Update makenew.sh to work on Unix and Mac

Author: razor-x

makenew.sh

@@ -4,7 +4,18 @@ set -e
 set -u
 
 find_replace () {
-  git ls-files -z | xargs -0 sed -i "$1"
+  git grep --cached -Il '' | xargs sed -i.sedbak -e "$1"
+  find . -name "*.sedbak" -exec rm {} \;
+}
+
+sed_insert () {
+  sed -i.sedbak -e "$2\\"$'\n'"$3"$'\n' $1
+  rm $1.sedbak
+}
+
+sed_delete () {
+  sed -i.sedbak -e "$2" $1
+  rm $1.sedbak
 }
 
 check_env () {
@@ -37,15 +48,15 @@ makenew () {
   read -p '> GitHub user or organization name: ' mk_user
   read -p '> GitHub repository name: ' mk_repo
 
-  sed -i -e '3d;23,108d;245,248d' README.md
+  sed_delete README.md '3d;23,108d;245,248d'
 
   find_replace "s/0\.0\.0/${mk_version}/g"
   find_replace "s/2016 Evan Sosenko/${mk_year} ${mk_owner}/g"
   find_replace "s/Evan Sosenko/${mk_author}/g"
   find_replace "s/makenew\/nvimrc/${mk_user}\/${mk_repo}/g"
 
   mk_attribution='> Built from [makenew/nvimrc](https://github.com/makenew/nvimrc).'
-  sed -i -e "6i ${mk_attribution}\n" README.md
+  sed_insert README.md '6i' "${mk_attribution}\n"
 
   echo
   echo 'Replacing boilerplate.'