From ef88c20cdcfa2c3396ed7ce63915765fee088af6 Mon Sep 17 00:00:00 2001
From: sanmiguel <michael.coles@gmail.com>
Date: Tue, 17 May 2016 17:43:19 +0200
Subject: First draft PoC at tidier env wrangling

---
 kerl | 102 ++++++++++++-------------------------------------------------------
 1 file changed, 18 insertions(+), 84 deletions(-)

diff --git a/kerl b/kerl
index 58cc66e..a28657e 100755
--- a/kerl
+++ b/kerl
@@ -28,98 +28,32 @@ GREP_OPTIONS=''
 ERLANG_DOWNLOAD_URL="http://www.erlang.org/download"
 
 # Default values
-: ${OTP_GITHUB_URL:="https://github.com/erlang/otp"}
-: ${KERL_BASE_DIR:="$HOME"/.kerl}
 : ${KERL_CONFIG:="$HOME"/.kerlrc}
+
+# Take a snapshot of the env
+_FULL_ENV="$(env)"
+# By restoring the env after .kerlrc, we can set system defaults in .kerlrc
+# but session defaults in env.
+
+# source the config file if available
+if [ -f "$KERL_CONFIG" ]; then . "$KERL_CONFIG"; fi
+
+# Restore the env over .kerlrc's contents
+echo "$_FULL_ENV" | while read -r e ; do
+                        # This doesn't work, probably because eval is a subshell
+                        eval "export \"$e\""
+                    done
+
+# By holding defaults until now, we are sure not to clobber settings from env or .kerlrc
+: ${KERL_BASE_DIR:="$HOME"/.kerl}
 : ${KERL_DOWNLOAD_DIR:="${KERL_BASE_DIR:?}"/archives}
 : ${KERL_BUILD_DIR:="${KERL_BASE_DIR:?}"/builds}
 : ${KERL_GIT_DIR:="${KERL_BASE_DIR:?}"/gits}
-
-if [ -n "$OTP_GITHUB_URL" ]; then
-    _OGU="$OTP_GITHUB_URL"
-fi
-if [ -n "$KERL_CONFIGURE_OPTIONS" ]; then
-    _KCO="$KERL_CONFIGURE_OPTIONS"
-fi
-if [ -n "$KERL_CONFIGURE_APPLICATIONS" ]; then
-    _KCA="$KERL_CONFIGURE_APPLICATIONS"
-fi
-if [ -n "$KERL_CONFIGURE_DISABLE_APPLICATIONS" ]; then
-    _KCDA="$KERL_CONFIGURE_DISABLE_APPLICATIONS"
-fi
-if [ -n "$KERL_SASL_STARTUP" ]; then
-    _KSS="$KERL_SASL_STARTUP"
-fi
-if [ -n "$KERL_DEPLOY_SSH_OPTIONS" ]; then
-    _KDSSH="$KERL_DEPLOY_SSH_OPTIONS"
-fi
-if [ -n "$KERL_DEPLOY_RSYNC_OPTIONS" ]; then
-    _KDRSYNC="$KERL_DEPLOY_RSYNC_OPTIONS"
-fi
-if [ -n "$KERL_INSTALL_MANPAGES" ]; then
-    _KIM="$KERL_INSTALL_MANPAGES"
-fi
-if [ -n "$KERL_BUILD_PLT" ]; then
-    _KBPLT="$KERL_BUILD_PLT"
-fi
-if [ -n "$KERL_BUILD_DOCS" ]; then
-    _KBD="$KERL_BUILD_DOCS"
-fi
-if [ -n "$KERL_BUILD_BACKEND" ]; then
-    _KBB="$KERL_BUILD_BACKEND"
-fi
-OTP_GITHUB_URL=
-KERL_CONFIGURE_OPTIONS=
-KERL_CONFIGURE_APPLICATIONS=
-KERL_CONFIGURE_DISABLE_APPLICATIONS=
-KERL_SASL_STARTUP=
-KERL_DEPLOY_SSH_OPTIONS=
-KERL_DEPLOY_RSYNC_OPTIONS=
-KERL_INSTALL_MANPAGES=
-KERL_BUILD_PLT=
-KERL_BUILD_DOCS=
-KERL_BUILD_BACKEND=
+: ${OTP_GITHUB_URL:="https://github.com/erlang/otp"}
 
 # ensure the base dir exists
 mkdir -p "$KERL_BASE_DIR" || exit 1
 
-# source the config file if available
-if [ -f "$KERL_CONFIG" ]; then . "$KERL_CONFIG"; fi
-
-if [ -n "$_OGU" ]; then
-    OTP_GITHUB_URL="$_OGU"
-fi
-if [ -n "$_KCO" ]; then
-    KERL_CONFIGURE_OPTIONS="$_KCO"
-fi
-if [ -n "$_KCA" ]; then
-    KERL_CONFIGURE_APPLICATIONS="$_KCA"
-fi
-if [ -n "$_KCDA" ]; then
-    KERL_CONFIGURE_DISABLE_APPLICATIONS="$_KCDA"
-fi
-if [ -n "$_KSS" ]; then
-    KERL_SASL_STARTUP="$_KSS"
-fi
-if [ -n "$_KDSSH" ]; then
-    KERL_DEPLOY_SSH_OPTIONS="$_KDSSH"
-fi
-if [ -n "$_KDRSYNC" ]; then
-    KERL_DEPLOY_RSYNC_OPTIONS="$_KDRSYNC"
-fi
-if [ -n "$_KIM" ]; then
-    KERL_INSTALL_MANPAGES="$_KIM"
-fi
-if [ -n "$_KBPLT" ]; then
-    KERL_BUILD_PLT="$_KBPLT"
-fi
-if [ -n "$_KBD" ]; then
-    KERL_BUILD_DOCS="$_KBD"
-fi
-if [ -n "$_KBB" ]; then
-    KERL_BUILD_BACKEND="$_KBB"
-fi
-
 if [ -z "$KERL_SASL_STARTUP" ]; then
     INSTALL_OPT=-minimal
 else
-- 
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