Re^2: passing newline in string argument

But what if someone actually wants to provide the two characters \n?

Special_K, just for completeness, here's one common way - however, as we both said, this is only a workaround with its own caveats, and the problem should be fixed in the shell instead!

sub interpolate_nl {
    my $str = shift;
    $str =~ s/(?<!\\)(?:\\\\)*\K\\n/\n/g;
    $str =~ s/\\\\/\\/g;
    return $str;
    # on 5.14 and above, the above can be compacted to:
    #shift =~ s/(?<!\\)(?:\\\\)*\K\\n/\n/gr =~ s/\\\\/\\/gr
}

use Test::More tests=>9;
is interpolate_nl("a\\b"),          "a\\b";    # *
is interpolate_nl("a\\nb"),         "a\nb";
is interpolate_nl("a\\\\b"),        "a\\b";
is interpolate_nl("a\\\\nb"),       "a\\nb";
is interpolate_nl("a\\\\\\b"),      "a\\\\b";  # *
is interpolate_nl("a\\\\\\nb"),     "a\\\nb";
is interpolate_nl("a\\\\\\\\b"),    "a\\\\b";
is interpolate_nl("a\\\\\\\\nb"),   "a\\\\nb";
is interpolate_nl("a\\\\\\\\\\nb"), "a\\\\\nb";
# * \b and all other escapes are unhandled and ignored!
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(Bonus: even more rope to shoot yourself in the foot: String::Unescape)

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