One subtlety of Perl is the difference between single and double quotes.

The statement, print '$foo\n'; would print the string:   $foo\n.   That is to say, six literal characters exactly as shown.

The statement, print "$foo\n"; would print whatever is the value of the variable $foo, followed by a newline.

What’s the difference ... the only difference?   The quote-marks.   Perl calls this process, interpolation.

If you say, print '\{';, notice the single quotes, then the two characters will be output literally:   a backslash followed by a curly-brace.   Whereas, in double quotes, the two-character sequence would be interpreted as a character-escape meaning, “one left curly-brace.”

Postscript:   So, how do you produce a backslash in a double-quoted string?   By using two backslashes.   “\\” is a character-escape corresponding to “a literal backslash.”

Fun with Perl:   What about ten literal backslashes in a row?   Here’s one way:   print '\' x 10;   The “x” operator is a handy thing indeed, sometimes.