Perl search and replace binary file
This is in the style of F77 and solves the usual problem of "how long is a piece of string" by choosing a size that is surely long enough. Perl search and replace binary file Q format code allows discovery of the length of a record as it is being read, and so only the required portion, ALINE 1: Lof an input record is placed and trailing spaces out to are not supplied nor need they be scanned.
Thus an input record that has trailing spaces will have them preserved - unless the text replacement changes spaces The search is done by perl search and replace binary file the supplied INDEX function which alas rarely has an option to specify the starting point via an additional optional? L ,THIS and then one must carefully consider offsets and the like while counting on fingers and becoming confused. L being shorter than THIS. L does not create a new string variable by copying the specified text, it works or should work!
Similarly, there is no attempt to concatenate an output string to write in one go as perl search and replace binary file too would involve copying text about. L be written out in one go, the more general approach is used of writing text up to the start of perl search and replace binary file match, writing out the replacement THAT, and scanning beyond the match for the next text until the tail end.
The file to be altered cannot be changed "in-place", as by writing back an altered record even if the text replacement does not involve a change in length because such a facility is not available for text files that are read and written sequentially only.
More accomplished file systems may well offer varying-length records with update possible even of longer or shorter new versions but standard Fortran perl search and replace binary file not demand such facilities.
So, the altered content has to be written to a temporary file or perhaps could be held in a capacious memory which is then read back to overwrite the original file. It would be safer to rename the original file and write to a new version, but Fortran typically does not have access to any file renaming facilities and the task calls for an overwrite anyway. So, overwrite it is, which is actually a file delete followed by a write.
List provides some useful functions: This code doesn't rewrite the files, it just returns the changes made to the contents of the files. This other version is more effective because it processes the string more lazily, replacing the text as it consumes the input string the previous version was stricter because of "matches" traversing the whole list; that would force the whole string into memory, perl search and replace binary file could cause the system to run out of memory with large text files.
This example uses the Unicon stat function. It can be rewritten for Icon to aggregate the file in a reads loop. Here is a string-oriented alternative:.
We will use Julia's built-in Perl-compatible regular-expressions. Although we could read in the files line by line, it is simpler and probably faster to just read the whole file into memory as text files are likely to fit into memory on modern computers. Current Perl 6 implementations do not yet support the -i flag for editing files in place, so we roll our own rather unsafe version:. File names that contain blanks should have their blanks replaced with commas. The apply2 method doesn't return anything, it is a side effects method.
Use this filter to find a text pattern. You can also use this filter to find multi-line text. The length of each string is shown above it, and a warning is displayed on the status line if they are not the same. This can be very useful when replacing strings in binary files.
The pattern to find. To capture data, simply enclose it in parentheses e. To capture data and also name it, use this syntax '? Pattern options button [ Default Match Length "Greediness". When set to maximal match, TextPipe will try to match the perl search and replace binary file against the perl search and replace binary file piece of text possible. When set to minimal match, TextPipe will try to match the pattern against the shortest piece of text possible. Minimal matching is the default and is the most often used, because it prevents the.
With a large maximum text buffer size, greedy matching can be very inefficient. This option inverts the "greediness" of the quantifiers so that they are not greedy by default, but become greedy if followed by "? It can also be set by a? U perl search and replace binary file setting within the pattern. Maximum Text Buffer Size. Changes the maximum search buffer size. If you need to match a string that is longer than bytes 4kincrease the Maximum text buffer size to be at least as large as the string you need to match.
The pattern matching engine is given a block of text to work with. This block of text is guaranteed by TextPipe to be at least 4K larger than the size of the "Maximum Text Buffer Size" - the block may be larger depending on what filters precede the pattern match filter.
Let's call this buffer size the 'critical size'. This critical size allows for efficient matching, because if the buffer is too large, the pattern matching engine may have to check many cases before it fails, so it is more efficient to perl search and replace binary file it fail earlier by having a smaller buffer size.
If greedy matching is turned on, having a larger buffer size may make matching very inefficient. Allow Comments In Pattern. This perl search and replace binary file Perl-style comments and extra white space to be included the pattern match.
White space data characters in the pattern are totally ignored except when escaped or inside a character class, and characters between an unescaped outside a character class and the next new line character, inclusive, are also ignored. This is very handy for including comments inside complicated patterns. Note, however, that this applies only to data characters.
White space characters may never appear within special character sequences in a pattern, for example within the sequence? When enabled default a dot metacharacter in the pattern matches all characters, including new lines.
Without it, new lines are excluded. Enables pattern matching in UTF-8 encoded data. If you search for the Unicode character. When checked, the case of the string found must match the case of the Perl search and replace binary file Pattern exactly. Find Whole Words Only. Only match the Find Pattern when it is not part of a larger word e. The text to replace the found text with. Named captured variables are stored in global macros e.
Macros can be inserted to provide the value of a global variable. If you capture data to named variables and then reference them in the Replace With string e. TextPipe detects a file being loaded from an older version and makes this change automatically. The replacement text is passed to any sub filters. The Action field defines what happens when the text is found.
The found text is sent to the subfilter for further processing, such as changing the capitalization. Non-matching text is sent to the subfilter for further processing, such as performing a replacement outside of HTML tags.
Captured variable X from 1 to 9 is sent to the subfilter for further processing. This is very handy for detecting text based on variable data stored around it, while leaving the variable data alone. It also avoids the need to use look ahead or look behind assertions in the pattern matching language, which are quite perl search and replace binary file and counter-intuitive hey, we didn't write that bit.
If the Find Pattern matches text that is entirely in lowercase, this forces the replace string to all lowercase. Only replace the first occurrence found - skip all remaining matches. By checking this option, you can manually verify each match before it gets replaced. You can choose to replace or ignore single matches, the remainder of the file or the entire job. Skip Prompt If Identical. If the find string and replace string are identical, this option can be enabled to skip prompting. This can happen when the case of the search string is identical to the case of the replace string during a case-insensitive search.
When this option is checked all non-matching text will be discarded, leaving only the replacement text. This can be handy for data mining content perl search and replace binary file web sites or data files. Find pattern perl-style The pattern to find. Special requirements Replace With text: With Captured Variables Results in: The found text is replaced with the new text Remove The found text is removed Send matching text to subfilter The found text is sent to the subfilter for further processing, such as changing the capitalization Send non-matching text to subfilter Non-matching text is sent to the subfilter for further processing, such as performing a replacement outside of HTML tags Send variable X to subfilter X varies from 1 to 9 Captured variable X from 1 to 9 is sent to the subfilter for further processing.
An Introduction to Pattern Matching. The found text is replaced with the new text. Send non-matching text to subfilter. Send variable Perl search and replace binary file to subfilter X varies from 1 to 9.
The syntax and semantics of the regular expressions that are supported by PCRE are described in detail perl search and replace binary file. There is a quick-reference syntax summary in the pcresyntax page.
PCRE tries to match Perl syntax and semantics as closely as it can. PCRE also supports some alternative regular expression syntax which does not conflict with the Perl syntax in order to provide some compatibility with regular expressions in Python.
Perl's regular expressions are described in its own documentation, and regular expressions in general are covered in a number of books, some of which have copious examples. This description of PCRE's regular expressions is intended as reference material. The original operation of PCRE was on strings of one-byte characters. However, there is perl search and replace binary file also support for UTF-8 strings in the original library, an extra library that supports bit and UTF character strings, and a third library that supports bit and UTF character strings.
To use these features, PCRE must be built to include appropriate support. There are also some more of these special sequences that are concerned with the handling of newlines; they are described below.
Some of the features discussed below are not available when DFA matching is used. The advantages and disadvantages of the alternative functions, and how they differ from the normal functions, are discussed in the pcrematching page. PCRE supports five different conventions for indicating line breaks in strings: The pcreapi page has further discussion about newlines, and shows how to set the newline convention in the options arguments for the compiling and matching functions.
It is also perl search and replace binary file to specify a newline convention by starting a pattern string with one of the following five sequences:. The newline convention affects where the circumflex and dollar assertions are true. By default, this is any Unicode newline sequence, for Perl compatibility. A regular expression is a pattern that is matched against a subject string from left to right.
Most characters stand for themselves in a pattern, and match the corresponding characters in the subject. As a trivial example, the pattern. The power of regular expressions comes from the ability to include alternatives and repetitions in the pattern. These are encoded in the pattern by the perl search and replace binary file of metacharacterswhich do not stand for themselves but instead are interpreted in some special way.
There are perl search and replace binary file different sets of metacharacters: Outside square brackets, the metacharacters are as follows:. The backslash character has several uses. Firstly, if it is followed by a character that is not a number or a letter, it takes away any special meaning that character may have.
This use of backslash as an escape character applies both inside perl search and replace binary file outside character classes. This escaping action applies whether or not the following character would otherwise be interpreted as a metacharacter, so it is always safe to precede a non-alphanumeric with backslash to specify that it stands for itself.
All other characters in particular, those whose codepoints are greater than are treated as literals. An escaping backslash can be used to include a white space or character as part of the perl search and replace binary file. Note the following examples:. A second use of backslash provides a way of encoding non-printing characters in patterns in a visible manner. There is no restriction on the appearance of non-printing characters, apart from the binary zero that terminates a pattern, but when a pattern is being perl search and replace binary file by text editing, it is often easier to use one of the following escape sequences than the binary character it represents:.
If the next character is a lower case letter, it is converted to upper case. Then the 0xc0 bits of the byte are inverted. Otherwise, it matches a literal "x" character. There is no difference in the way they are handled.
If there are fewer than two digits, just those that are present are used. Make sure you supply two digits after the initial zero if the pattern character that follows is itself an octal digit. The handling of a backslash followed by a digit other than 0 is complicated. Outside a character class, PCRE reads it and any following digits as a decimal number. If the number is less than 10, or if there have been at least that many previous capturing left parentheses in the expression, the entire sequence is taken as a back reference.
A description of how this works is given later, following the discussion of parenthesized subpatterns. Inside a character class, or if the decimal number is greater than 9 and there have not been that many capturing subpatterns, PCRE re-reads up to three octal digits following the backslash, and uses them to generate a data character. Any subsequent digits stand for themselves. The value of the character is constrained in the same way as characters specified in hexadecimal. All the sequences that define a single character value can be used both inside and outside character classes.
Outside a character class, these sequences have different meanings. By default, PCRE does not support these escape sequences. Back references are discussed later, following the discussion of parenthesized subpatterns. Details are discussed later. The former is a back reference; the latter is a subroutine call.
Each pair of lower and upper case escape sequences partitions the complete set of characters into two disjoint sets. Any given character matches one, and only one, of each pair. The sequences can appear both inside and outside character classes. They each match one character of the appropriate type. If the current matching point is at the end of the subject string, all of them fail, because there is no character to match.
In PCREit never does. A "word" character is an underscore or any character that is a letter or digit. By default, the definition of letters and digits is controlled by Perl search and replace binary file low-valued character tables, and may vary if locale-specific matching is taking place see "Locale support" in the pcreapi page.
The use of locales with Unicode is discouraged. These sequences retain their original meanings from before UTF support was available, mainly for efficiency reasons. The horizontal space characters are:. In other modes, two additional characters whose codepoints are greater perl search and replace binary file are added: Unicode character property support is not needed for these characters to be recognized. BSR is an abbrevation for "backslash R". It is also possible to specify these settings by starting a pattern string with one of the following sequences:.
When PCRE is built with Unicode character property support, three additional escape sequences that match characters with specific properties are available. When in 8-bit non-UTF-8 mode, these sequences are of course limited to testing characters whose codepoints are less thanbut they do work in this mode. The extra escape sequences are:. Sets of Unicode characters are defined as belonging to certain scripts.
A character from one of these sets can be matched using a script perl search and replace binary file. Each character has exactly one Unicode general category property, specified by a two-letter abbreviation. For compatibility with Perl, negation can be specified by including a circumflex between the opening brace and the property name.
In this case, in the absence of negation, the curly brackets in the escape sequence are optional; these two examples have the same effect:. Perl does not support the Cs property. No character that is in the Unicode table has the Cn unassigned property.
Instead, this property is assumed for any code point that is not in the Unicode table. Specifying caseless matching does not affect these escape sequences.
Matching characters by Unicode property is not fast, because PCRE has to do a multistage table lookup in order to find a character's property. Up to and including release 8. This simple definition was extended in Unicode to include more complicated kinds of composite character by giving each character a grapheme breaking property, and creating rules that use these properties to define the boundaries of extended grapheme clusters.
In releases of PCRE later than 8. Then it decides whether to add additional characters according to the following rules for ending a cluster:. Do not break Hangul a Korean script syllable sequences. Hangul characters are of five types: Do not end before extending characters or spacing marks. Characters with the "mark" property always have the "extend" grapheme breaking property.
For example, the pattern:. The final use of backslash is for certain simple assertions. An assertion specifies a condition that has to be met at a particular point in a match, perl search and replace binary file consuming any characters from the subject string.
The use of subpatterns for more complicated assertions is described below. The backslashed assertions are:. Thus, they are independent of perl search and replace binary file mode. In Perl, these can be different when the previously matched string was empty.
Because PCRE does just one match at a time, it cannot reproduce this behaviour. The circumflex and dollar metacharacters are zero-width assertions. That is, they test for a particular condition being true without consuming any characters from the subject string.
Outside a character class, in the default matching mode, the circumflex character is an assertion that is true only if the current matching point is at the start of the subject string.