( $(eval echo $(egrep '^-s?name' "$VMARGS_PATH" || true)) )
+# Do this BEFORE possible variable replacement, so that $NAME is available
+# in the replacement phase if needed
+NAME_ARG=( $(egrep '^-s?name' "$VMARGS_PATH" || true) )
 if [ -z "${NAME_ARG[*]}" ]; then
     echo "vm.args needs to have either -name or -sname parameter."
     exit 1
@@ -142,12 +137,19 @@ fi
 
 # Extract the name type and name from the NAME_ARG for REMSH
 NAME_TYPE="${NAME_ARG[0]}"
-NAME="${NAME_ARG[1]}"
+export NAME="${NAME_ARG[*]:1}"
+
+if [ $RELX_REPLACE_OS_VARS ]; then
+    IN=$RELX_CONFIG_PATH
+    OUT=${IN##*/}
+    RELX_CONFIG_PATH=${IN%.*}.2.${OUT##*.}
+    relx_replace_os_vars ${IN} ${RELX_CONFIG_PATH}
+fi
 
 PIPE_DIR="${PIPE_DIR:-/tmp/erl_pipes/$NAME/}"
 
 # Extract the target cookie
-COOKIE_ARG=( $(eval echo $(grep '^-setcookie' "$VMARGS_PATH" || true)) )
+COOKIE_ARG=( $(grep '^-setcookie' "$VMARGS_PATH" || true) )
 if [ -z "${COOKIE_ARG[*]}" ]; then
     echo "vm.args needs to have a -setcookie parameter."
     exit 1