The trace file contains information gathered by the prex command. The trace_file location is assumed to be relative to the directory from which you started prex. When no trace_file is specified, the default location is $TMPDIR/trace-pid where pid is the process ID of your program. If $TMPDIR is not set, /tmp is used.

When a program is traced, the trace file that is set at the start (the default or the -o name) is used for the life of the program.

The libraries argument contains the names of libraries to preload for your programs. It follows the LD_PRELOAD (see ld(1)) rules on how libraries should be specified and where they are found. Enclose the space-separated list of library names in double quotes.

When prex loads the program, the default library is libtnfprobe.so.1. You cannot use this option when attaching prex to an already-running process.

size is the size of the trace file in kilobytes (2¹⁰ bytes). The default size of a trace file is four megabytes. The minimum size that can be specified is 128 kilobytes.