Jeff Kelley’s Blog » launchd http://blog.slaunchaman.com Mac tips, iPhone applications, and the like Fri, 02 Dec 2011 04:51:07 +0000 en hourly 1 http://wordpress.org/?v=3.3.1 How-To: Run a LaunchDaemon That Requires Networking http://blog.slaunchaman.com/2010/07/01/how-to-run-a-launchdaemon-that-requires-networking/ http://blog.slaunchaman.com/2010/07/01/how-to-run-a-launchdaemon-that-requires-networking/#comments Thu, 01 Jul 2010 17:28:37 +0000 Jeff Kelley http://blog.slaunchaman.com/?p=300 I’m a big fan of using launchd to automate things in Mac OS X. That serves me well, as that’s how Apple wants things done moving forward. That said, one of launchd’s biggest shortcomings is a lack of a dependency system. There is currently no way, for instance, to specify in a LaunchDaemon’s property list that the daemon requires the network to be active in order to run. This is problematic for some things, such as a script I wrote to automatically set the computer’s hostname based on the DNS server (more on that later). Luckily, Apple has already defined a function, CheckForNetwork, in /private/etc/rc.common. Here it is in all its glory:

##
# Determine if the network is up by looking for any non-loopback
# internet network interfaces.
##
CheckForNetwork()
{
	local test

	if [ -z "${NETWORKUP:=}" ]; then
		test=$(ifconfig -a inet 2>/dev/null | sed -n -e '/127.0.0.1/d' -e '/0.0.0.0/d' -e '/inet/p' | wc -l)
		if [ "${test}" -gt 0 ]; then
			NETWORKUP="-YES-"
		else
			NETWORKUP="-NO-"
		fi
	fi
}

In your code, simply include rc.common, then call CheckForNetwork as needed. An example:

#!/bin/bash

# Example Daemon Starter
. /etc/rc.common

CheckForNetwork

while [ "${NETWORKUP}" != "-YES-" ]
do
        sleep 5
        NETWORKUP=
        CheckForNetwork
done

# Now do what you need to do.

Note that this will keep the script running indefinitely until CheckForNetwork sets NETWORKUP to “-YES-,” so if there’s a networking problem your code may never execute.

]]> http://blog.slaunchaman.com/2010/07/01/how-to-run-a-launchdaemon-that-requires-networking/feed/ 2 Automatically get the latest Chromium snapshot with launchd http://blog.slaunchaman.com/2009/05/19/automatically-get-the-latest-chromium-snapshot-with-launchd/ http://blog.slaunchaman.com/2009/05/19/automatically-get-the-latest-chromium-snapshot-with-launchd/#comments Wed, 20 May 2009 04:24:08 +0000 Jeff Kelley http://blog.slaunchaman.com/?p=183 I’ve been checking out the snapshots of Chromium recently, and they’re coming quicker than you can say “multithreaded web browser.” To facilitate always having the latest version, I wrote a quick LaunchAgent that takes care of it on Mac OS X. First, I have a script named ~/bin/chromiupdate:

#!/bin/bash

# Downloads the latest version of Chromium.

remove_working_dir()
{
    rm -rf "${WORKING_DIR}"
    exit 0
}

USER_DIR=$(dscl . -read /Users/$(whoami) NFSHomeDirectory | awk '{ print $2 }')
USER_APP_DIR="${USER_DIR}/Applications"
CHROMIUM_DIR="${USER_APP_DIR}/Chromium.app"
LATEST_URL="http://build.chromium.org/buildbot/snapshots/sub-rel-mac/LATEST"
TMP_DIR="/private/tmp"
WORKING_DIR="${TMP_DIR}/.chromium_launchd"
URL_BEGIN="http://build.chromium.org/buildbot/snapshots/sub-rel-mac"

if [ ! -d "${CHROMIUM_DIR}" ]; then
    mkdir -p "${CHROMIUM_DIR}"
fi

INSTALLED_VERSION="$(defaults read "${CHROMIUM_DIR}/Contents/Info" SVNRevision)"
VERSION=$(curl "${LATEST_URL}")

if [ "${VERSION}" != "${INSTALLED_VERSION}" ]; then
    logger Installed Chromium version \(${INSTALLED_VERSION}\) does not equal \
            latest version \(${VERSION}\), updating now...
    mkdir "${WORKING_DIR}" || exit 1
    trap remove_working_dir 1 2 3 6 15
    cd "${WORKING_DIR}" || exit 1
    curl -O "${URL_BEGIN}/${VERSION}/chrome-mac.zip"
    unzip chrome-mac.zip
    rsync -HavP --exclude="Contents/MacOS/chrome_debug.log" \
          "${WORKING_DIR}/chrome-mac/Chromium.app/" "${CHROMIUM_DIR}/"

    if [ "$(ps -aef | grep -i chromium | grep -v grep)" != "" ]; then
        open "${USER_DIR}/Library/Scripts/Chromium Update Dialog.app"
    fi

    logger "Chromium update complete. Version ${VERSION} installed."

    remove_working_dir
else
    logger Installed Chromium version \(${INSTALLED_VERSION}\) is up-to-date. \
           No action needed.
fi

exit 0


Next, I have a property list named ~/Library/LaunchAgents/com.slaunchaman.chromium.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>com.slaunchaman.chromium</string>
        <key>Program</key>
        <string>/Users/slauncha/bin/chromiupdate</string>
        <key>KeepAlive</key>
        <false/>
        <key>StartInterval</key>
        <integer>3600</integer>
        <key>RunAtLoad</key>
        <true/>
        <key>StandardOutPath</key>
        <string>/dev/null</string>
        <key>StandardErrorPath</key>
        <string>/dev/null</string>
    </dict>
</plist>

Finally, I have an AppleScript at ~/Library/Scripts/Chromium Update Dialog.app:

display dialog "Chromium was just updated. You should restart it."

The LaunchAgent runs once an hour, checking to see if the installed version of Chromium is older than the latest snapshot. If so, it downloads it and uses rsync to copy the changes. The script places Chromium in ~/Applications, but it shouldn’t be hard to modify to put it into /Applications.

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