Every time when I run a brew command, it will give me several error lines at the beginning. I can't understand what's going on here. Can anyone tell me how I can get rid of the error? 

```
brew
/bin/sh: __rvm_ruby_string_find: line 8: syntax error near unexpected token `('
/bin/sh: __rvm_ruby_string_find: line 8: ` ruby-+([1-9]) | ruby-+([1-9]).+([0-9]) | ruby-1.+([1-9]).+([0-9]) | jruby-[19]*)'
/bin/sh: error importing function definition for `__rvm_ruby_string_find'
/bin/sh: __rvm_project_ruby_env_load_parse_file: line 9: syntax error near unexpected token `('
/bin/sh: __rvm_project_ruby_env_load_parse_file: line 9: ` __rvm_read_lines __variables <( { cat "$1"; echo ""; } | __rvm_sed "${__sed_commands[@]}" )'
/bin/sh: error importing function definition for `__rvm_project_ruby_env_load_parse_file'
/bin/sh: __rvm_remove_without_gems: line 2: syntax error near unexpected token `('
/bin/sh: __rvm_remove_without_gems: line 2: ` __rvm_read_lines __gems_to_remove <('
/bin/sh: error importing function definition for `__rvm_remove_without_gems'

```

Now I found if I run an illegal command for ruby, it gives me a same error message. So is it because my version problem?
![enter image description here](https://i.stack.imgur.com/OyuTv.png)