A call to oft2-estimator has the following syntax:
Usage: otf2-estimator [OPTION]...
This tool estimates the size of OTF2 events.
It will open a prompt to type in commands.

Options:
  -V, --version       Print version information.
  -h, --help          Print this help information.

Commands:
   list definitions              Lists all known definition names.
   list events                   Lists all known event names.
   list types                    Lists all known type names.
   set <DEFINITION> <NUMBER>     Specifies the number of definitions of a
                                 type of definitions.
   get DefChunkSize              Prints the estimated definition chunk size.
   get Timestamp                 Prints the size of a timestamp.
   get AttributeList [TYPES...]  Prints the estimated size for an attribute
                                 list with the given number of entries and
                                 types.
   get <EVENT> [ARGS...]         Prints the estimated size of records for
                                 <EVENT>.
   exit                          Exits the tool.

This tool provides a command line interface to the estimator API of the OTF2
library. It is based on a stream based protocol.  Commands are send to the
standard input stream of the program and the result is written to the standard
output stream of the program.  All definition and event names are in there
canonical CamelCase form.  Numbers are printed in decimal.  The TYPES are in
ALL_CAPS.  See the output of the appropriate 'list' commands.  Arguments are
separated with an arbitrary number of white space.  The 'get' commands are using
everything after the first white space separator verbatim as a key, which is
then printed in the output line and appended with the estimated size.

Here is a simple example.  We have at most 4 region definitions and one metric
definition.  We want to know the size of a timestamp, enter, and leave event,
and a metric event with 4 values.

cat <<EOC | otf2-estimator
set Region 4
set Metric 1
get Timestamp
get Enter
get Leave
get Metric  4
exit
EOC
Timestamp 9
Enter 3
Leave 3
Metric  4 44