For a tool offering a SQL-like query and update language for CSV, TSV, LTSV, JSON, and fixed-width data files, readers should check out csvq. Users can extract subsets of the data using the familiar SELECT ... WHERE syntax; generate summaries with aggregate functions such as COUNT, AVG, MEDIAN, and others; or transform the structure of a data file with ALTER TABLE statements. Multiple operations can be handled as a group using csvq's interactive shell. Within these groups of operations, users can also make use of several familiar features from database systems, including variables, cursors, and temporary tables. The "Command Usage" section of the Reference Manual (in the menu on the left side of the page) describes the various ways that csvq can be invoked and gives examples of each. The remainder of the manual provides a detailed technical reference to the query language. The "Download" link on the page linked above provides binaries for Windows, macOS, Linux, and BSD systems.