Technology Insights

cut – Represent A Tab As The Delimiter With Linux cut Command

I have been using the cut command a lot recently to shed extra data from large text files. I typically use cut with a specific delimiter by activating the -d switch and I thought that the -d switch was required. It turns out that -d is not required and by default -d actually defaults to the delimiter being a tab. When you need to have a tab as the delimiter for cut you simply don’t specify the -d switch. Below I show a couple examples of a file trimmed down using cut with and without the -d switch as well as another way to convert tabs in a file to spaces which then will allow you to use the Linux cut command with the -d” ” switch.

Technology Insights

Expand A Partition That Is Part Of A Logical Volume Group While Server Is Running

I recently had a couple new CentOS Linux servers brought online at a colo that a company I work for uses. I had the colo do a very simple install of CentOS so I could handle the details without having to remove a bunch of packages we didn’t need. The servers have two one terabyte drives installed in a RAID 1 configuration which provides us with one terabyte of usable disk space and upon initial configuration had a logical volume group created with three logical volumes. Each of the logical volumes, which included /var, /usr, and /, only had two gigabytes of space so I needed to first expand those logical volumes and later will be creating a large logical volume used for database data. Below I describe expanding already existing logical volumes when there is room to grow in the logical volume group.