Snow Leopard and crontab

It seems that somewhere along the line the ability to list and edit your user crontab went away, maybe they are wanting to migrate people across to "launchd" and "launchctl" as the preferred way of doing things. One of the things I still like about Apple is the fact that under the hood it's still rock solid Unix, and that most of the time, if it works on Ubuntu it works on OS X too, sometimes it may look a little different but in the end you can still bask in some command line warmness to be able to achieve what you want.

So, if the commands crontab -l and crontab -e appear not to work anymore, how do you get the same result? For the record, running uname -a on my iMac gives me:

Darwin Macintosh.local 10.8.0 Darwin Kernel Version 10.8.0: Tue Jun 7 16:33:36 PDT 2011; root:xnu-1504.15.3~1/RELEASE_I386 i386

Your mileage may vary if its radically different than that... a long time back I wrote a PHP class wrapper around the cron system so that it would allow an application to programmatically add, edit and delete cron jobs without upsetting what was already in place. How did I do this from PHP? Simple. There is another way to use the crontab command that a lot of people know but not a lot of people know people who know how to do it, so here it is...

Dumping your current crontab:

crontab -l ~/tmp/mycrontab

Once there, you can edit it to your hearts content until it's how you want it and then

Updating your current crontab:

crontab ~/tmp/mycrontab

All my PHP code did was wrap that in calls to exec() and all my stuff I put at the bottom of the file between two "special" markers do I'd know where was safe to read and write, a reminder of my days with Microsoft Frustration Classes waaaaaayyyyyy back in the 80's when VC++/MFC was "hot". LMFAO

So, there you are. Voila. Job done. All over. Simple once you know how. Hope that helps somebody else save a bit of head-scratching.

Comments

The Coolest Shortest PHP Function I Will Ever Write

Having now released my own programming language, FELT , and learned a lot about this and that in the process I have of late, in the evenings, been struggling to reconcile my love of LISP and how simple FELT makes some PHP coding task leaner and meaner with the fact that I still have to use PHP for my day job. In my language, FELT , I have used the square brackets to define a "normal" array and curly braces to define a "key-value" array, mainly because this is identical to JSON format and anybody familiar with Javascript coding just won't have any issues getting to grips with that now will they! Let's take some simple examples of FELT code: (defvar simple-array [1 2 3 4]) (defvar simple-map {:name "Eric" :age 42 :occupation "Viking Hacker"}) When FELT has done its thing, we get the following PHP code, $simple_array = array(1, 2, 3, 4); $simple_map = array('name' => "Eric", 'age' => 42, ...

Handling multipart/form-data with NanoHTTPD

I am in the process of reviving an old project from 2014 that I never finished because of other work commitments. In that time, bitrot has set in, the Android API has moved on and all in all, the home-brewed HTTP server I wrote using SocketServer and the org.apache libraries had to go! I looked around, found a couple of contenders and after much time decided to go with NanoHTTPD because it is lean, small and fits in exactly two files. The main server is in one file `NanoHTTPD.java`and there is another file called `ServerRunner.java` which manages instances of running servers. The others The other project I looked at is this one: https://github.com/koush/AndroidAsync which led me a merry dance and I just couldn't figure out how get the POST data I had uploaded. I spent a few days really digging at it with Wire Shark too to make sure the data was going up. It was. Whatever... I had used it via a gradle dependency entry but I dropped it and went back to NanoHTTPD. For m...

Using a RAM disk with Opera on OS X

Having recently configured AndroidStudio to use a RAM disk for Gradle, I thought I would look around and see if I can use the remaining space for Opera. This is essentially a reproduction of this fine page: http://www.ghacks.net/2010/10/20/how-to-change-the-opera-cache-directory/ That page does not deal with Macs though and after a little bit of experimentation I came up with this spell: open /Applications/Opera.app/ --args --disk-cache-dir=/Volumes/RamDisk/opera For the record, here is my Opera version: Make sure that the specified folder exists before starting Opera, if might automatically create the folder for you but I didn't bother to find out, I hate disappointment. And for the record, the way I create a RAM disk on my iMac, which is done automatically when I log in, is like this: diskutil erasevolume HFS+ "RamDisk" `hdiutil attach -nomount ram://4194304` The above line was courtesy of this YouTube video: Thanks to Bartech TV then! So, with Turbo m...

The Adventures of Emacs the Viking

Search This Blog