Create a persistent runtime log file *with duplicates*

com.initvoid.log.runtime.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "https://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist>
    <dict>
        <key>Label</key>
        <string>com.initvoid.log.runtime</string>
        <key>ProgramArguments</key>
        <array>
            <string>/usr/bin/grep</string>
            <string>--no-filename</string>
            <string>--fixed-strings</string>
            <string>--regexp=SHUTDOWN_TIME</string>
            <string>--regexp=BOOT_TIME</string>
        </array>
        <key>RunAtLoad</key>
        <true/>
        <key>StandardInPath</key>
        <string>/var/log/system.log</string>
        <key>StandardOutPath</key>
        <string>/var/log/runtime.log</string>
        <key>WorkingDirectory</key>
        <string>/tmp</string>
        <key>RootDirectory</key>
        <string>/var/jail</string>
        <key>Nice</key>
        <integer>10</integer>
    </dict>
</plist>