Entrez Direct: E-utilities on the Unix Command Line

Entrez Direct (EDirect) provides access to the NCBI's suite of inter-
connected databases (publication, sequence, structure, gene, variation,
expression, etc.) from a Unix terminal window. Search terms are entered
as command-line arguments. Individual operations are connected with Unix
pipes to construct multi-step queries. Selected records can then be
retrieved in a variety of formats.
