ullfilt

Ullfilt is a Unix-based data processing tool that filters and rearranges fields in a dataset. It was developed by Holden Carlson, a scientist at the U.S. Geological Survey (USGS), and first released in the early 1980s.

Ullfilt is primarily used in the field of Earth sciences to manipulate data from various hydrological and climatological sources. The tool reads in data from input files, rearranges the fields according to user-defined commands, and writes the output to new files. It is written in C and designed to be a flexible, efficient, and easy-to-use tool for data manipulation.

One of the key features of ullfilt is its ability to handle large datasets with multiple columns and rows. Users can specify the fields they want to keep or discard using a command-line format that combines optional and required fields. This allows for a high degree of customization and flexibility in data processing.

Ullfilt also includes a number of utility commands and functions to perform arithmetic operations, create new records, and work with missing values. These features make it a versatile tool for a variety of data manipulation tasks.

While ullfilt is still in use today in specific fields of Earth sciences, there are other more modern alternatives available that may offer additional functionality or improved features. Despite this, ullfilt remains a simple and effective tool for basic data manipulation tasks, and its command-line interface makes it easy to learn and integrate into existing workflows.