From ee869a9584be57efecd8b836c35d3c01f91c973d Mon Sep 17 00:00:00 2001
From: Manuel Streuhofer <manuel@streuhofer.net>
Date: Thu, 25 Jan 2018 10:35:53 +0100
Subject: [PATCH] templater.sh: use perl if available (#98)

---
 src/templater.sh | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/src/templater.sh b/src/templater.sh
index eab35a1..7882387 100755
--- a/src/templater.sh
+++ b/src/templater.sh
@@ -39,12 +39,17 @@ function templater() {
     exit 1
   fi
 
-  cp -f "${templateSrc}" "${templateDst}"
-  for var in $(env |awk -F= '{print $1}' |grep -E '^(_[A-Z0-9_]+|[A-Z0-9][A-Z0-9_]*)$'); do
-    sed -i.bak -e "s#\${${var}}#${!var//#/\\#/}#g" "${templateDst}"
-    # this .bak dance is done for BSD/GNU portability: http://stackoverflow.com/a/22084103/151666
-    rm -f "${templateDst}.bak"
-  done
+  if [[ "$(command -v perl)" ]]; then
+    perl -p -e 's/\$\{(\w+)\}/(exists $ENV{$1} ? $ENV{$1} : "\${$1}")/eg' < "${templateSrc}" > "${templateDst}"
+  else
+    cp -f "${templateSrc}" "${templateDst}"
+
+    for var in $(env |awk -F= '{print $1}' |grep -E '^(_[A-Z0-9_]+|[A-Z0-9][A-Z0-9_]*)$'); do
+      sed -i.bak -e "s#\${${var}}#${!var//#/\\#/}#g" "${templateDst}"
+      # this .bak dance is done for BSD/GNU portability: http://stackoverflow.com/a/22084103/151666
+      rm -f "${templateDst}.bak"
+    done
+  fi
 
   # cat "${templateDst}"