libraries/spcre/libpcre/pcre/doc/pcretest.txt
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+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.
+
+       When  pcretest  is  built,  a  configuration option can specify that it
+       should be linked with the libreadline library. When this  is  done,  if
+       the input is from a terminal, it is read using the readline() function.
+       This provides line-editing and history facilities. The output from  the
+       -help option states whether or not readline() will be used.
+
+       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
+         /<JS>           PCRE_JAVASCRIPT_COMPAT
+         /<cr>           PCRE_NEWLINE_CR
+         /<lf>           PCRE_NEWLINE_LF
+         /<crlf>         PCRE_NEWLINE_CRLF
+         /<anycrlf>      PCRE_NEWLINE_ANYCRLF
+         /<any>          PCRE_NEWLINE_ANY
+         /<bsr_anycrlf>  PCRE_BSR_ANYCRLF
+         /<bsr_unicode>  PCRE_BSR_UNICODE
+
+       Those  specifying  line  ending sequences are literal strings as shown,
+       but the letters can be in either  case.  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 original
+       UTF-8 rules of RFC 2279. This allows for  values  in  the  range  0  to
+       0x7FFFFFFF.  Note  that not all of those are valid Unicode code points,
+       or indeed valid UTF-8 characters according to the later  rules  in  RFC
+       3629.
+
+
+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
+
+       Note  that unset capturing substrings that are not followed by one that
+       is set are not returned by pcre_exec(), and are not shown by  pcretest.
+       In  the following example, there are two capturing substrings, but when
+       the first data line is matched, the  second,  unset  substring  is  not
+       shown.  An "internal" unset substring is shown as "<unset>", as for the
+       second data line.
+
+           re> /(a)|(b)/
+         data> a
+          0: a
+          1: a
+         data> b
+          0: b
+          1: <unset>
+          2: b
+
+       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: 12 April 2008
+       Copyright (c) 1997-2008 University of Cambridge.