Properly Daemonize

[erluko]

Switch to using launchd rather than calling daemon(3)

[erluko]

One of the obstacles to launching via launchd was configurable handling of the output and error streams of the launched utility. That feature was added in v1.1.0 via the -o, -e, -O, and -E switches.

v1.1.0 also resolved another obstacle: the inability to reset state and manually invoke the utility. That is now possible by sending SIGHUP.

All that remains to resolving this issue is to build a sample launch agent configuration, and perhaps to no longer daemonize by default.

[rsnow]

EDIT: Thinking this through before I put it into action, I think there may need to be some thought to permissions/ownership/group on the script that is executed.

Couldn't we just borrow a .plist from something like dnsmasq from brew?

<?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>homebrew.mxcl.dnsmasq</string>
    <key>ProgramArguments</key>
    <array>
      <string>/usr/local/opt/dnsmasq/sbin/dnsmasq</string>
      <string>--keep-in-foreground</string>
      <string>-C</string>
      <string>/usr/local/etc/dnsmasq.conf</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
    <key>KeepAlive</key>
    <true/>
  </dict>
</plist>

and change it to

<?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>netwatcher.erluko</string>
    <key>ProgramArguments</key>
    <array>
      <string>/usr/local/bin/netwatcher</string>
      <string>-d</string>
      <string>-f</string>
      <string>/Users/somedude/bin/script.sh</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
    <key>KeepAlive</key>
    <true/>
  </dict>
</plist>

Then put that in /Library/LaunchDaemons and do the whole

sudo launchctl load -w /Library/LaunchDaemons/netwatcher.erluko.plist