The '''main script''' is the primary script that is executed by the interpreter, e.g. [tclsh] or [wish].



** Description **

One common technique is to have a script run a self test if it detects that it
is the main script.  Naive approaches only compare `[info script]` with `$[argv0]`.  A somewhat more robust approach that usually works with [pkg_mkIndex] looks only at the `[file tail]` of those two values.  The most robust approach fully normalizes those two values, including the last component, which a simple `[file normalize]` does not resolve.

The most complete approach:

======
if {[info exists argv0] && [
    file dirname [file normalize [info script]/...]] eq [
    file dirname [file normalize $argv0/...]]} {

    #do stuff
}
======

''[AMG]: I'm not sure I fully understand the purpose of the `/...` in this code.  From the above description, I'm assuming it's a dummy component so that [[[file normalize]]] resolves all components of the true path.''

A common and fairly robust approach:

======
if {[info exists argv0] && [file tail [info script]] eq [file tail $argv0]} {
    #do stuff
}
======

The negative approach, also quite common:

======
if {![info exists argv0] || [file tail [info script]] ne [file tail $argv0]} {
    return
}

# test/standalone code follows
======

The more simple and naive approach to detection method directly compares `[info script]` with `$[argv0]`:

======
if {[info exists argv0] && $argv0 eq [info script]} {
    #do stuff
}
======

or, as formulated in a [comp.lang.tcl] posting by [DKF]:

======
if {[string equal $::argv0 [info script]] || [array exists ::embed_args]} {
    main
} 
======

''[AMG]: Which posting would that be?  What is `::embed_args`?  It must be something specific to the script [DKF] was describing.''

** authors **

   [dkf]:   

   [CJL]:   ''[AMG]: I'm not sure who this is... is a full name available?  According to [http://www.intelius.com/results.php?ReportType=1&searchform=name&qf=cameron&qn=laird], it's not [Cameron Laird] whose middle initial is not J.''

   [PYK]:   

   [RS]:   

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