http://140dev.com/twitter-api-programming-tutorials/hello-twitter-oauth-php

but for the life of me I couldn’t get it to work; I kept getting a 401 return code saying that my app did not have write access.
But, I had given it write access so…what happened!?

Actually, the cause and effect, and subsequent fix, was simple but not entirely obvious;
I had created the app as a READ ONLY app to start with and generated all the codes for it.
I then had realised my mistake and set the app permissions to Read & Write. The dev.twitter.com page for my subsequently showed me that me that the app now had the required access.
Still, I got a 401 error back.

I had not, however, recreated my access tokens (there’s a button for this at the bottom of the page.)
Once I did this the app worked.

So; the confusingly named “Access Token” and “Access Token Secret” need to be regenerated if you change the permissions for your app. This is not obvious to me since I would expect these tokens to encode the identiy of the app and therefore allow Twitter to access its permissions through the back-end…
But there you go, at least now it works.

• I have a machine with two hard disks; on one there’s a Fedora (15) install and on the other Windows 7
• I’ve got Grub set up to allow me to boot from either

Fedora 14
Netbeans 6.9 + g++ 4.5.1 and MPICH2

Problem

I wanted to play around with OpenMP and C++ and I wanted to use the NetBeans IDE but had no luck compiling and/or linking.

Naively I did this:

• installed MPICH2 packages using the package manager (I tried first with yum but that didn’t work at all…could be a red herring but be warned, see end notes.) 
• openend up NetBeans, created a C++ app project and wrote a little Hello World program with a simple #pragma omp parallel section
• I hit compile and…naturally, it just compiles a standard single-threaded app (ignoring the unrecognized pragma)
• So, I tried to compile the program on the command line using the mpic++ compiler/linker wrapper which is installed with openmpi-devel
  • It failed with the errors about not finding -lmpichcxx, -lpmipch and -lopa (again, see end notes)

Solution

1. mpic++ for some reason or other produces the wrong (???) command line;
   1. it typically looks like this: 
      1. c++ -m32 -O2 -Wl,-z,noexecstack -I/usr/include/mpich2-i386 -L/usr/lib/mpich2/lib -L/usr/lib/mpich2/lib -lmpichcxx -lmpich -lopa -lpthread -lrt
   2. but it should look like this (highlighting changes from above only):
      1. c++ -fopenmp -m32 -O2 -Wl,-z,noexecstack -I/usr/include/mpich2-i386 -L/usr/lib/mpich2/lib -L/usr/lib/mpich2/lib -lmpichcxx -lmpich -lgomp -lpthread -lrt
2. Therefore, in the properties of your NetBeans project, under C++ Compiler::Additional Options you set the command line to
   1.  -fopenmp -m32 -O2 -Wl,-z,noexecstack -I/usr/include/mpich2-i386 -L/usr/lib/mpich2/lib -L/usr/lib/mpich2/lib -lmpichcxx -lmpich -lgomp -lpthread -lrt
   2. Alternatively you can of course use that as-is on the command line
3. ..and compile…and it runs, and according to my perf monitor it uses more than one thread. Perfect.

Notes

libgomp is the GNU OpenMP library and it is part of the gcc 4.5.x install (and possibly earlier, but I haven’t checked/tested this). I don’t know what “libopa” was/is (can’t find anything about it) so it might even be a typo (although this would be horrendous and hopefully not the case) – If anybody reading this can shed some light….?

I tried with c++ and g++ both in the project settings in NetBeans but it doesn’t matter which one you use, as long as the command line is correct as in step 2 above.

The issue alluded to concerning installing OpenMPI using Yum; I did this first #yum install openmpi openmpi-devel but it seems that this, although it installed the libraries, did not create appropriate symlinks to them so that ld could find them (see note about ld failing at the top of this post.) I therefore manually created these and it fixed the linking, but as I subsequently did an install of MPICH2 using the package manager before I got the app running properly I can’t verify exactly if this had a positive effect overall or if it was a red herring. If anybody can recreate this and confirm then that would be great.

Btw, here are some great links for some OpenMP examples and tutorials:

http://www.codeproject.com/KB/library/Parallel_Processing.aspx

http://bisqwit.iki.fi/story/howto/openmp/#ExampleCalculatingTheMandelbrotFractalInParallel

https://computing.llnl.gov/tutorials/openMP/#CFormat

Solution
– Take note of the MAC address first assigned by VBox when the VDI and machine is first created and then, for each new machine using that VDI, go to Settings::Network::Advanced and type the MAC address directly into the MAC field.

UPDATE: If you’ve got a VDI that you move around to multiple machines (as I do) and you create new virtual machines to use it with then you want to make sure that each of these new ones use the correct MAC address also, of course, otherwise you have no network. Just create a new machine using said VDI and fire it up. If it’s a Windows machine then you can use ipconfig /all to get the MAC address, otherwise, for Linux, you can use ifconfig or alternatively you can just look at the MAC address setting for eth0 in the /etc/udev/rules.d/70-persistent-net.rules file (there will be lines in there that look something like this:
# PCI device 0x10b7:0x9200 (3c59x) (custom name provided by external tool)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*",
ATTR{address}=="XX:YY:ZZ:UU:VV:WW", ATTR{type}=="1", NAME="eth0"

and it’s the ATTR{address} field that stores the MAC address.)

Notes
– I ran into this because I share VDIs between different machines. I would bring the VDI (for an Ubuntu install for example) to a different laptop and set up a new machine in VirtualBox, using the VDI which I store on a USB drive. It would run but the network card would fail to initialize and running ifconfig would just show me the lo (loop back) device being active. Trying to ifup eth0 just threw up “device not found” errors. At first I hand edited the rules file but then I realized that the simplest (and perhaps most obvious) solution was to just assign the same MAC address to all the new machines myself.

However, I digress. As I installed more and more apps into my Win7 Virtual Machine I started running out of disk space so here follows a brief explanation of what I did (and do) when I need it (the VDI…) to grow. (Note that I didn’t originally create it using the  ”dynamically expanding storage” option in VBox and if I had I might not be in this predicament but there you go.)

So;

1. Create a new harddrive using the Virtual Media Manager in VBox and make sure it’s the size you want
   1. NOTE: Again I didn’t create the new disk as dynamic, but rather as static…I don’t know if the following steps would work if it was dynamic (somehow I doubt it but if you try then please let me know how it went…)
2. Release and Remove your old harddrive from VBox’ grasp using the Virtual Media Manager;
   1. You have to do this otherwise the next step will fail. All you need to do is to release it, then remove it and REMEMBER to “Keep” the hard disk image when you do that!
3. Clone your old (and smaller) VDI into the new (and larger) one like so using the VBox command line tool:

VBoxManage clonehd --existing OLD.vdi NEW.vdi

4. Now go back into Virtual Media Manager and add the NEW.vdi drive
5. In the settings for your virtual machine (the one that previously used the OLD.vdi) you change it to use NEW.vdi
6. Downloadsystemrescuecd.iso (or any LiveCD with a Linux Distro and GParted on it. The remaining steps assume you can run GParted)
7. Attach the LiveCD to your virtual machine so that it will be booted when it starts
8. Boot your virtual machine…
9. Run GParted;
   1. The virtual machine’s hard disk will be allocated into the “old” partition (which is the smaller size) and an extra, unallocated, partition which is whatever extra space you now have in your new and (larger) hard disk
10. Resize the smaller partition (old) to take up all of the (new) disk
    1. NOTE: this assumes your guest OS uses a file system that GParted understands. In my case this was NTFS (Windows) but if you are attempting this to grow something else, and utterly esoteric, I can’t guarantee it will work. However, it would have to be very esoteric…
11. Shut down the virtual machine
12. Release the ISO (sysrescd.iso in my example)
13. Reboot….
14. Presto, you’re done! The machine should boot up happily and Windows will tell you that the C: drive is whatever size NEW.VDI was created as

Certainly beats using CloneZilla to try and save off the old image and restore it. I tried that too and it didn’t work but even if it did this method seems simpler.

Anyway, I have a fix that works for me and it’s simple; run p4 to edit your client spec (‘foo’ in my example) and remove the line containing ‘Host‘…That line restricts access to a given host and is the one that seems to get “creatively altered” somehow to add a “.local” extension to it. Remove this restriction and all works.

HOWEVER: this fix assumes you don’t need host restriction which you might, of course. I suspect it might not be a problem for you anyway then since you’ll be using something like a properly resolved IP or network name…so there.

And that was it; Wine is now usable.

After much trying and testing I think I’ve finally found a solution that at least seems relatively stable. It involves using rsync directly from a telnet or ssh log-in on the DS to do the backing up.

Here’s what I’ve done:

• Formatted my 2TB drive to the EXT3 linux file format. I tried FAT32 and I tried NTFS but permission problems prevailed. EXT3 seems to work best with the 207+ at least
• logged in to the DS using ssh and…
• ..ran this first just to get the whole directory structure mirrored (this took a LONG time with a couple of restarts, hence the “ignore-existing” flag…)
  • rsync -rv –progress –ignore-existing /source/on/DS/ /dest/on/USB/drive
• ..thereafter, whenever I’ve backed up from my other machines to the DS or anything else has changed, I run this to update the external drive
  • rsync -rvu –progress /source/on/DS/ /dest/on/USB/drive

These things mostly work and are stable (sometimes the drive mysteriously ejects but it seems to do less so than if I try to use the DSM interface)

I’ve tried to rsync using the server’s IP address;

192.168.0.193:/volume1/Jarl/backup

and I’ve tried to use a mount point after adding a cifs mount statement to my fstab file:

//192.168.0.193/Jarl /mnt/ds_jarl cifs credentials=/etc/.ds_credentials,_netdev 0 0


To no avail and still I get problems with rsync throwing up “Permission denied (13)” errors when it tries to create (or delete) directories.

From what I’ve been able to gleam from various fora there seems to be an issue that quite a few people have been struggling with in one form or other. If this is related to a subtle difference in the use of CIFS or Samba I don’t know but the bottom line is that it doesn’t work…for me at least.

Anyway, here be what I did to make this work for me. It might not work for you but hopefully it will give you a possible avenue to try out, should you have problems getting rsync to work with your DS207+.

• Firstly I followed the instructions here to create an ssh key file. I subsequently copied one into my /home/jarl/.ssh folder (had to create it first) as per instructions. I also copied it over to a new /homes/admin/.ssh folder on the DS207+ (simply using the File Station.) Following that I could ssh in without entering a password BUT as opposed to what the instructions on said web site says I had to specify that I was the “admin” user for this to work. I believe this has something to do with the limitations on who can ssh into the DS207+. In short, the ssh line to log in had to be this:
  • ssh -l admin -i /home/jarl/.ssh/rsync-key 192.168.0.193
  • NOTE: the use of “-l admin” here!
• Next I could compose the full rsync command line and instruct it to use ssh (as admin!) to connect to my NAS and do it’s thing:
  • rsync -rv -o -c -z -e ssh -l admin -i /home/jarl/.ssh/rsync-key 192.168.0.193:/volume1/Jarl/Backup /home/jarl/
  • NOTE: I composed the whole command line using grsync and just added the -e ssh… part manually

This works fine now, although all the files sync’d up are owned by “admin” of course…

I will try to make this work for the standard user as well; it makes no sense that you should have to be admin to make this work..!