After execution, many Tcl commands return a result string, which is echoed to the terminal when the command is entered on the command line. When writing complex Tcl scripts, this result can be stored and/or used as a test in loops, etc. When XSPEC commands are executed, they write information to the terminal in one of two ways : either via the result string, as mentioned above, or by writing directly to the appropriate output channel. When it make sense, XSPEC commands return their information in the result string. In cases where it is not clear what information is being returned in the result string and what is being written directly to the terminal, one can use the following construct :
XSPEC> puts "*****\n[<xspec_command>]"
Anything printed after the ***** is part of the <xspec_command> result string.