http://www.purl.org/tcl/home/man/tcl8.4/TclCmd/tclvars.htm
$::errorCode contains the exit status of the last exec or open "|..."/close pair that occured in the application.
DGP: 2002 Jan 17 Sorry, but that's just false. All Tcl errors write to ::errorCode; not only the ones from [exec] and [open].
See tclvars(n), error(n), and return(n).
Anyone have good programming practices for using this?
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