http://www.purl.org/tcl/home/man/tcl8.4/TclCmd/tclvars.htm
$::errorCode contains error information in various cases (see the man page above); one of these cases is the exit status of the last exec or open "|..."/close pair that received an error.
DGP: 2002 Jan 17 All Tcl errors write to ::errorCode; not only the ones from [exec] and [open].
See also tclvars, error(n), and return.
Anyone have good programming practices for using this?
[To what category does this page belong?]