Perl Pattern Search and Replace

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.

Find pattern (perl-style)

Pattern options button [...]

Default Match Length ("Greediness")

When set to maximal match, TextPipe will try to match the pattern against the longest 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 .* operator from matching an end tag at the end of the file rather than the very next one, and for this reason it is generally much faster than a maximal match. 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) option 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 4096 bytes (4k), increase the Maximum text buffer size to be at least as large as the string you need to match.

Technical Notes:

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 make 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 enables 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 (?( which introduces a conditional sub pattern.

'.' Matches Newline

When enabled (default) a dot metacharacter in the pattern matches all characters, including new lines. Without it, new lines are excluded. A negative class such as [^a] always matches a new line character, independent of the setting of this option.

Enable UTF-8 Support

Enables pattern matching in UTF-8 encoded data.

Match Case

When checked, the case of the string found must match the case of the Find Pattern exactly.

Find Whole Words Only

Only match the Find Pattern when it is not part of a larger word e.g. find "the" but not "them", "there", "worth" etc.

Replace With

The text to replace the found text with. The right-click (or context) menu on this field supports Undo, Cut, Copy, Paste, Delete, Clear Entire Field, Select All and Select All And Copy, entering unprintable and special characters and inserting pattern replacement specifiers:

If you need to put a dollar sign $ in the Replace With section, simply double it i.e. $$.

Case Sensitive Replace

If the Find Pattern matches text that is entirely in UPPERCASE, this forces the replace string to all UPPERCASE. If the Find Pattern matches text that is entirely in lowercase, this forces the replace string to all lowercase.

Replace First Only

Prompt On Replace

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.

Extract matches

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 from web sites or data files.