feat: substitute environment into a file using envsubst

feat  build_file  no added file comment by default use -f to enable

modules/utility/file.lib

@@ -14,10 +14,58 @@ isFile() {
     fi
 }
 
+                                                                                # env_file_pretty () {
+  
+# }
+
+# https://www.baeldung.com/linux/envsubst-command
+env_subs_file () {
+ module_load helpers 
+ local input; local fenv; local all
+ [[ $1 == "-a" ]] && all=true && shift 1
+ input=$1
+ fenv=$2
+ [[ ! $input ]] && iecho "nothing was passed to merge with environment" && return 1
+ [[ -f "$input" ]] && input=$(cat "$input")
+ [[ ! $(echo $input | grep -F "$") ]] && iecho "nothing to merge in $1" && return 2
+ if [[ ($2 && ! -f $2) ]]; then
+  iecho "no enviroment file at $2" && return 3
+ else 
+  # [[ $all ]] && export_file $fenv && unset fenv
+  if [[ $all ]]; then
+   fenv="/tmp/$USER/_tenvf" 
+   # put quotes around values to avoid issues
+   env | sed 's/\(=[[:blank:]]*\)\(.*\)/\1"\2"/' > $fenv 
+   cat $2 | sed 's/\(=[[:blank:]]*\)\(.*\)/\1"\2"/' | sed 's/\s*=\s*/=/g'
+   return
+   cat "$2" | sed 's/\(=[[:blank:]]*\)\(.*\)/\1"\2"/' >> $fenv
+  fi  
+ fi
+ if [[ $fenv ]]; then
+    (set -a;source "$fenv" ;set +a; echo -e "$input" | envsubst "$(printf '${%s} ' $(cat "$fenv" | cut -d'=' -f1) )")  
+  else
+      echo -e "$input" | envsubst "$(printf '${%s} ' $(env | cut -d'=' -f1) )" 
+ fi 
+ [[ $all ]] && rm -f  $fenv
+# [[ $all ]] && unset_file $2
+}
+
+
+#  shift 1
+#  input=$1
+#  set -a;. $2 ;set +a;
+#  echo env file is now $2
+#  fi
+
 build_file () {
+  # local file
+  # echo build file $1 $2
+  [[ $1 == "-f" ]] && file=true && shift 1
   [[ -f "$2" ]] || (iecho "output file $2 does not exist";return 1)
   if [[ -f "$1" ]]; then
-    echo -e "\n####### ADDED $1 ########" >> $2
+  # echo $1
+    [[ $file ]] && echo -e "\n####### ADDED $1 ########" >> $2
+    # remove comment lines,  remove blank last line
     cat "$1" | sed '/^\s*#/d' | sed '/^$/{:a;N;s/\n$//;ta}' >> $2
   else iecho "no such file $1 to append"
   fi

modules/utility/iecho.func

@@ -1,6 +1,7 @@
 #!/bin/bash
 iecho () {
 [[ ! -z "$PS1" ]] && echo $1
+return 0
 }
 
 #   no way to tell if sourced vs subshell