Monday, May 23, 2016

Disable Hibernate in Windows

Hibernate is a neat feature that is especially useful on laptops. Hibernate is different than sleep/standby in that with sleep/standby, the system shuts down most of the hardware, including the hard drive, but keeps the RAM powered to save the current state. This will (very) slowly drain the battery, but is extremely fast to resume. Hibernate saves the RAM state to hard disk and powers everything off. This is slower to resume than sleep/standby, but won't drain the battery and is still faster to resume than a full shutdown.

By default on Windows systems, hibernate is enabled. This includes servers, which should probably never enter hibernate state. The problem with hibernate, especially on older servers, is that the system reserves hard disk space large enough to store the contents of the RAM in the C:\hiberfil.sys file, which is a protected system file. If you have a small hard drive and a bunch of RAM, this can very quickly eat up a lot of valuable disk space. The only way to get this space back is to disable hibernate, which in most cases for servers, is a best practice anyway.

The easiest way to disable hibernate is to open a command prompt (cmd.exe) as administrator and run this command:
powercfg.exe -H off

Monday, May 16, 2016

Install ifconfig in RHEL or CentOS

Depending on the OS version and which configuration you selected during installation, you might discover that ifconfig is not installed by default in your new RHEL or CentOS build. Unfortunately, searching yum might not tell you the name of the package you need to install. I'll save you some looking, the package you need is called "net-tools."

You can install net-tools with this command:
# yum -y install net-tools

Monday, May 9, 2016

List All Domain Controllers for a Given Domain Using PowerShell

PowerShell is an awesome way to gather a bunch of useful information about the system you're on or the domains you're connected to.

This useful command will list all of the Domain Controllers for the given domain. Make sure to replace <domain> with your domain.
> Get-ADDomainController -Filter * -server <domain> | Select-Object name, domain

Monday, May 2, 2016

Use PowerShell To Delete Files Older Than

So you have a machine with a bunch of old files that are just taking up space and you want to quickly and easily clear them all out? PowerShell to the rescue. This command will delete all files in the current directory that were created more than 30 days ago. You can change the number of days based on your needs.
> Get-ChildItem | Where-Object{$_.CreationTime –lt (Get-Date).AddDays(-30)} | Remove-Item

Want to clear out the current directory AND all subdirectories? Add the -Recurse flag after Get-ChildItem.
> Get-ChildItem -Recurse | Where-Object{$_.CreationTime –lt (Get-Date).AddDays(-30)} | Remove-Item

Want to suppress any "are you sure" prompts? Add the -Recurse flag after Remove-Item.
> Get-ChildItem -Recurse | Where-Object{$_.CreationTime –lt (Get-Date).AddDays(-30)} | Remove-Item -Recurse