Awk & sed Snippets for SysAdmins

Uninstall PostgreSQL from Ubuntu

Ok, so this is a very simple one: uninstall PostgreSQL running on Ubuntu. There are a bunch of pieces to the database server and just running “apt-get remove postgresql” will still leave you with with a bunch of leftovers

A Faster Way to Delete Many Folders

This issue is particularly annoying when dealing with expansive directory structures mounted via NFS. Let’s say you have a directory with ten thousand folders and each of them has more subfolders and files. And you …

System Recovery: Useful Tools

The following is a brief collection of open-source and/or free tools I regularly use for various system recovery tasks. If the servers you work with have CD drives, I would recommend burning these images onto a CD or DVD. This would save you the trouble of messing with the boot options in the BIOS. More advanced versions of BIOS can mount remote ISO images and boot from those. In most cases, however, this approach requires using the dreaded Internet Explorer an requires Windows.

Searching Large Network-Mounted Filesystems

Recently I ran into a small problem: I needed to find recently-modified files in a very large NFS filesystem. One of the high-level folders contained dozens of sub-folders with thousands of files in each. There is a significant performance penalty associated with placing such directory structures on network-mounted filesystems. Running the “find” command at the top of the filesystem would have taken over an hour and the problem here was not available bandwidth, but the time it takes for the “find” to request and receive attribute information for each folder and file.

Solaris 10 SVM/SDS Mirrored Root Disk Replacement

The following is a standard process for replacing a failed boot disk mirrored with SVM on a Solaris 10 Sun server. Your hardware must support hot-swappable disks for this process to be performed without booting into single-user mode.

Import CSV into Excel Spreadsheet via OLEDB

The following is a quick how-to explaining the process of importing an external CSV file into an existing Excel spreadsheet. This approach can be very handy if your CSV data is updated regularly by some external application. Keeping the formatting in the spreadsheet and pulling fresh data from a separate CSV is the way to go. The instructions below are for Excel 2010 running on Windows 7 64-bit. Command syntax for other versions of Excel and other platforms may differ.

Configure Postfix to Use Gmail for Sending

Here is a simple script to help you configure Linux postfix to use your Gmail account for sending emails. The script has been tested on OpenSuse 11.4 and 12.1, but should work find on any recent Linux disro. The only requirement is that you have postfix insalled.

Linux LVM: Reduce Filesystem and Logical Volume

The following example shows how to reduce the size of a filesystem mounted on an LVM logical volume. The instructions below are only for non-root filesystems. No reboot is required, but the filesystem will need to be unmounted. So, if there are any user applications using this filesystem, they will need to be stopped and the users will need to log out.

A Simple Process Monitoring Script

Let’s say you are running a data restore. Things are moving along, but network is congested and the backup server is overloaded. You really don’t feel staring at the restore status for the next several hours and just want to be notified when the process completes. The simplest method of monitoring for processes starting or ending on Unix systems is by using “ps” with a “while” loop.

Testing SSH Connectivity to Multiple Servers

Imagine a hypothetical scenario: you support hundreds of remote servers and you need to check which server you can access via SSH and which servers are not letting you log in. Doing this manually is a tedious process that many sysadmins choose to skip. The inevitable outcome is inability to quickly access a system when it really counts.

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