The argument which trails
%! until the end of the line, is
passed to the shell as a command for further processing. But before, all
text variable references and
%?… special texts for
replacing particular texts which are given in argument are
interpreted by Gcal.
See Text variables,
%?… special texts for text replacement.
All leading text before the
%! special text is processed
by Gcal as usual. If the simple --debug respectively
--debug=internal option is given at program start-up,
informational messages about the executed command and its exit code
will be shown on the standard error channel
(see Global option --debug=internal).
If the --debug=abort option is given, the Gcal program will be aborted with an error code in case an exit code not equal zero has occurred during the execution of the command. See Error Code 2, and Global option --debug=abort, for further information.
Use the --execute-command option if you want to execute all
%![argument] special texts by the shell instead of
seeing them textually only.
See Fixed date option --execute-command,
for more details.