How to enable map command in vim?

Question

How to enable map command only when filetype is 'perl'?

something like:

if(&ft=='perl')
  map ,pt <ESC>:%! perltidy<CR>
endif

but it doesn't work.

Answer 1

I found the shorter way.

Add this line to your ~/.vimrc

au FileType perl nnoremap <buffer> _t <ESC>:%! perltidy<CR>

Answer 2

1. Create the file ~/.vim/after/ftplugin/perl.vim.

2. Put this line in that file:

   nnoremap <buffer> ,pt <ESC>:%! perltidy<CR>
   

Answer 3

I have below lines in my .vimrc. the first one sets the "tab" unit for any "perl" filetype and the second one runs perltidy with _t keyboard shortcut. THis many not get you the exact answer but surely should get you some pointers:

autocmd FileType perl set tabstop=4|set shiftwidth=4|set expandtab|set softtabstop=4
nnoremap <silent> _t :%!perltidy -q<Enter>
vnoremap <silent> _t :!perltidy -q<Enter>

I have been using these setting in my .vimrc for last 5+ years. The credit goes to whoever came up with these commands. I did not make above commands.