Quoting and Character Escapes

The date format tokens in the following example, '+%a, %e %b %Y %T %Z', must appear to be a single unit (a word in shell speak) to the shell.

Without quotes or escapes, the space character between the format tokens will cause the command to fail.

The 5 date commands below are identical, but quoted/escaped differently.
on mouseup
put merge("date `+%a, %e %b %Y %T %Z` ; ") &¬
"date '+%a, %e %b %Y %T %Z' ; " &¬
"date +%a,' %e %b %Y %T '%Z ; " &¬
"date +%a,' '%e' '%b' '%Y' '%T' '%Z ; " &¬
"date +%a, %e %b %Y %T %Z ; " after cmd
--
alert Sheet shell(cmd)
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Much more on quoting and escape sequences to come.