fake a filename for filetype detection when reading from stdin

Question

When reading from stdin with something like fancy-command | vim -R -, vim does not detect the filetype (i.e. set filetype prints filetype=). When I know the right vim filetype, I can provide it from the command line (or from within vim) with fancy-command | vim -R +'set ft=cpp' -.

Now, that pipe might be in a shell script e.g. in conjunction with git show <commit hash>:<path>, such that I don't want to hardcode cpp as filetype. I have thought about just taking the end of <path> and provide it to ft=, but I expect this to fail (CMakeLists.txt are not identified by their suffix).

So what I'd like to do is run vim's filetype detect but with a pretended filename when vim is actually reading from stdin.

Answer 1

You could try something like the following:

#!/bin/bash

file=$1

cat $file | vim -c "doautocmd BufRead $file" -

This will run the autocommands that would normally run, when you would open a file with the given name. This includes filetype detection.

To my surprise, this also works when the file name contains a space.

The name is only used to run the autocommands, the name of the loaded buffer is not changed (it still is [No Name]).