Merge pull request #216 from sourceryinstitute/remove-bashism

Remove bashism from install.sh

Author: milancurcic

install.sh

@@ -19,14 +19,14 @@ else
   fi
 fi
 
-if [[ -x "$install_path/fpm" ]]; then
+if [ -x "$install_path/fpm" ]; then
   echo "Overwriting existing fpm installation in $install_path"
 fi
 
 cd bootstrap
 stack install
 
-if [[ -x "$install_path/fpm" ]]; then
+if [ -x "$install_path/fpm" ]; then
   echo "fpm installed successfully to $install_path"
 else
   echo "fpm installation unsuccessful: fpm not found in $install_path"