Mount shares on OS X on Login and Wakeup

I bought a macbook air recently. This is my first mac, but I am very familiar with Unix/Linux. This is part of a series of posts on using OS X (Mountain Lion).

Last time, I wanted to use automount to mount a Samba share at a fixed location. It didn’t work as I expected.

This time around, I am going to go the simple route and use launchd to mount the share whenever I login.

launchd – System wide and per-user daemon/agent manager

In other words, you can use launchd to launch things. :) It’s great!

Launch a script at login

According to man launchd, user specific launching instructions are stored in ~/Library/LaunchAgents. It’s pretty easy to figure out the syntax just by looking at the examples that’s already there. But for the comprehensive explanation on the plist format for launchd, look at man launchd.plist.

I ended up with this:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>Label</key>
	<string>com.yellowaxe.berunda-mounts</string>
	<key>ProgramArguments</key>
	<array>
		<string>/Users/kal/usr/bin/berunda-mount-shares</string>
	</array>
	<key>RunAtLoad</key>
	<true/>
</dict>
</plist>

It’s important to put in the full path to your script instead of ~kal/usr/bin/berunda-mount-shares.

You can then load this .plist file using launchctl load ~/Library/LaunchAgents/<plist-file-name>

berunda-mount-shares

#!/bin/sh

for i in `seq 1 9`; do
  # wait until interface is active again.
  # is there a better way to do this?
  ifconfig en0 | grep -q 'status: active' && break;
  sleep 5
done

ping -q -c1 berunda >/dev/null || exit; # server not up

pw=$(security find-internet-password -w -a kal -s berunda)

mount | grep -q /opt/kyle/berunda/media && exit; # already mounted
mount -t smbfs smb://kal:$pw@berunda/media /opt/kyle/berunda/media

The for loop is put in to wait for the network interface to become active. This seems to be needed more for the wakeup step. I added some additional changes for server’s status and if the mount is already there.

security find-internet-password is a great way to find your password in the OS X keychain. You do have to store the password in the keychain first… The easiest way is to mount the share in Finder and have it remember your password.

Note that the mount command WILL expose your password on the command line (briefly) since it passes the password to mount_smbfs

Launching a script when the laptop wakes up

For completeness, I wanted to unmount a share when the computer sleeps and remount it when the computer wakes back up. For this, I turn to: SleepWatcher. However, I am not going to install it from the site…

Thanks to a friend, I was turned onto Homebrew. It’s a simple brew install sleepwatcher to install this.

Running SleepWatcher involves our old friend launchd again. Here is the .plist file to use.

de.bernhard-baehr.sleepwatcher.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>Label</key>
	<string>de.bernhard-baehr.sleepwatcher</string>
	<key>ProgramArguments</key>
	<array>
		<string>/usr/local/sbin/sleepwatcher</string>
		<string>-V</string>
                <string>-s /Users/kal/usr/bin/on-sleep</string>
                <string>-w /Users/kal/usr/bin/on-wakeup</string>
	</array>
	<key>RunAtLoad</key>
	<true/>
	<key>KeepAlive</key>
	<true/>
</dict>
</plist>

on-wakeup just simply calls ~kal/usr/bin/berunda-mount-shares and on-sleep calls ~kal/usr/bin/berunda-umount-shares.

And to finish this out.

berunda-umount-shares

#!/bin/sh

ping -q -c1 berunda >/dev/null || exit; # server not up

mount | grep -q /opt/kyle/berunda/media || exit; # already unmounted
umount /opt/kyle/berunda/media

So far, this has been working great.