use String::ShellQuote;                        # this package almost n
+ever works
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I couldn't agree more with that comment: Problems with String::ShellQuote

Are you sure that tcsh uses the same quoting rules as bourne shells? If not, you are probably in trouble. I don't really know, but a quick Google search suggests that there are differences. I found a pirated copy of "Unix Power Tools" (third edition) that has an entire chapter named "Differences Between Bourne and C Shell Quoting". It lists three differences, of which at least two are relevant for String::ShellQuote. In csh, ! can only be quoted by a backslash, it keeps its special meaning even inside single quotes. And the csh needs a backslash before newlines inside single and double quotes, unlike bourne shells.

And by the way, shell_quote_best_effort() may damage data and hides errors. See Problems with String::ShellQuote.

Alexander