Archive for Scripting

Shell swapping in Windows

April 28, 2010 No comments

Until the advent of PowerShell, Windows had been the poor relation when it came to working from the command line when compared with UNIX, Linux and so on. A recent bit of fiddling had me trying to run FTP from the legacy command prompt when I ran into problems with UNC address resolution (it’s unsupported by the old technology) and mapping of network drives. It turned out that my error 85 was being caused by an unavailable drive letter that the net use command didn’t reveal as being in use. Reassuringly, this wasn’t a Vista issue that I couldn’t circumvent.

During this spot of debugging, I tried running batch files in PowerShell and discovered that you cannot run them there like you would from the old command prompt. In fact, you need a line like the following:

cmd /c script.bat

In other words, you have to call cmd.exe like perl.exe, wscript.exe and cscript.exe for batch files to execute. If I had time, I might have got to exploring the use ps1 files for setting up PowerShell commandlets but that is something that needs to wait until another time. What I discovered though is that UNC addressing can be used with PowerShell without the need for drive letter mappings, not a bad development at all. While on the subject of discoveries, I discovered that the following command opens up a command prompt shell from PowerShell without any need to resort to the Start Menu:

cmd /k

Entering the exit command returns you to the PowerShell command line again and entering cmd /? reveals the available options for the command so you need never be constrained by your own knowledge or its limitations.

Scripting, Software, Windows

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Securing MySQL in Fedora

December 4, 2009 One comment

Ubuntu users must be spoilt because any MySQL installation asks you for a root password, a very good thing in my opinion. With Fedora, it just pops the thing on there with you needing to set up a service and setting the root password yourself; if I remember correctly, I think that openSUSE does the same thing. For the service management, I needed to grab system-config-services from the repositories because my Live CD installation left off a lot of stuff, OpenOffice and GIMP even. The following command line recipe addressed the service manager omission:

su – # Change to root, entering password when asked
yum -y install system-config-services # Installs the thing without a yes/no prompt
exit # Return to normal user shell

Thereafter, the Services item from the menus at System > Administration was pressed into service and the MySQL service enabled and started. The next step was to lock down root so the following sequence was used:

mysql # Enter MySQL prompt; no need for user or password because it still is unsecured!
UPDATE mysql.user SET Password=PASSWORD(‘MyNewPass’) WHERE User=’root’;
FLUSH PRIVILEGES;
quit # Exit the mysql prompt, leaving the bare mysql command unusable

For those occasions when password problems keep you of the MySQL shell, you’ll find password resetting advice on the MySQL website but I didn’t need to go the whole hog here. MySQL Administrator might be another option for this type of thing. That thought never struck me while I was using it to set up less privileged users and allowing them access to the system. For a while, I was well stymied in my attempts to access the MySQL using any of those extra accounts until I got the idea of associating them with a host, another thing that is not needed in Ubuntu if my experience is any guide. All in all, Fedora may make you work a little extra to get things like thing done but I am not complaining if it makes you understand a little more about what is going on in the background, something that is never a disadvantage.

Databases, Linux, Scripting, Software, Web, Web Development, Web Technologies

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When buttons stop working…

November 16, 2009 2 comments

One of the things that stopped working as it should after my recent Ubuntu 9.10 upgrade was the Eclipse PDT installation that I had in place. Editing files went a bit haywire and creating projects had me pushing buttons with nothing happening. Whether this was a Java or GNOME issue, I don’t know but I found it happening too on openSUSE 11.2 (there should be more on that distro in a later entry). That was enough to get me looking again at Netbeans.

In both openSUSE (NB version 6.5) and Ubuntu (NB version 6.7.1), I plucked the default offering of Netbeans from the respective software repositories and added the PHP plugin in both cases. Unlike when I last gave the platform a go, things seemed to go smoothly and it looks to have replaced Eclipse for PHP development duties. Project scanning make take a little while but it’s far from annoying and my earlier dalliance with using Netbeans as a PHP editor was stymied by performance that was so sluggish as to make the thing a pain to use. Up to now, Netbeans’ footprints when it comes to its use of PC power never was light so I am wondering if dual-core and quad-core CPU’s help along with a copious supply of RAM. Only time will tell if these inital positive impressions stay the course and I’ll be keeping an open mind for now.

Linux, Scripting, Software, Web, Web Development

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Using the Windows Command Line for Security Administration

July 24, 2009 No comments

While there are point and click tools for the job, being able to set up new user groups, attaching them to folders and assign uses to them using the command line has major advantages when there are a number to be set up and logs of execution can be retained too. In light of this, it seems a shame that terse documentation along with its being hard to rack down answers to any questions using Google, or whatever happens to be your search engine of choice, makes it less easy to discern what commands need to be run. This is where a book would help but the whole experience is in direct contrast to the community of information providers that is the Linux user community, with Ubuntu being a particular shining example. Saying that, the Windows help system is not so bad once you can track down what you need. For instance, knowing that you need commands like CACLS and NET LOCALGROUP, the ones that have been doing the back work for me, it offers useful information quickly enough. To illustrate the usefulness of the aforementioned commands, here are a few scenarios.

Creating a new group:

net localgroup [name of new group] /comment:”[more verbose description of new group]“ /add

Add a group to a folder:

cacls [folder address] /t /e /p [name of group]

The /t switch gets cacls to apply changes to the ACL for the specified folder and all its subfolders, recursive action in other words, while the /e specifies ACL editing rather than its replacement and /p induces replacement of permissions for a given user or group. Using :n, :f, :c or :r directly after the name of a specified user or group assigns no, full, change (write) or read access, respectively. Replacing /p with /r revokes access and leaving off the :n/:f/:c/:r will remove the group or user from the folder.

Add a user to a group:

net localgroup [name of group] [user name (with domain name if on a network)] /add

In addition to NET LOCALGROUP, there is also NET GROUP for wider network operations, something that I don’t have cause to do. Casting the thinking net even wider, I suspect that VB scripting and its ability to tweak the Windows Management Interface might offer more functionality than what is above (PowerShell also comes to mind while we are on the subject) but I am sharing what has been helping me and it can be hard to find if you don’t know where to look.

Scripting, Security, Software, Windows

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Out of memory at line: 56

May 28, 2009 No comments

This is an error that I have started to see a lot in the last few weeks. First, it was with Piwik and latterly with WordPress.com Stats. For the record, I have never seen it on up to date systems but always with IE6 and at page unloading time. The CPU usage hits 100% before the error is produced and that has had me blaming JavaScript in error; it isn’t the cause of all ills. In fact, the cause seems to be a bug in a certain release of Adobe Flash 9 but I am of the opinion that the inclusion of certain features in a Flash movie are needed to trigger it too. I don’t have the exact details of this but WordPress.com Stats worked without fault until a recent update and that is what is making me reach the conclusion that I have. That observation is making me wonder whether we are coming to a point where Flash compatibility is something that needs to factored into the use of the said technology in a website or web application. Updating Flash will solve the problem on the client but it might be better if it wasn’t triggered on the server side either.

Scripting, Software, Video, Web, Web Development, Web Technologies, Web Tools

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About Perl’s Binding Operator

May 20, 2009 No comments

This piece is as much an aide de memoire for myself as anything else but putting it here seems worthwhile if it answers questions for others. The binding operators, =~ or !~, come in handy when you are framing conditional statements in Perl using Regular Expressions, for example, testing whether x =~ /\d+/ or not. The =~ variant is also used for changing strings using the s/[pattern1]/[pattern2]/ regexp construct (the “s” stands for “substitute”). What has brought this to mind is that I wanted to ensure that something was done for strings that did not contain a certain pattern and that’s where the !~ binding operator came in useful; ^~ might have come to mind for some reason but it wasn’t what I needed.

Scripting

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