launchd run command every minute of a specific hour

Edit start

You got it all correct except for enclosing your <dict> element inside an <array> element. Your script will run every minute from 21:00 to 21:59 with the following as your StartCalendarInterval key :

    <key>StartCalendarInterval</key>
    <array>
        <dict>
            <key>Hour</key>
            <integer>21</integer>
        </dict>
    </array>

If you wanted your script to run every minute, every hour, every day, every year, the following would be the correct (but certainly not obvious) syntax for that:

    <key>StartCalendarInterval</key>
    <array>
        <dict/>
    </array>

My original answer (below) would also work, but it's clearly much more tedious! OTOH, if one needed every other minute, or certain minutes, it might be useful.

Edit end

<key>StartCalendarInterval</key>
    <array>
        <dict>
            <key>Minute</key>
            <integer>0</integer>
        </dict>
        <dict>
            <key>Minute</key>
            <integer>1</integer>
        </dict>
        <dict>
            <key>Minute</key>
            <integer>2</integer>
        </dict>
        <dict>
            <key>Minute</key>
            <integer>3</integer>
        </dict>
        <dict>
            <key>Minute</key>
            <integer>4</integer>
        </dict>

       ... ad nauseum ...

        <dict>
            <key>Minute</key>
            <integer>59</integer>
        </dict>

    </array>

To answer your question, "Why is this not running every minute?", it's only because you failed to enclose <dict> inside <array>. FWIW, it seems very odd to me also, and WHY it's designed this way is an answer I'd like to hear myself. But then I guess Apple could use the defense that "just because the semantics are similar does not mean the syntax is."

I think this is a bug in launchd.

If I take out the hour designation, it fires every minute.

But if I restrict the plist to only 9pm, then it only fires once.

Update

This is what I tried (with the hour changed to ’12’ because that’s the current hour when I tried to test it).

The ’test.txt’ file never gets created.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>com.tjluoma.everyminute</string>
    <key>Program</key>
    <string>/bin/date</string>
    <key>StandardOutPath</key>
    <string>/Users/tjluoma/Desktop/test.txt</string>
    <key>StartCalendarInterval</key>
    <array>
        <dict>
            <key>Hour</key>
            <integer>12</integer>
        </dict>
    </array>
</dict>
</plist>

This does create/update the file every minute

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>com.tjluoma.everyminute</string>
    <key>Program</key>
    <string>/bin/date</string>
    <key>StandardOutPath</key>
    <string>/Users/tjluoma/Desktop/test.txt</string>
    <key>StartCalendarInterval</key>
    <array>
        <dict/>
    </array>
</dict>
</plist>