gist for https://attonblog.blogspot.com/2019/09/neovim-sudo-without-plugin.html

fedora-askpass.txt

[root@9015bf44beee /]# dnf search askpass
Fedora Modular 30 - x86_64                                      1.5 MB/s | 1.9 MB     00:01
Fedora Modular 30 - x86_64 - Updates                            2.0 MB/s | 2.8 MB     00:01
Fedora 30 - x86_64 - Updates                                    5.0 MB/s |  23 MB     00:04
Fedora 30 - x86_64                                              5.2 MB/s |  61 MB     00:11
Last metadata expiration check: 0:00:01 ago on Sat Aug 31 00:41:37 2019.
=============================== Name & Summary Matched: askpass ================================
lxqt-openssh-askpass-l10n.x86_64 : Translations for lxqt-openssh-askpass
lxqt-openssh-askpass.x86_64 : Askpass openssh transition dialog for LXQt desktop suite
==================================== Name Matched: askpass =====================================
R-askpass.x86_64 : Safe Password Entry for R, Git, and SSH
ksshaskpass.x86_64 : A ssh-add helper that uses kwallet and kpassworddialog
openssh-askpass.x86_64 : A passphrase dialog for OpenSSH and X
x11-ssh-askpass.x86_64 : A passphrase dialog for X and not only for OpenSSH

fedora-ksshaskpass.txt

# dnf install -y ksshaskpass
# find . -name '*askpass*' -type f
./etc/xdg/plasma-workspace/env/ksshaskpass.sh
./usr/share/locale/en_GB/LC_MESSAGES/ksshaskpass.mo
./usr/bin/ksshaskpass
/usr/bin/ksshaskpass
# /usr/bin/ksshaskpass --help
qt.qpa.xcb: could not connect to display
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, xcb.

Aborted
# dnf remove -y ksshaskpass

fedora-openssh-askpass.txt

# dnf install -y openssh-askpass
# find . -name '*askpass*' -type f
./etc/profile.d/gnome-ssh-askpass.csh
./etc/profile.d/gnome-ssh-askpass.sh
./usr/libexec/openssh/gnome-ssh-askpass
# /usr/libexec/openssh/gnome-ssh-askpass
(gnome-ssh-askpass:112): Gtk-WARNING **: 00:51:47.072: cannot open display:
# /usr/libexec/openssh/gnome-ssh-askpass --help
(gnome-ssh-askpass:113): Gtk-WARNING **: 00:52:10.596: cannot open display:
# dnf remove -y openssh-askpass

fedora-x11-ssh-askpass.txt

# dnf install -y x11-ssh-askpass
# find . -name '*askpass*' -type f
./etc/profile.d/x11-ssh-askpass.sh
./etc/profile.d/x11-ssh-askpass.csh
./usr/libexec/openssh/x11-ssh-askpass
# /usr/libexec/openssh/x11-ssh-askpass
Error: Can't open display:
# /usr/libexec/openssh/x11-ssh-askpass --help
Error: Can't open display:
# dnf remove -y x11-ssh-askpass

sudo_write_current_buffer.vim

function! s:sudo_write_current_buffer() abort
    if has('nvim')
        let s:askpass_path = '/tmp/askpass'
        let s:password     = inputsecret("Enter Password: ")
        let $SUDO_ASKPASS  = s:askpass_path

        try
            call delete(s:askpass_path)
            call writefile(['#!/bin/sh'],                 s:askpass_path, 'a')
            call writefile(["echo '" . s:password . "'"], s:askpass_path, 'a')
            call setfperm(s:askpass_path, "rwx------")
            write ! sudo -A tee % > /dev/null
        finally
            unlet s:password
            call delete(s:askpass_path)
        endtry
    else
        write ! sudo tee % > /dev/null
    endif
endfunction
command! SudoWriteCurrentBuffer call s:sudo_write_current_buffer()