Only add source lines to shell rc file if not already there

Author: connesy

install.sh

@@ -1,6 +1,7 @@
 #!/usr/bin/env bash
 _src_dir="${PWD}/src/venv-cli"
 _install_dir="/usr/local/share/venv"
+_source_comment="# Source function script for 'venv' command"
 
 set -e
 
@@ -18,9 +19,13 @@ install_common() {
     sudo cp "${completion_file}" "${completion_target}"
   fi
 
-  # Append line to the shell config file to source the script
-  echo -e "\n# Source function script for 'venv' command" >> "${rcfile}"
-  echo ". ${_install_dir}/venv" >> "${rcfile}"
+  # If line does not already exist in the rc file,
+  # append line to the shell config file to source the venv-cli script
+  if ! command grep -q "${_source_comment}" "${rcfile}"; then
+    echo "${_source_comment}" >> "${rcfile}"
+    echo "source ${_install_dir}/venv" >> "${rcfile}"
+  fi
+
   { set +x; } 2>/dev/null
 }
 
@@ -40,8 +45,10 @@ install_zsh() {
   echo "Command completions currently not supported for zsh"
 
   install_common "${rcfile}"
-  echo "fpath+=( ${_install_dir} )" >> "${rcfile}"
-  echo "autoload -Uz venv" >> "${rcfile}"
+  if ! command grep -q "${_source_comment}" "${rcfile}"; then
+    echo "fpath+=( ${_install_dir} )" >> "${rcfile}"
+    echo "autoload -Uz venv" >> "${rcfile}"
+  fi
 }
 
 main() {