How do I send the contents of my buffer to a shell command without replacing the text?

Explanation

The :w !{cmd} command writes the buffer contents to the stdin of an external shell command without modifying the buffer or saving to disk. This is fundamentally different from :%!{cmd} which replaces the buffer with the command's output — :w !{cmd} leaves your buffer untouched and just displays the command's output in Vim's command area.

How it works

• :w normally writes the buffer to a file, but when followed by !{cmd}, it pipes the buffer contents to the shell command's stdin instead
• The buffer itself is not modified — the text stays exactly as it is
• The command's stdout is displayed below the status line
• You can use a range to send only specific lines: :1,10w !wc -l sends just lines 1-10

Note the space between w and !. Without the space, :w! is a force-write to disk — a completely different command.

Example

Count the words in your buffer without leaving Vim:

:w !wc -w

Vim displays something like:

     342

Run the buffer as a script:

:w !bash

Send selected lines to a command — visually select some lines, then:

:'<,'>w !python3

This executes just the selected lines as a Python script.

Copy the entire buffer to the system clipboard (on macOS):

:w !pbcopy

Tips

• Remember: :w !cmd pipes to a command, :%!cmd filters the buffer through a command (replacing contents). The space matters!
• Use :w !diff - % to see the diff between the buffer's current state and the saved file on disk — the - reads from stdin (the buffer) and % is the filename
• :w !sudo tee % is the classic trick for writing to a file you opened without root permissions
• Combine with ranges for targeted operations: :.w !bash executes only the current line as a shell command
• The output is shown in Vim's message area — press <CR> to dismiss it and return to editing
• Use :silent w !cmd to suppress the output if you don't need to see it