Error message

If you see something like the following error message when you run a sed command:

invalid reference \1 on `s' command's RHS

then it (probably) means that your regex capture group has not been escaped properly.

So, if you are using a command like:

sed "s/foo(bar)[123]/baz\1/"

then it needs to be escaped like so:

sed "s/foo\(bar\)[123]/baz\1/"

In other words, round parentheses/brackets need to be escaped while the square brackets do not :|

Hope this helps :)

I had the misfortune of trying to install Microsoft's "Virtual CD-ROM Control Panel" which creates, well, a virtual CD/DVD-ROM drive that allows you to mount ISO images. There are a number of other programs that do this, but seeing as to how this was a M$ product, free, Window-7 compatible, and light of weight, I decided to give it a whirl. The README.txt that accompanies the installation file provides instructions for the manual addition of the vcdrom.sys driver to the Windows directory.

I was fiddling around with Unity3D (and C#) and I ran into the following error messages:

InvalidOperationException: Collection was modified; enumeration operation may not execute.
System.Collections.Generic.List`1+Enumerator[UnityEngine.UI.Toggle].VerifyState () (at /Users/builduser/buildslave/mono-runtime-and-classlibs/build/mcs/class/corlib/System.Collections.Generic/List.cs:778)

and

Here I was simply creating a MySQL (5.5) table when suddenly up pops the following error:

#1071 - Specified key was too long; max key length is 767 bytes

After a little trial and error, I found that since one of my VARCHAR fields was being used for a UNIQUE index, MySQL was basically telling me that it was using too much space. When I reduced the length of this field from its initial 512 setting to 256 & then 255, it still complained. However, reducing it further to 128 fixed the issue!

While using Google Chrome on Kubuntu 14.10, the display hung for about 5 seconds before unfreezing with the following notification:

Desktop effects were restarted due to a graphics reset

Once this began occurring with an increasing frequency, I began to do a little digging. Looking through /var/log/kern.log brought the following up:

After installing the shiny new version of Eclipse entitled 'Luna' on a Kubuntu 14.10 box, I found that it crashed/hung when trying to import/clone a Git repository. Starting the application from the command-line triggered the following notice before the crash:

java: /build/buildd/gtk2-engines-oxygen-1.4.5/src/animations/oxygencomboboxdata.cpp:87: void Oxygen::ComboBoxData::setButton(GtkWidget*): Assertion `!_button._widget' failed.

I ran into the following error while running a script that was performing backups of files via rsync over ssh.

error: ssh: connect to host foo.example.com port 22: Connection refused rsync: connection unexpectedly closed (0 bytes received so far) [sender] rsync error: unexplained error (code 255) at io.c(601) [sender=3.0.7]

I ran into the following spiel when I attempted to SSH to a host just now:

On a new Ubuntu 14.04 (Trusty) LTS server, I ran into the following:

$ su -c /bin/bash foo
bash: cannot set terminal process group (3987): Inappropriate ioctl for device
bash: no job control in this shell

However, the su procedure worked and I was logged in as user foo.

After upgrading a Debian install to use PHP 5.4, I ran into the following error:

PHP Warning: Unknown: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected the timezone 'UTC' for now, but please set date.timezone to select your timezone. in Unknown on line 0