undef EXPR undef Undefines the value of EXPR, which must be an lvalue. Use only on a scalar value, an array

elseif The "else if" keyword is spelled elsif in Perl. There's no elif

sort SUBNAME LIST sort BLOCK LIST sort LIST In list context, this sorts

kill SIGNAL, LIST kill SIGNAL Sends a signal to a list of processes. Returns the number of arguments that

our VARLIST our TYPE VARLIST our VARLIST : ATTRS our TYPE VARLIST : ATTRS

open FILEHANDLE,EXPR open FILEHANDLE,MODE,EXPR open FILEHANDLE,MODE,EXPR,LIST open

qr/STRING/ Regexp-like quote. See Regexp Quote-Like Operators in