Join lines of two sorted files by matching on a common field. If either file1 or file2 is -, read from standard input. Often used to merge data stored in text-based file formats such as comma-separated-value formatted spreadsheets.
The join field in file1 is fieldnum1. Default is the first field.
The join field in file2 is fieldnum2. Default is the first field.
Print a line for each unpairable line in file filenum, in addition to the normal output.
Check or do not check that the files are correctly sorted on the join fields.
Replace missing input fields with string.
Ignore case differences when comparing fields.
Order the output fields according to fieldlist, where each entry in the list is in the form filenum.fieldnum. Entries are separated by commas or blanks.
Specifies the field-separator character (default is whitespace).
Print only unpairable lines from file filenum.
Print help message and then exit.
Print the version number and then exit.