Why those command is not working?

cp letters$/$let$?.$doc work$/$misc$/$

mv work$/$misc$/$let$1.$doc work$/$misc$/$rpt$1.$doc

mv work$/$misc$/$let$2.$doc work$/$misc$/$rpt$2.$doc

mv work$/$misc$/$let$3.$doc work$/$misc$/$rpt$3.$docCopy using the $?$ wildcard the three files let$1.$doc, let$2.$doc, and let$3.$doc from the letters directory to the work$/$misc directory. Once copied, rename the new files $($the ones in the misc directory$)$ into rpt$1.$doc, rpt$2.$doc, and rpt$3.$doc. When renaming, you have to do this explicitly and not try to use a wildcard. It would appear at first that a wildcard could make the renaming easier, but it turns out to be ridiculously hard to use a wildcard in this case.

Tests: Complete

letters$/$let$1.$doc $->$ work$/$misc$/$rpt$1.$doc FAILED

letters$/$let$2.$doc $->$ work$/$misc$/$rpt$2.$doc FAILED

letters$/$let$3.$doc $->$ work$/$misc$/$rpt$3.$doc FAILEDKernel $3\mathrm{.}10\mathrm{.}0-514\mathrm{.}10\mathrm{.}2.$el$7.$x$86\_64$ on an x$86\_64$

host$-2-193$ login: demo

Password:

Last login: Sun Feb $2520$:$54$:$27$ from hub$1-$gw

$[$demo@host$-2-193]$ cp letters$/$let$?.$doc work$/$misc$/$

cp: cannot stat 'letters$/$let$?.$doc': No such file or directory

$[$demo@host$-2-193]$ mv work$/$misc$/$let$1.$doc work$/$misc$/$rpt$1.$doc

mv: cannot stat 'work$/$misc$/$let$1.$doc': No such file or directory

$[$demo@host$-2-193]$ $ mv work$/$misc$/$let$2.$doc work$/$misc$/$rpt$2.$doc

mv: cannot stat 'work$/$misc$/$let$2.$doc': No such file or directory

$[$demo@host$-2-193]$ $ mv work$/$misc$/$let$3.$doc work$/$misc$/$rpt$3.$doc

mv: cannot stat 'work$/$misc$/$let$3.$doc': No such file or directory

$[$demo@host$-2-193]$ $