I want to write to a file in the home directory, so I tried the following command:
:call writefile(["foo"], "~/event.log", "a")
But I got an error:
E482: Can't create file ~/event.log
I am pretty sure that I have write permission for my home directory (of course), and there is not a file with the same name at the specified path.
If I change the destination path to the current path, it works.
Does anyone know what the problem is?
The tilde is only treated specially if it's used in commands like :w ~/event.log. When used in a string that is passed to a function -- even if this function treats the string argument as a file name -- it has no special meaning. You have to take care of the expansion of the tilde to the home directory yourself.
Vim has an expand() function that can be used for this. So one way to correctly write a file in your home directory is to execute the following command:
call writefile(["foo"], expand("~/event.log"), "a")
As Jürgen Krämer said, '~' string won't be interpreted by most vim functions.
Thus, when receiving the string from elsewhere, we may indeed need to expand() the tilde. However, when directly working on hardcoded pathnames as in your MWE, we can also use $HOME as in
call writefile(['foo'], $HOME.'/event.log'), 'a')
