Some options take a parameter; with the single-letter form these must be given as separate arguments.
With the long form, they may be given by appending "=value" to the option.
Secondly, if invoked with the additional '-d' option, it should do exactly the opposite: read the compressed data from the standard input and produce uncompressed data on the standard output.
The latter requirement means that you must not use the '-d' option as a part of the PROG command invocation itself.
Several --checkpoint-action options can be specified. The supplied actions will be executed in the order of their appearance on the command line.
Using --checkpoint-action without --checkpoint will assume the default checkpoint interval of 10 records.
For example, the following commands are all equivalent: Use the archive's suffix to determine the compression program.