SORT, as the name implies is 'something' which sort the 'entities' (records) in some particular order. However over the years these sort products have been evolved as a "Software suite" in them selves.
The SORT utility, initially known as the Sort/Merge utility, in a crude sense is a mainframe program to sort records in a file into a specified order or copy selected records. SORT can also be used to merge pre-sorted files into a sorted file.
Mainframes were originally supplied with limited main memory by today's standards. The amount of data to be sorted was frequently very large.
Because of this, unlike more recent sort programs, early sort/merge programs placed great emphasis on efficient techniques for sorting data on
secondary storage, typically tape or disk. In 1968 the OS/360 Sort/Merge program provided five different "sequence distribution techniques" that
could be used depending on the number and type of devices available.
Sort/Merge is very frequently used; often the most commonly used application program in a mainframe shop.
Modern sort/merge programs also can copy files, select or omit certain records, summarize records, remove duplicates, reformat records, append new
data and produce reports. Indeed most "Sort/Merge" applications use the wide range of additional processing capabilities, rather than purely
sorting or merging records: The Sort/Merge product is a very fast way of performing input to and output from these functions.
Sort/merge is important enough that there are multiple companies each selling their own sort/merge package for IBM mainframes and their z/OS, z/VM and z/VSE operating systems.
