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Quick peak at files

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created 2006 · complexity intermediate · author Suresh Govindachar · version 6.0


In an operating system's command-line terminal, one can get a quick peak at a file using commands such as more, cat, head etc. In Vim, one way to peak at a file would be to open it in a new buffer -- but there is a way to peak at a file from Vim without having to open it in a buffer, browse it and close the buffer -- one can just view it in Vim's command line! This mode of viewing is facilitated by Vim version 7's support for scrolling (see :help new-scroll-back).

So to peak at a file, we just echo its contents (:help :echo).

Simple implementation:

One way to implement the idea would be:

:new|r <file_name>|1d|exec 'normal "ayG'|q!|echo @a

One could also do :echo system('cat foo.bat'), but we are trying to avoid explicit system calls. In version 7, Vim supports readfile(). But the result of readfile() is an array of lines -- and these lines would need to be joined to enable viewing; so we have:

:echo join(readfile('foo.bat'), "\n")

Applications:

Here are two applications that build on the idea presented here.

Yasuhiro Matsumoto's calendar utility script#52 is written to display the calendar in a buffer. For a quick peak at the calendar, one can modify the plugin to support echoing the calendar in Vim's command line, and make a simple map (such as of a RightMouse click) to trigger the display on the command line.

I have the following in my vimfiles\after\ftplugin\index.vim to speed up previewing emails using my mail user agent utility script#1052.

if(v:version < 700)
  nnoremap <buffer> <Space> :exec "let @a='r '.expand('%:p:h').'/'.substitute(
        \getline('.'),
  '\\(^.*\|\\s*\\)\\\|\\(\\s\\s*$\\)',
  '',
  'g')
        \\\|new\\|@a\\|1d\\|
        \silent exec 'normal\ d}\"ayG'\\|q!\\|echo\ @a"<CR>
else
  nnoremap <buffer> <Space> :exec "let alist=readfile(expand('%:p:h').'/'.
        \substitute(getline('.'),
  '\\(^.*\|\\s*\\)\\\|\\(\\s\\s*$\\)',
  '',
  'g')
        \)\\|
        \while(remove(alist, 0) != '')
        \\\|endwhile
        \\\|echo\
        \substitute(getline('.'),
  '\\(^.*\|\\s*\\)\\\|\\(\\s\\s*$\\)',
  '',
  'g').\"\n\n\"
        \\\|echo join(alist,\"\n\")"<CR>
endif

CommentsEdit

Most normal mode commands have a command line counterpart. For example,

exec 'normal "ayG'

could be replaced by

%yank a

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