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Oniguruma is a modern and flexible regular expressions library. It encompasses features from different regular expression implementations that traditionally exist in different languages.

Character encoding can be specified per regular expression object.

Supported character encodings:

ASCII, UTF-8, UTF-16BE, UTF-16LE, UTF-32BE, UTF-32LE, EUC-JP, EUC-TW, EUC-KR, EUC-CN, Shift_JIS, Big5, GB18030, KOI8-R, CP1251, ISO-8859-1, ISO-8859-2, ISO-8859-3, ISO-8859-4, ISO-8859-5, ISO-8859-6, ISO-8859-7, ISO-8859-8, ISO-8859-9, ISO-8859-10, ISO-8859-11, ISO-8859-13, ISO-8859-14, ISO-8859-15, ISO-8859-16

  • GB18030: contributed by KUBO Takehiro
  • CP1251: contributed by Byte
  • doc/ contributed by seanofw

Version 6.9.6

  • When using configure script, if you have the POSIX API enabled in an earlier version (disabled by default in 6.9.5) and you need application binary compatibility with the POSIX API, specify "--enable-binary-compatible-posix-api=yes" instead of "--enable-posix-api=yes". Starting in 6.9.6, "--enable-posix-api=yes" only supports source-level compatibility for 6.9.5 and earlier about POSIX API. (Issue #210)

  • NEW: configure option --enable-binary-compatible-posix-api=[yes/no]

  • NEW API: Limiting the maximum number of calls of subexp-call


  • Fixed behavior of ONIG_OPTION_NOTBOL / NOTEOL

  • Fixed many problems found by OSS-Fuzz

  • Fixed many problems found by Coverity

  • Fixed CVE-2020-26159 (This turned out not to be a problem later. #221)

  • Under cygwin and mingw, generate and install the libonig.def file (Issue #220)

Version 6.9.5 revised 1

  • Fixed Issue #192

Version 6.9.5

  • POSIX API disabled by default for Unix (* Enabled by: configure --enable-posix-api=yes)
  • Update Unicode version 13.0.0
  • NEW: Code point sequence notation \x{HHHH HHHH ...}, \o{OOOO OOOO ...}
  • NEW API: retry limit in search functions
  • NEW API: maximum nesting level of subexp call
  • Fixed behavior of isolated options in Perl and Java syntaxes. /...(?i).../

Version 6.9.4

  • NEW API: RegSet (set of regexes)
  • Fixed CVE-2019-19012
  • Fixed CVE-2019-19203 (Does not affect UTF-8, UTF-16 and UTF-32 encodings)
  • Fixed CVE-2019-19204 (Affects only PosixBasic, Emacs and Grep syntaxes)
  • Fixed CVE-2019-19246
  • Fixed some problems (found by libFuzzer test)

Version 6.9.3 (security fix release)

  • Fixed CVE-2019-13224
  • Fixed CVE-2019-13225
  • Fixed CVE-2019-16163
  • Fixed many problems (found by libFuzzer test)

Version 6.9.2 (Reiwa)

  • add doc/
  • Direct threaded code (for GCC and Clang)
  • Update Unicode version 12.1.0
  • NEW: Unicode Text Segment mode option (?y{g}) (?y{w}) (*original)

Version 6.9.1

  • Speed improvement (* especially UTF-8)

Version 6.9.0

  • Update Unicode version 11.0.0
  • NEW: add Emoji properties

Version 6.8.2

  • Fix: #80 UChar in header causes issue
  • NEW API: onig_set_callout_user_data_of_match_param() (* omission in 6.8.0)
  • add doc/CALLOUTS.API and doc/CALLOUTS.API.ja

Version 6.8.1

  • Update shared library version to 5.0.0 for API incompatible changes from 6.7.1

Version 6.8.0

  • Retry-limit-in-match function enabled by default
  • NEW: configure option --enable-posix-api=no (* enabled by default)
  • NEW API: onig_search_with_param(), onig_match_with_param()
  • NEW: Callouts of contents (?{...contents...}) (?{...}[tag][X<>]) (?{{...}})
  • NEW: Callouts of name (*name) (*name[tag]{args...})
  • NEW: Builtin callouts (*FAIL) (*MISMATCH) (*ERROR{n}) (*COUNT) (*MAX{n}) etc..
  • Examples of Callouts program: callout.c, count.c, echo.c

Version 6.7.1

  • NEW: Mechanism of retry-limit-in-match (* disabled by default)

Version 6.7.0

  • NEW: hexadecimal codepoint \uHHHH
  • Disabled \N and \O on ONIG_SYNTAX_RUBY
  • Reduced size of object file

Version 6.6.0

  • NEW: ASCII only mode options for character type/property (?WDSP)
  • NEW: Extended Grapheme Cluster boundary \y, \Y
  • NEW: Extended Grapheme Cluster \X
  • Range-clear (Absent-clear) operator restores previous range in retractions.

Version 6.5.0

  • NEW: \K (keep)
  • NEW: \R (general newline) \N (no newline)
  • NEW: \O (true anychar)
  • NEW: if-then-else (?(...)...|...)
  • NEW: Backreference validity checker (?(xxx)) (*original)
  • NEW: Absent repeater (?~absent) [is equal to (?~|(?:absent)|\O*)]
  • NEW: Absent expression (?~|absent|expr) (*original)
  • NEW: Absent stopper (?~|absent) (*original)


BSD license.


Case 1: Linux distribution packages

  • Fedora: dnf install oniguruma
  • RHEL/CentOS: yum install oniguruma
  • Debian/Ubuntu: apt install libonig5
  • Arch: pacman -S oniguruma
  • openSUSE: zypper install oniguruma

Case 2: Manual compilation on Linux, Unix, and Cygwin platform

  1. autoreconf -vfi (* case: configure script is not found.)

  2. ./configure

  3. make

  4. make install

  • uninstall

    make uninstall

  • configuration check

    onig-config --cflags onig-config --libs onig-config --prefix onig-config --exec-prefix

Case 3: Windows 64/32bit platform (Visual Studio)

Execute make_win.bat

  onig_s.lib:  static link library
  onig.dll:    dynamic link library
  • test (ASCII/Shift_JIS)

    1. cd src
    2. copy ..\windows\testc.c .
    3. nmake -f ctest

(I have checked by Visual Studio Community 2015)

Alternatively, you can build and install oniguruma using vcpkg dependency manager:

  1. git clone
  2. cd vcpkg
  3. ./bootstrap-vcpkg.bat
  4. ./vcpkg integrate install
  5. ./vcpkg install oniguruma

The oniguruma port in vcpkg is kept up to date by microsoft team members and community contributors. If the version is out of date, please create an issue or pull request on the vcpkg repository.

Regular Expressions

See doc/RE or doc/RE.ja for Japanese.


Include oniguruma.h in your program. (Oniguruma API) See doc/API for Oniguruma API.

If you want to disable UChar type (== unsigned char) definition in oniguruma.h, define ONIG_ESCAPE_UCHAR_COLLISION and then include oniguruma.h.

If you want to disable regex_t type definition in oniguruma.h, define ONIG_ESCAPE_REGEX_T_COLLISION and then include oniguruma.h.

Example of the compiling/linking command line in Unix or Cygwin, (prefix == /usr/local case)

cc sample.c -L/usr/local/lib -lonig

If you want to use static link library(onig_s.lib) in Win32, add option -DONIG_EXTERN=extern to C compiler.

Sample Programs

File Description
sample/callout.c example of callouts
sample/count.c example of built-in callout *COUNT
sample/echo.c example of user defined callouts of name
sample/encode.c example of some encodings
sample/listcap.c example of the capture history
sample/names.c example of the named group callback
sample/posix.c POSIX API sample
sample/regset.c example of using RegSet API
sample/scan.c example of using onig_scan()
sample/simple.c example of the minimum (Oniguruma API)
sample/sql.c example of the variable meta characters
sample/user_property.c example of user defined Unicode property

Test Programs

File Description
sample/syntax.c Perl, Java and ASIS syntax test.
sample/crnl.c --enable-crnl-as-line-terminator test

Source Files

File Description
oniguruma.h Oniguruma API header file (public) configuration check program template
regenc.h character encodings framework header file
regint.h internal definitions
regparse.h internal definitions for regparse.c and regcomp.c
regcomp.c compiling and optimization functions
regenc.c character encodings framework
regerror.c error message function
regext.c extended API functions (deluxe version API)
regexec.c search and match functions
regparse.c parsing functions.
regsyntax.c pattern syntax functions and built-in syntax definitions
regtrav.c capture history tree data traverse functions
regversion.c version info function
st.h hash table functions header file
st.c hash table functions
oniggnu.h GNU regex API header file (public)
reggnu.c GNU regex API functions
onigposix.h POSIX API header file (public)
regposerr.c POSIX error message function
regposix.c POSIX API functions
mktable.c character type table generator
ascii.c ASCII encoding
euc_jp.c EUC-JP encoding
euc_tw.c EUC-TW encoding
euc_kr.c EUC-KR, EUC-CN encoding
sjis.c Shift_JIS encoding
big5.c Big5 encoding
gb18030.c GB18030 encoding
koi8.c KOI8 encoding
koi8_r.c KOI8-R encoding
cp1251.c CP1251 encoding
iso8859_1.c ISO-8859-1 (Latin-1)
iso8859_2.c ISO-8859-2 (Latin-2)
iso8859_3.c ISO-8859-3 (Latin-3)
iso8859_4.c ISO-8859-4 (Latin-4)
iso8859_5.c ISO-8859-5 (Cyrillic)
iso8859_6.c ISO-8859-6 (Arabic)
iso8859_7.c ISO-8859-7 (Greek)
iso8859_8.c ISO-8859-8 (Hebrew)
iso8859_9.c ISO-8859-9 (Latin-5 or Turkish)
iso8859_10.c ISO-8859-10 (Latin-6 or Nordic)
iso8859_11.c ISO-8859-11 (Thai)
iso8859_13.c ISO-8859-13 (Latin-7 or Baltic Rim)
iso8859_14.c ISO-8859-14 (Latin-8 or Celtic)
iso8859_15.c ISO-8859-15 (Latin-9 or West European with Euro)
iso8859_16.c ISO-8859-16 (Latin-10)
utf8.c UTF-8 encoding
utf16_be.c UTF-16BE encoding
utf16_le.c UTF-16LE encoding
utf32_be.c UTF-32BE encoding
utf32_le.c UTF-32LE encoding
unicode.c common codes of Unicode encoding
unicode_fold_data.c Unicode folding data
windows/testc.c Test program for Windows (VC++)

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