Apple

A few of my tech projects experience occasional hiccups and need to be soft-reset from my Linux host (e.g. Wi-Fi SSID routed through VPN, Windows gaming VM with hardware passthough). This was annoying as it meant having a machine nearby to SSH and execute a few simple commands -- often just a systemctl restart foo. Fortunately, homebridge-cmdswitch2 can easily expose arbitrary commands as lights so I would be able to easily bounce the services via my phone.

First, since Homebridge should be running as its own system user, we need to give it permissions to restart services (as root). We don't want to grant services to all of /bin/systemctl, so a wrapper script will be placed at /usr/local/bin/serviceswitch to encapsulate the desired behavior. Grant the homebridge user permission to run it with sudo:

cat << EOF > /etc/sudoers.d/homebridge-cmdswitch
homebridge ALL = (root) NOPASSWD: /usr/local/bin/serviceswitch

Next, let's create that /usr/local/bin/serviceswitch script with service status, start and stop commands - using such a wrapper also has the benefit that complex checks consisting of several commands can be performed. Keep in mind these are now being run as root from Homebridge!

#!/bin/sh

if [ "$(id -u)" -ne 0 ];then
  echo "You must run this script as root."
  exit 1
fi

usage() {
  error="$1"
  if [ ! -z "$error" ];then
    echo "Error: $error"
  fi
  echo "Usage: $0 [action] [service]"
}

action="$1"
service="$2"
if [ -z "$action" ] || [ -z "$service" ];then
  usage
  exit 1
fi

case $action in
  start|stop|status) ;;
  *) usage "invalid action, must be one of [start, stop, status]"; exit 1;;
esac

case $service in
  vm-guests)
    [ "$action" == "start" ] && (systemctl start libvirt-guests)
    [ "$action" == "stop" ] && (systemctl stop libvirt-guests)
    [ "$action" == "status" ] && { systemctl -q is-active libvirt-guests; exit $?; }
    ;;
  fileserver)
    [ "$action" == "start" ] && (systemctl start smb;systemctl start nmb;systemctl start netatalk)
    [ "$action" == "stop" ] && (systemctl stop smb;systemctl stop nmb;systemctl stop netatalk)
    [ "$action" == "status" ] && { (systemctl -q is-active smb && systemctl -q is-active nmb && systemctl -q is-active netatalk); exit $?; }
    ;;
  web)
    [ "$action" == "start" ] && (systemctl start httpd)
    [ "$action" == "stop" ] && (systemctl stop httpd)
    [ "$action" == "status" ] && { systemctl -q is-active httpd; exit $?; }
    ;;
  *) usage "invalid service"; exit 1;;
esac
exit 0

Finally, here is the relevant platform section from the homebridge config:

{
  "platforms": [{
    "platform": "cmdSwitch2",
    "name": "Command Switch",
    "switches": [{
       "name" : "vm-guests",
        "on_cmd": "sudo /usr/local/bin/serviceswitch start vm-guests",
        "off_cmd": "sudo /usr/local/bin/serviceswitch stop vm-guests",
        "state_cmd": "sudo /usr/local/bin/serviceswitch status vm-guests",
        "polling": false,
        "interval": 5,
        "timeout": 10000
    },
    {
       "name" : "fileserver",
        "on_cmd": "sudo /usr/local/bin/serviceswitch start fileserver",
        "off_cmd": "sudo /usr/local/bin/serviceswitch stop fileserver",
        "state_cmd": "sudo /usr/local/bin/serviceswitch status fileserver",
        "polling": false,
        "interval": 5,
        "timeout": 10000
    },
    {
       "name" : "web",
        "on_cmd": "sudo /usr/local/bin/serviceswitch start web",
        "off_cmd": "sudo /usr/local/bin/serviceswitch stop web",
        "state_cmd": "sudo /usr/local/bin/serviceswitch status web",
        "polling": false,
        "interval": 5,
        "timeout": 10000
    }]
  }]
}

I have been testing the Drupal support module locally which features the ability to create tickets from email messages to an IMAP inbox. It requires the imap_open() PHP function provided by the imap PHP extension, which unfortunately is not included in the OS X builds of PHP.

ivucica has published a wonderful script to his blog that compiles the IMAP extension without having to recompile PHP entirely, but unfortunately it was not working for me and nobody else seemed to have my problem either. Compiling the imap library and PCRE went very smoothly, but when it came time to build the PHP extension this error appeared during ./configure:

Well, crap. I check config.log and determine it's a linking failure:

I couldn't figure out why it wasn't picking up the symbols from libssl, even when manually trying to compile said file and adding a -lssl flag.

After an hour of struggling with it and my debugging efforts going nowhere, I try adding -lcrypto for the hell of it and it works!

tl;dr, if you get this error then simply replace the following line of the aformentioned script:

With the following line that adds the required linker flags:

That's it!

With Apple's changes surrounding iCloud, managing media on iOS devices has become much easier and it is no longer absolutely bound to a single computer. However, I have still found it tricky to sync a single iOS device with multiple computers (different iTunes libraries) without having to entirely wipe the device first.

I synchronize my iTunes library between two computers regularly, so both machines have up-to-date copy of all media files. Furthermore, I set them up with the same username (but different hostname), so the iTunes media file paths are identical between machines.

Searching Apple forums revealed this solution by turingtest2: apparently, each iTunes library is assigned a randomly-generated "library ID". This identifier is stored on the iOS device, so if it doens't match when connecting to a new computer, it will request to wipe the device before proceeding with the sync. Simply copying my entire ~/Music folder from one machine to the other was enough copy all the iTunes metadata (including the library ID) and my device now happily synchronizes on either machine. For those wanting to save time and not copy their entire ~/Music folder, see the forum post for the exact files you'll need to copy.

In previous version of OS X, the iSync application could be used to reset sync history. This technique often resolved a bunch of miscellaneous bugs and sync-related problems. The iSync application has since been removed in OS X Lion and Apple's support documents aren't of much help. This one claims that resetting sync services can be performed from iSync in Leopard and from the Sync menu extra in later version of OS X. This document describes how to enable the menu extra in the MobileMe settings. Besides the fact that MobileMe is deprecate and no longer in use, the option described in that document to enable the Sync menu extra only appears after signing in to MobileMe... Which is deprecated.

Fortunately, there's a hidden folder you can open to enable any menu extra manually! Open Finder and select Go > Go to Folder (or press Command+Shift+G). In the prompt that appears, type: /System/Library/CoreServices/Menu Extras/. This should bring you to a folder with a bunch of menu extras that you can double-click to add to the menu bar. The one of interest in this case is Sync.menu, which should appear in your menu bar a second or two after opening it.

Once it's in your menu bar, hold Alt/Option and click on it to expose the advanced options and click "Reset Sync Services". After that's done, you can remove it from your menu bar if you'd like by holding Command and then clicking & dragging it out from the menu bar.

Lion introduced a new Time Machine feature the OS would automatically create local snapshots of files so that even without a backup disk attached, you could still enter time machine and recover or undo changes to certain files. As your disk space becomes low, this space is automatically freed and the rate of snapshot creation is reduced.

This is great on desktops and I would assume the newer Macbook Pros that have better disks, but on my older MacBook Pro I've noticed that Safari has had trouble loading web pages and during this time, I hear the disk thrashing for about a minute or so and then all of a sudden the page loads. After a bit of researching and some help from the 'fs_usage' command, I discovered that a process called 'mtmd' was accessing the filesystem often and it turns out that mtmd is responsible for creating these local time machine snapshots. A quick Google revealed how to disable the local snapshot functionality:

We'll see if that helps the disk thrashing! I did immediately recover 1GB of disk space though which is a good sign.