Chapter 5. SpecTcl's startup process

As SpecTcl starts it uses several scripts to both steer its startup and to setup any Tcl commands and user interfaces desired by the user. This chapter describes scripts that you can use to modify how SpecTcl starts and what it looks like once it has started.

SpecTcl relies on two script families during initialization and startup. Each script family is a script with a specific name. The script is searched for in a specific set of directories and all matching scripts are sourced.

The directories searched are in order:


The etc subdirectory of the SpecTcl installation directory. Scripts here are intended to be maintained by the installer andshould be used to set system defaults and provide services that are common to all users of SpecTcl system wide.

The user's home directory

Scripts here should be used to provide definitions and services common to all projects the user works on.

Working directory

Scripts here should be usd to provide definitions and services specific to the analysis that is run from that directory.

SpecTcl starts in two major phases; initialization and setup. The initialization family of scripts is called SpecTclInit.tcl. These scripts are invoked very early in SpecTcl's startup and ares used to define values that provide limits, hints and steering variables for SpecTcl's initialization and startup.

The variables that can be set in this file are:


SpecTcl 5.0 and later support two visualization programs, the original Xamine and the Root based Spectra. This variable selects the visualizer that will be used: spectra will start the Root based Spectra displayer while xamine will start the traditional Xamine displayer


The number of megabytes of display memory that will be allocated to the shared memory region that holds bulk spectrum data. If this value results in a shared memory region larger than one supported by the configuration of Linux, you will get an invalid parameter message.

On linux, the maximum size a shared memory region can have is configured by setting the kernel.shmmax configuration parameter. This can be done at boot time using the sysctl.conf mechanisms. If you administer your own linux system see the manpage for sysctl.conf


The CEvent array like object that is passed to event processors is given an initial size set by this value. The object will expand as needed to allow the parameter with the highest index to fit. Internally, SpecTcl recycles old CEvent objects so the initial value is not that important anymore.


SpecTcl will let event processors unpack several events before submitting them in a batch to the histogramming classes. This is intended to improve, somewhat the cache hit rate. This value determines the maximum number of events SpeTcl will allow the event processor pipeline to process before submitting them all to the histogrammer.


If your SpecTcl starts the TkCon command console, this variable sets the number of commands TkCon will retain in its command history.


If your SpecTcl starts the TkCon command console, this variable sets the number of byes of scrollback buffer that will be maintained.

Once SpecTcl is fully initialized, it sources the SpecTclRC.tcl family of scripts. This set of scripts can be used to define application specific commands, variables, parameters spectra as well as to provide a graphical user interface to make interacting with SpecTcl easier. The skeleton comes with a SpecTclRC.tcl. Feel free to use this as a starting point or to discard it.

The skeleton SpecTclRC.tcl does the following:

  1. Sets up a splash image that shows approximately how far along the setup process the script has progressed. The default splash image is the SpecTcl logo. The splash image can be changed by setting splashImage in the SpecTclInit.tcl file.

  2. Starts the base SpecTcl GUI which that lives in Tk's main to level GUI. This is just a bar of buttons. This button bar starts with buttons that clear all spectra and exit SpecTcl. You can pack additional buttons in the top level widget or create your own top level widget GUI.

  3. Provides some low level scripts that support writing Tcl scripts that can be sourced into restore spectrum and gate definitions for later runs of SpecTcl. These are described in the command reference guide.

  4. Provides some low level scripts that support listing parameters, spectra, gates and their applications in a more human readable form. Recall that SpecTcl's native parameters produce output that's designed for processing by Tcl scripts. Note that the More proc is also provided which can paginate the output of these scripts.

    These scripts are also documented in the command reference guide.

  5. Provides scripts that can copy simple cuts, contours and bands to a different parameter set. This allows you to create a single gate that can then be copied over and over again.

    These scripts are documented in the command reference guide.

  6. Starts the TkCon console. TkCon has sophisticated command editing capabilities. The tclsh/wish interpreter run on SpecTcl's stdin is not nearly as nice in that regard. Note that if you don't need a console (you can do everything you want in your GUI) you don't need to start this.

    TkCon was written by Jeff Hobbs currently at ActiveState. It has been modified for use with SpecTcl and is incorporated under the rather loose terms of its Bourbon Ware license. The terms of that license were satisified at the 13'th Tcl conference in Naperville, in 2006.

  7. Starts the SpecTcl default GUI. If you have another GUI you prefer by all means substitute it. The SpecTcl default GUI is described in this document at: Using the 'standard' SpecTcl GUI