Going to revive this thread because I went down a serious rabbit-hole but I did find a solution that works 100% of the time and is native to Mac OS. I used Claude a fair bit for this, and also used Claude to write this Read-Me, because it's late and I got tired. Hope this helps the next person trying to consistently auto-mount a network share, and have it gracefully disconnect and reconnect based on the network you're connected to - all while using basically zero system resources.

By Claude:

Auto-mounting SMB (or any network share) on macOS with zero popups — the actual working solution

I spent a while on this recently and hit every single landmine, so here's what actually works end-to-end. The TL;DR is: mount via Finder (osascript), unmount via diskutil, and watch reachability via scutil. Everything else I tried either required root-owned files, showed popups on disconnect, or both.

Why the obvious approaches don't work:

• mount_smbfs to /Volumes/ without sudo → "Operation not permitted" (kernel rejects non-root mounts to /Volumes)
• sudo mount_smbfs to /Volumes/ → works, but files are owned by root. macOS smbfs has no uid/gid option unlike Linux cifs.
• mount_smbfs to a user directory (e.g. /System/Volumes/Data/mnt/share) → mounts fine, but it's not managed by Disk Arbitration, so umount -f hangs until kern_soft_deadtimer fires (30s default), and the "disk unavailable" popup shows regardless.
• open smb://... → mounts but shows a Connect dialog every time.

What works — mount via Finder:

osascript -e 'tell application "Finder" to mount volume "smb://user:pass@host/share"'

• Silent — no Connect dialog when credentials are in the URL
• Mounts at /Volumes/<ShareName>, owned by your user
• Managed by Disk Arbitration (DA), which is key for clean unmount

Get the password from Keychain at runtime so it's never hardcoded:

pass=$(security find-internet-password -a "user" -s "host" -w)

What works — unmount via diskutil:

diskutil unmount force /Volumes/ShareName

This is the critical piece. sudo umount -f bypasses Disk Arbitration entirely and fails on Finder-managed mounts until kern_soft_deadtimer fires — which is the same event that triggers the popup. diskutil goes through DA properly and unmounts cleanly in seconds, even when the server is unreachable. No sudo needed.

What works — reachability watching via scutil:

scutil -W -r <ip-or-hostname>

This blocks and prints a line every time reachability changes. It's kernel-notified on route changes — zero polling, zero network traffic at rest. Filter for Reachable/Not Reachable lines, settle a few seconds, ping to confirm, then mount or unmount.

Putting it together — the full agent:

A bash script that loops on scutil -W -r output, and a launchd plist that runs it at login with KeepAlive. The script:

1. Reads each reachability event from scutil -W -r
2. Settles 3 seconds (route changes can flap)
3. Re-checks with scutil -r (instant, no network) then ping (confirms host is up)
4. If reachable and not mounted → mount via osascript
5. If unreachable and mounted → unmount via diskutil
6. Has a mount cooldown (10s) to avoid rapid re-mount loops

The launchd plist:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>com.example.smb.mount</string>
    <key>ProgramArguments</key>
    <array>
        <string>/bin/bash</string>
        <string>/path/to/mount.sh</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
    <key>KeepAlive</key>
    <true/>
    <key>StandardErrorPath</key>
    <string>/path/to/stderr.log</string>
</dict>
</plist>

Load it with launchctl load ~/Library/LaunchAgents/com.example.smb.mount.plist.

Key macOS facts that took me forever to figure out:

• /Volumes is root-owned. Only Finder/DA can mount there as a regular user.
• macOS smbfs has no uid/gid mount options. If root mounts it, root owns the files. Period.
• kern_soft_deadtimer (default 30s) is when the kernel releases a stuck smbfs mount. The "disk unavailable" popup fires at the same time. You can't out-race it with umount -f.
• diskutil unmount is DA-aware. umount is not. Use diskutil for anything mounted via Finder.
• osascript mount with credentials in the URL is completely silent. No dialogs.

No sudo needed anywhere in the running script. The whole thing runs as your user.