+++ /dev/null
-This file contains the PCRE man page that described the pcretest program. Note
-that not all of the features of PCRE are available in the limited version that
-is built with Exim.
--------------------------------------------------------------------------------
-
-PCRETEST(1) PCRETEST(1)
-
-
-NAME
- pcretest - a program for testing Perl-compatible regular expressions.
-
-
-SYNOPSIS
-
- pcretest [options] [source] [destination]
-
- pcretest was written as a test program for the PCRE regular expression
- library itself, but it can also be used for experimenting with regular
- expressions. This document describes the features of the test program;
- for details of the regular expressions themselves, see the pcrepattern
- documentation. For details of the PCRE library function calls and their
- options, see the pcreapi documentation.
-
-
-OPTIONS
-
- -b Behave as if each regex has the /B (show bytecode) modifier;
- the internal form is output after compilation.
-
- -C Output the version number of the PCRE library, and all avail-
- able information about the optional features that are
- included, and then exit.
-
- -d Behave as if each regex has the /D (debug) modifier; the
- internal form and information about the compiled pattern is
- output after compilation; -d is equivalent to -b -i.
-
- -dfa Behave as if each data line contains the \D escape sequence;
- this causes the alternative matching function,
- pcre_dfa_exec(), to be used instead of the standard
- pcre_exec() function (more detail is given below).
-
- -help Output a brief summary these options and then exit.
-
- -i Behave as if each regex has the /I modifier; information
- about the compiled pattern is given after compilation.
-
- -m Output the size of each compiled pattern after it has been
- compiled. This is equivalent to adding /M to each regular
- expression. For compatibility with earlier versions of
- pcretest, -s is a synonym for -m.
-
- -o osize Set the number of elements in the output vector that is used
- when calling pcre_exec() or pcre_dfa_exec() to be osize. The
- default value is 45, which is enough for 14 capturing subex-
- pressions for pcre_exec() or 22 different matches for
- pcre_dfa_exec(). The vector size can be changed for individ-
- ual matching calls by including \O in the data line (see
- below).
-
- -p Behave as if each regex has the /P modifier; the POSIX wrap-
- per API is used to call PCRE. None of the other options has
- any effect when -p is set.
-
- -q Do not output the version number of pcretest at the start of
- execution.
-
- -S size On Unix-like systems, set the size of the runtime stack to
- size megabytes.
-
- -t Run each compile, study, and match many times with a timer,
- and output resulting time per compile or match (in millisec-
- onds). Do not set -m with -t, because you will then get the
- size output a zillion times, and the timing will be dis-
- torted. You can control the number of iterations that are
- used for timing by following -t with a number (as a separate
- item on the command line). For example, "-t 1000" would iter-
- ate 1000 times. The default is to iterate 500000 times.
-
- -tm This is like -t except that it times only the matching phase,
- not the compile or study phases.
-
-
-DESCRIPTION
-
- If pcretest is given two filename arguments, it reads from the first
- and writes to the second. If it is given only one filename argument, it
- reads from that file and writes to stdout. Otherwise, it reads from
- stdin and writes to stdout, and prompts for each line of input, using
- "re>" to prompt for regular expressions, and "data>" to prompt for data
- lines.
-
- The program handles any number of sets of input on a single input file.
- Each set starts with a regular expression, and continues with any num-
- ber of data lines to be matched against the pattern.
-
- Each data line is matched separately and independently. If you want to
- do multi-line matches, you have to use the \n escape sequence (or \r or
- \r\n, etc., depending on the newline setting) in a single line of input
- to encode the newline sequences. There is no limit on the length of
- data lines; the input buffer is automatically extended if it is too
- small.
-
- An empty line signals the end of the data lines, at which point a new
- regular expression is read. The regular expressions are given enclosed
- in any non-alphanumeric delimiters other than backslash, for example:
-
- /(a|bc)x+yz/
-
- White space before the initial delimiter is ignored. A regular expres-
- sion may be continued over several input lines, in which case the new-
- line characters are included within it. It is possible to include the
- delimiter within the pattern by escaping it, for example
-
- /abc\/def/
-
- If you do so, the escape and the delimiter form part of the pattern,
- but since delimiters are always non-alphanumeric, this does not affect
- its interpretation. If the terminating delimiter is immediately fol-
- lowed by a backslash, for example,
-
- /abc/\
-
- then a backslash is added to the end of the pattern. This is done to
- provide a way of testing the error condition that arises if a pattern
- finishes with a backslash, because
-
- /abc\/
-
- is interpreted as the first line of a pattern that starts with "abc/",
- causing pcretest to read the next line as a continuation of the regular
- expression.
-
-
-PATTERN MODIFIERS
-
- A pattern may be followed by any number of modifiers, which are mostly
- single characters. Following Perl usage, these are referred to below
- as, for example, "the /i modifier", even though the delimiter of the
- pattern need not always be a slash, and no slash is used when writing
- modifiers. Whitespace may appear between the final pattern delimiter
- and the first modifier, and between the modifiers themselves.
-
- The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
- PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com-
- pile() is called. These four modifier letters have the same effect as
- they do in Perl. For example:
-
- /caseless/i
-
- The following table shows additional modifiers for setting PCRE options
- that do not correspond to anything in Perl:
-
- /A PCRE_ANCHORED
- /C PCRE_AUTO_CALLOUT
- /E PCRE_DOLLAR_ENDONLY
- /f PCRE_FIRSTLINE
- /J PCRE_DUPNAMES
- /N PCRE_NO_AUTO_CAPTURE
- /U PCRE_UNGREEDY
- /X PCRE_EXTRA
- /<cr> PCRE_NEWLINE_CR
- /<lf> PCRE_NEWLINE_LF
- /<crlf> PCRE_NEWLINE_CRLF
- /<anycrlf> PCRE_NEWLINE_ANYCRLF
- /<any> PCRE_NEWLINE_ANY
-
- Those specifying line ending sequencess are literal strings as shown.
- This example sets multiline matching with CRLF as the line ending
- sequence:
-
- /^abc/m<crlf>
-
- Details of the meanings of these PCRE options are given in the pcreapi
- documentation.
-
- Finding all matches in a string
-
- Searching for all possible matches within each subject string can be
- requested by the /g or /G modifier. After finding a match, PCRE is
- called again to search the remainder of the subject string. The differ-
- ence between /g and /G is that the former uses the startoffset argument
- to pcre_exec() to start searching at a new point within the entire
- string (which is in effect what Perl does), whereas the latter passes
- over a shortened substring. This makes a difference to the matching
- process if the pattern begins with a lookbehind assertion (including \b
- or \B).
-
- If any call to pcre_exec() in a /g or /G sequence matches an empty
- string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
- flags set in order to search for another, non-empty, match at the same
- point. If this second match fails, the start offset is advanced by
- one, and the normal match is retried. This imitates the way Perl han-
- dles such cases when using the /g modifier or the split() function.
-
- Other modifiers
-
- There are yet more modifiers for controlling the way pcretest operates.
-
- The /+ modifier requests that as well as outputting the substring that
- matched the entire pattern, pcretest should in addition output the
- remainder of the subject string. This is useful for tests where the
- subject contains multiple copies of the same substring.
-
- The /B modifier is a debugging feature. It requests that pcretest out-
- put a representation of the compiled byte code after compilation. Nor-
- mally this information contains length and offset values; however, if
- /Z is also present, this data is replaced by spaces. This is a special
- feature for use in the automatic test scripts; it ensures that the same
- output is generated for different internal link sizes.
-
- The /L modifier must be followed directly by the name of a locale, for
- example,
-
- /pattern/Lfr_FR
-
- For this reason, it must be the last modifier. The given locale is set,
- pcre_maketables() is called to build a set of character tables for the
- locale, and this is then passed to pcre_compile() when compiling the
- regular expression. Without an /L modifier, NULL is passed as the
- tables pointer; that is, /L applies only to the expression on which it
- appears.
-
- The /I modifier requests that pcretest output information about the
- compiled pattern (whether it is anchored, has a fixed first character,
- and so on). It does this by calling pcre_fullinfo() after compiling a
- pattern. If the pattern is studied, the results of that are also out-
- put.
-
- The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
- that is, both the /B and the /I modifiers.
-
- The /F modifier causes pcretest to flip the byte order of the fields in
- the compiled pattern that contain 2-byte and 4-byte numbers. This
- facility is for testing the feature in PCRE that allows it to execute
- patterns that were compiled on a host with a different endianness. This
- feature is not available when the POSIX interface to PCRE is being
- used, that is, when the /P pattern modifier is specified. See also the
- section about saving and reloading compiled patterns below.
-
- The /S modifier causes pcre_study() to be called after the expression
- has been compiled, and the results used when the expression is matched.
-
- The /M modifier causes the size of memory block used to hold the com-
- piled pattern to be output.
-
- The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
- rather than its native API. When this is done, all other modifiers
- except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present,
- and REG_NEWLINE is set if /m is present. The wrapper functions force
- PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
-
- The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
- set. This turns on support for UTF-8 character handling in PCRE, pro-
- vided that it was compiled with this support enabled. This modifier
- also causes any non-printing characters in output strings to be printed
- using the \x{hh...} notation if they are valid UTF-8 sequences.
-
- If the /? modifier is used with /8, it causes pcretest to call
- pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the
- checking of the string for UTF-8 validity.
-
-
-DATA LINES
-
- Before each data line is passed to pcre_exec(), leading and trailing
- whitespace is removed, and it is then scanned for \ escapes. Some of
- these are pretty esoteric features, intended for checking out some of
- the more complicated features of PCRE. If you are just testing "ordi-
- nary" regular expressions, you probably don't need any of these. The
- following escapes are recognized:
-
- \a alarm (BEL, \x07)
- \b backspace (\x08)
- \e escape (\x27)
- \f formfeed (\x0c)
- \n newline (\x0a)
- \qdd set the PCRE_MATCH_LIMIT limit to dd
- (any number of digits)
- \r carriage return (\x0d)
- \t tab (\x09)
- \v vertical tab (\x0b)
- \nnn octal character (up to 3 octal digits)
- \xhh hexadecimal character (up to 2 hex digits)
- \x{hh...} hexadecimal character, any number of digits
- in UTF-8 mode
- \A pass the PCRE_ANCHORED option to pcre_exec()
- or pcre_dfa_exec()
- \B pass the PCRE_NOTBOL option to pcre_exec()
- or pcre_dfa_exec()
- \Cdd call pcre_copy_substring() for substring dd
- after a successful match (number less than 32)
- \Cname call pcre_copy_named_substring() for substring
- "name" after a successful match (name termin-
- ated by next non alphanumeric character)
- \C+ show the current captured substrings at callout
- time
- \C- do not supply a callout function
- \C!n return 1 instead of 0 when callout number n is
- reached
- \C!n!m return 1 instead of 0 when callout number n is
- reached for the nth time
- \C*n pass the number n (may be negative) as callout
- data; this is used as the callout return value
- \D use the pcre_dfa_exec() match function
- \F only shortest match for pcre_dfa_exec()
- \Gdd call pcre_get_substring() for substring dd
- after a successful match (number less than 32)
- \Gname call pcre_get_named_substring() for substring
- "name" after a successful match (name termin-
- ated by next non-alphanumeric character)
- \L call pcre_get_substringlist() after a
- successful match
- \M discover the minimum MATCH_LIMIT and
- MATCH_LIMIT_RECURSION settings
- \N pass the PCRE_NOTEMPTY option to pcre_exec()
- or pcre_dfa_exec()
- \Odd set the size of the output vector passed to
- pcre_exec() to dd (any number of digits)
- \P pass the PCRE_PARTIAL option to pcre_exec()
- or pcre_dfa_exec()
- \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
- (any number of digits)
- \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
- \S output details of memory get/free calls during matching
- \Z pass the PCRE_NOTEOL option to pcre_exec()
- or pcre_dfa_exec()
- \? pass the PCRE_NO_UTF8_CHECK option to
- pcre_exec() or pcre_dfa_exec()
- \>dd start the match at offset dd (any number of digits);
- this sets the startoffset argument for pcre_exec()
- or pcre_dfa_exec()
- \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
- or pcre_dfa_exec()
- \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
- or pcre_dfa_exec()
- \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
- or pcre_dfa_exec()
- \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
- or pcre_dfa_exec()
- \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
- or pcre_dfa_exec()
-
- The escapes that specify line ending sequences are literal strings,
- exactly as shown. No more than one newline setting should be present in
- any data line.
-
- A backslash followed by anything else just escapes the anything else.
- If the very last character is a backslash, it is ignored. This gives a
- way of passing an empty line as data, since a real empty line termi-
- nates the data input.
-
- If \M is present, pcretest calls pcre_exec() several times, with dif-
- ferent values in the match_limit and match_limit_recursion fields of
- the pcre_extra data structure, until it finds the minimum numbers for
- each parameter that allow pcre_exec() to complete. The match_limit num-
- ber is a measure of the amount of backtracking that takes place, and
- checking it out can be instructive. For most simple matches, the number
- is quite small, but for patterns with very large numbers of matching
- possibilities, it can become large very quickly with increasing length
- of subject string. The match_limit_recursion number is a measure of how
- much stack (or, if PCRE is compiled with NO_RECURSE, how much heap)
- memory is needed to complete the match attempt.
-
- When \O is used, the value specified may be higher or lower than the
- size set by the -O command line option (or defaulted to 45); \O applies
- only to the call of pcre_exec() for the line in which it appears.
-
- If the /P modifier was present on the pattern, causing the POSIX wrap-
- per API to be used, the only option-setting sequences that have any
- effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively,
- to be passed to regexec().
-
- The use of \x{hh...} to represent UTF-8 characters is not dependent on
- the use of the /8 modifier on the pattern. It is recognized always.
- There may be any number of hexadecimal digits inside the braces. The
- result is from one to six bytes, encoded according to the UTF-8 rules.
-
-
-THE ALTERNATIVE MATCHING FUNCTION
-
- By default, pcretest uses the standard PCRE matching function,
- pcre_exec() to match each data line. From release 6.0, PCRE supports an
- alternative matching function, pcre_dfa_test(), which operates in a
- different way, and has some restrictions. The differences between the
- two functions are described in the pcrematching documentation.
-
- If a data line contains the \D escape sequence, or if the command line
- contains the -dfa option, the alternative matching function is called.
- This function finds all possible matches at a given point. If, however,
- the \F escape sequence is present in the data line, it stops after the
- first match is found. This is always the shortest possible match.
-
-
-DEFAULT OUTPUT FROM PCRETEST
-
- This section describes the output when the normal matching function,
- pcre_exec(), is being used.
-
- When a match succeeds, pcretest outputs the list of captured substrings
- that pcre_exec() returns, starting with number 0 for the string that
- matched the whole pattern. Otherwise, it outputs "No match" or "Partial
- match" when pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR-
- TIAL, respectively, and otherwise the PCRE negative error number. Here
- is an example of an interactive pcretest run.
-
- $ pcretest
- PCRE version 7.0 30-Nov-2006
-
- re> /^abc(\d+)/
- data> abc123
- 0: abc123
- 1: 123
- data> xyz
- No match
-
- If the strings contain any non-printing characters, they are output as
- \0x escapes, or as \x{...} escapes if the /8 modifier was present on
- the pattern. See below for the definition of non-printing characters.
- If the pattern has the /+ modifier, the output for substring 0 is fol-
- lowed by the the rest of the subject string, identified by "0+" like
- this:
-
- re> /cat/+
- data> cataract
- 0: cat
- 0+ aract
-
- If the pattern has the /g or /G modifier, the results of successive
- matching attempts are output in sequence, like this:
-
- re> /\Bi(\w\w)/g
- data> Mississippi
- 0: iss
- 1: ss
- 0: iss
- 1: ss
- 0: ipp
- 1: pp
-
- "No match" is output only if the first match attempt fails.
-
- If any of the sequences \C, \G, or \L are present in a data line that
- is successfully matched, the substrings extracted by the convenience
- functions are output with C, G, or L after the string number instead of
- a colon. This is in addition to the normal full list. The string length
- (that is, the return from the extraction function) is given in paren-
- theses after each string for \C and \G.
-
- Note that whereas patterns can be continued over several lines (a plain
- ">" prompt is used for continuations), data lines may not. However new-
- lines can be included in data by means of the \n escape (or \r, \r\n,
- etc., depending on the newline sequence setting).
-
-
-OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
-
- When the alternative matching function, pcre_dfa_exec(), is used (by
- means of the \D escape sequence or the -dfa command line option), the
- output consists of a list of all the matches that start at the first
- point in the subject where there is at least one match. For example:
-
- re> /(tang|tangerine|tan)/
- data> yellow tangerine\D
- 0: tangerine
- 1: tang
- 2: tan
-
- (Using the normal matching function on this data finds only "tang".)
- The longest matching string is always given first (and numbered zero).
-
- If /g is present on the pattern, the search for further matches resumes
- at the end of the longest match. For example:
-
- re> /(tang|tangerine|tan)/g
- data> yellow tangerine and tangy sultana\D
- 0: tangerine
- 1: tang
- 2: tan
- 0: tang
- 1: tan
- 0: tan
-
- Since the matching function does not support substring capture, the
- escape sequences that are concerned with captured substrings are not
- relevant.
-
-
-RESTARTING AFTER A PARTIAL MATCH
-
- When the alternative matching function has given the PCRE_ERROR_PARTIAL
- return, indicating that the subject partially matched the pattern, you
- can restart the match with additional subject data by means of the \R
- escape sequence. For example:
-
- re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
- data> 23ja\P\D
- Partial match: 23ja
- data> n05\R\D
- 0: n05
-
- For further information about partial matching, see the pcrepartial
- documentation.
-
-
-CALLOUTS
-
- If the pattern contains any callout requests, pcretest's callout func-
- tion is called during matching. This works with both matching func-
- tions. By default, the called function displays the callout number, the
- start and current positions in the text at the callout time, and the
- next pattern item to be tested. For example, the output
-
- --->pqrabcdef
- 0 ^ ^ \d
-
- indicates that callout number 0 occurred for a match attempt starting
- at the fourth character of the subject string, when the pointer was at
- the seventh character of the data, and when the next pattern item was
- \d. Just one circumflex is output if the start and current positions
- are the same.
-
- Callouts numbered 255 are assumed to be automatic callouts, inserted as
- a result of the /C pattern modifier. In this case, instead of showing
- the callout number, the offset in the pattern, preceded by a plus, is
- output. For example:
-
- re> /\d?[A-E]\*/C
- data> E*
- --->E*
- +0 ^ \d?
- +3 ^ [A-E]
- +8 ^^ \*
- +10 ^ ^
- 0: E*
-
- The callout function in pcretest returns zero (carry on matching) by
- default, but you can use a \C item in a data line (as described above)
- to change this.
-
- Inserting callouts can be helpful when using pcretest to check compli-
- cated regular expressions. For further information about callouts, see
- the pcrecallout documentation.
-
-
-NON-PRINTING CHARACTERS
-
- When pcretest is outputting text in the compiled version of a pattern,
- bytes other than 32-126 are always treated as non-printing characters
- are are therefore shown as hex escapes.
-
- When pcretest is outputting text that is a matched part of a subject
- string, it behaves in the same way, unless a different locale has been
- set for the pattern (using the /L modifier). In this case, the
- isprint() function to distinguish printing and non-printing characters.
-
-
-SAVING AND RELOADING COMPILED PATTERNS
-
- The facilities described in this section are not available when the
- POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
- ifier is specified.
-
- When the POSIX interface is not in use, you can cause pcretest to write
- a compiled pattern to a file, by following the modifiers with > and a
- file name. For example:
-
- /pattern/im >/some/file
-
- See the pcreprecompile documentation for a discussion about saving and
- re-using compiled patterns.
-
- The data that is written is binary. The first eight bytes are the
- length of the compiled pattern data followed by the length of the
- optional study data, each written as four bytes in big-endian order
- (most significant byte first). If there is no study data (either the
- pattern was not studied, or studying did not return any data), the sec-
- ond length is zero. The lengths are followed by an exact copy of the
- compiled pattern. If there is additional study data, this follows imme-
- diately after the compiled pattern. After writing the file, pcretest
- expects to read a new pattern.
-
- A saved pattern can be reloaded into pcretest by specifing < and a file
- name instead of a pattern. The name of the file must not contain a <
- character, as otherwise pcretest will interpret the line as a pattern
- delimited by < characters. For example:
-
- re> </some/file
- Compiled regex loaded from /some/file
- No study data
-
- When the pattern has been loaded, pcretest proceeds to read data lines
- in the usual way.
-
- You can copy a file written by pcretest to a different host and reload
- it there, even if the new host has opposite endianness to the one on
- which the pattern was compiled. For example, you can compile on an i86
- machine and run on a SPARC machine.
-
- File names for saving and reloading can be absolute or relative, but
- note that the shell facility of expanding a file name that starts with
- a tilde (~) is not available.
-
- The ability to save and reload files in pcretest is intended for test-
- ing and experimentation. It is not intended for production use because
- only a single pattern can be written to a file. Furthermore, there is
- no facility for supplying custom character tables for use with a
- reloaded pattern. If the original pattern was compiled with custom
- tables, an attempt to match a subject string using a reloaded pattern
- is likely to cause pcretest to crash. Finally, if you attempt to load
- a file that is not in the correct format, the result is undefined.
-
-
-SEE ALSO
-
- pcre(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcrepartial(d),
- pcrepattern(3), pcreprecompile(3).
-
-
-AUTHOR
-
- Philip Hazel
- University Computing Service
- Cambridge CB2 3QH, England.
-
-
-REVISION
-
- Last updated: 24 April 2007
- Copyright (c) 1997-2007 University of Cambridge.
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