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PDGREPPE Escape Byte

Escaped bytes are ones that have been converted to some other
value.

If the byte was originally magic, then an escape makes it
NON-magic.

If the byte was originally NON-magic, an escape makes it magic,
if the byte is recognised by PDGREPPE as one of its magic
symbols.  Otherwise it retains its normal value.

To escape a byte use a standard backslash '\'.


	pdgreppe -Hjc -1 "." file_id.diz


...will find the first (-1) ANY "." byte on each non-empty line of
file_id.diz


	pdgreppe -Hjc -1 "\." file_id.diz


...will find the period "." bytes in file_id.diz because the
magic symbol "." has been escaped by "\" to become "\.".

Options -E and -jX<d>:

To assist in the entry of LITERAL BYTES, that resemble MAGIC
SYMBOLS, the option "-E" may be given on the command line, in
which case any Magic Character is expected to be escaped, e.g.
"\?" to become magic.

The option "-E" is useful when entering bytes as literal bytes
(bytes that just represent themselves) that would otherwise
be considered magic like any of

[^$[].(){}<>#%-/;!?*+&|~`'@:,=]

AND at the same time entering a few MAGIC symbols that can be
escaped with the backslash character (\).

 \<char> next character in [^$[].(){}<>#%-/;!?*+&|~`'@:,=] is MAGIC (option -E)

 \<char> next character in [^$[].(){}<>#%-/;!?*+&|~`'@:,=] is Literal


	pdgreppe -Hjc "^$[].(){}<>#%-/;!?*+&|~`'@:,=" ere.def


...search for literal "^$[].(){}<>#%-/;!?*+&|~`'@:,=" does NOT work
because there are MAGIC rules for using MAGIC symbols (any of
^$[].(){}<>#%-/;!?*+&|~`'@:,=).


	pdgreppe -Hjc -E "^$[].(){}<>#%-/;!?*+&|~`'@:,=" ere.def


..."^$[].(){}<>#%-/;!?*+&|~`'@:,="

finds

	"^$[].(){}<>#%-/;!?*+&|~`'@:,="

because it is now a literal string by option -E.


	pdgreppe -Hjc "\^\$\[\]\.\(\)\{\}\<\>\#\%\-\/\;\!\?\*\+\&\|\~\`\'\@\:\,\=" ere.def


..."\^\$\[\]\.\(\)\{\}\<\>\#\%\-\/\;\!\?\*\+\&\|\~\`\'\@\:\,\=" finds
"^$[].(){}<>#%-/;!?*+&|~`'@:,=" because it is now a literal string
WITHOUT option -E and with each MAGIC character escaped by "\".

Another way to have any magic character in

	[^$[].(){}<>#%-/;!?*+&|~`'@:,=] or \

or non-magic character in

	["_]

be interpreted as a literal character is to use its decimal
character number as shown by using PDGREPPE with option -I:

 Special Character Decimal Numbers

 Magic Symbol Escape Numbers:

 !	\033	Exclamation Point
 #	\035	Hash Mark
 $	\036	Dollar Sign
 %	\037	Percent Sign
 &	\038	Ampersand
 '	\039	Trailing Single Quote
 (	\040	Left Parenthesis
 )	\041	Right Parenthesis
 *	\042	Asterisk
 +	\043	Plus Sign
 ,	\044	Comma
 -	\045	Minus Sign or Hyphen
 .	\046	Period or Full Stop
 /	\047	Forward Slash or Division Sign
 :	\058	Colon
 ;	\059	Semi-Colon
 <	\060	Left Pointer or Less-Than Sign
 =	\061	Equal Sign
 >	\062	Right Pointer or Greater-Than Sign
 ?	\063	Question Mark
 @	\064	At Symbol
 [	\091	Left Square Bracket
 \	\092	Back Slash
 ]	\093	Right Square Bracket
 ^	\094	Caret or Exponent Sign
 `	\096	Leading Single Quote
 {	\123	Left Curly Brace
 |	\124	Pipe Sign
 }	\125	Right Curly Brace
 ~	\126	Tilde

 Non-Magic Symbol Escape Numbers:

 "	\034	Double Quote
 _	\095	Underline


	pdgreppe -Hjc "\33\63\42\43" ere.def


..."\33\63\42\43" finds "!?*+" because the pattern is a literal
string with each MAGIC Quantity character given as a decimal
number "\<n>".

"	\034

One way to get around putting a double quote character into a
command line option is to use its escaped number equivalent
of \34 or \034 or simply \Q.

Also, the option

-jX<d>	  eXclude <d> of "^$[].(){}<>#%-/;!?*+&|~`'@:,=" from Magic like -E.

specifies a subset of magic symbols to be excluded from being
magic.

(If -jX<d> is used in conjunction with -E then <d> of -jX<d>
specifies the symbols that ARE considered Magic.)

Note:

If the last byte in a Command Line Pattern is a BackSlash that
is not ITSELF escaped by another single BackSlash, then the
BackSlash is entered as itself.

Also:

See the PDL Pattern Definition Language section on the use of
the BackSlash.
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