nkf - Man Page

Network Kanji Filter

Examples (TL;DR)

Convert to UTF-8 encoding: nkf -w path/to/file.txt
Convert to SHIFT_JIS encoding: nkf -s path/to/file.txt
Convert to UTF-8 encoding and overwrite the file: nkf -w --overwrite path/to/file.txt
Use LF as the new line code and overwrite (UNIX type): nkf -d --overwrite path/to/file.txt
Use CRLF as the new line code and overwrite (windows type): nkf -c --overwrite path/to/file.txt
Decrypt mime file and overwrite: nkf -m --overwrite path/to/file.txt

Synopsis

nkf [-butjnesliohrTVvwWJESZxXFfmMBOcdILg] [file ...]

Nkf is a yet another kanji code converter among networks, hosts and terminals. It converts input kanji code to designated kanji code such as ISO-2022-JP, Shift_JIS, EUC-JP, UTF-8, UTF-16 or UTF-32.

One of the most unique faculty of nkf is the guess of the input kanji encodings. It currently recognizes ISO-2022-JP, Shift_JIS, EUC-JP, UTF-8, UTF-16 and UTF-32. So users needn't set the input kanji code explicitly.

By default, X0201 kana is converted into X0208 kana. For X0201 kana, SO/SI, SSO and ESC-(-I methods are supported. For automatic code detection, nkf assumes no X0201 kana in Shift_JIS. To accept X0201 in Shift_JIS, use -X, -x or -S.

multiple options are specifed as seprate strings, such as

  print nkf('--ic=UTF8-MAC', '-w', $string), "\n";

except the last arguments.

Options

-J -S -E -W -W16 -W32 -j -s -e -w -w16 -w32

Specify input and output encodings. Upper case is input. cf. --ic and --oc.

-J: ISO-2022-JP (JIS code).
-S: Shift_JIS and JIS X 0201 kana. EUC-JP is recognized as X0201 kana. Without -x flag, JIS X 0201 Katakana (a.k.a.halfwidth kana) is converted into JIS X 0208. If you use Windows, see Windows-31J (CP932).
-E: EUC-JP.
-W: UTF-8N.
-W16[BL][0]: UTF-16. B or L gives whether Big Endian or Little Endian. 0 gives whther put BOM or not.
-W32[BL][0]: UTF-32. B or L gives whether Big Endian or Little Endian. 0 gives whther put BOM or not.

-b -u

Output is buffered (DEFAULT), Output is unbuffered.

-t

No conversion.

-i[@B]

Specify the escape sequence for JIS X 0208.

-i@: Use ESC ( @. (JIS X 0208-1978)
-iB: Use ESC ( B. (JIS X 0208-1983/1990 DEFAULT)

-o[BJ]

Specify the escape sequence for US-ASCII/JIS X 0201 Roman. (DEFAULT B)

-r

{de/en}crypt ROT13/47

-h[123] --hiragana --katakana --katakana-hiragana

-h1 --hiragana: Katakana to Hiragana conversion.
-h2 --katakana: Hiragana to Katakana conversion.
-h3 --katakana-hiragana: Katakana to Hiragana and Hiragana to Katakana conversion.

-T

Text mode output (MS-DOS)

-f[m [- n]]

Folding on m length with n margin in a line. Without this option, fold length is 60 and fold margin is 10.

-F

New line preserving line folding.

-Z[0-3]

Convert X0208 alphabet (Fullwidth Alphabets) to ASCII.

-Z -Z0: Convert X0208 alphabet to ASCII.
-Z1: Convert X0208 kankaku to single ASCII space.
-Z2: Convert X0208 kankaku to double ASCII spaces.
-Z3: Replacing fullwidth >, <, ", & into '>', '<', '"', '&' as in HTML.

-X -x

With -X or without this option, X0201 is converted into X0208 Kana. With -x, try to preserve X0208 kana and do not convert X0201 kana to X0208. In JIS output, ESC-(-I is used. In EUC output, SS2 is used.

-B[0-2]

Assume broken JIS-Kanji input, which lost ESC. Useful when your site is using old B-News Nihongo patch.

-B1: allows any chars after ESC-( or ESC-$.
-B2: force ASCII after NL.

-I

Replacing non iso-2022-jp char into a geta character (substitute character in Japanese).

-m[BQN0]

MIME ISO-2022-JP/ISO8859-1 decode. (DEFAULT) To see ISO8859-1 (Latin-1) -l is necessary.

-mB: Decode MIME base64 encoded stream. Remove header or other part before conversion.
-mQ: Decode MIME quoted stream. '_' in quoted stream is converted to space.
-mN: Non-strict decoding. It allows line break in the middle of the base64 encoding.
-m0: No MIME decode.

-M

MIME encode. Header style. All ASCII code and control characters are intact.

-MB: MIME encode Base64 stream. Kanji conversion is performed before encoding, so this cannot be used as a picture encoder.
-MQ: Perform quoted encoding.

-l

Input and output code is ISO8859-1 (Latin-1) and ISO-2022-JP. -s, -e and -x are not compatible with this option.

-L[uwm] -d -c

Convert line breaks.

-Lu -d

unix (LF)

-Lw -c

windows (CRLF)

-Lm

mac (CR)

Without this option, nkf doesn't convert line breaks.

--fj --unix --mac --msdos --windows

Convert for these systems.

--jis --euc --sjis --mime --base64

Convert to named code.

--jis-input --euc-input --sjis-input --mime-input --base64-input

Assume input system

--ic=input codeset --oc=output codeset

Set the input or output codeset. NKF supports following codesets and those codeset names are case insensitive.

ISO-2022-JP: a.k.a. RFC1468, 7bit JIS, JUNET
EUC-JP (eucJP-nkf): a.k.a. AT&T JIS, Japanese EUC, UJIS
eucJP-ascii
eucJP-ms
CP51932: Microsoft Version of EUC-JP.
Shift_JIS: a.k.a. SJIS, MS_Kanji
Windows-31J: a.k.a. CP932
UTF-8: same as UTF-8N
UTF-8N: UTF-8 without BOM
UTF-8-BOM: UTF-8 with BOM
UTF8-MAC (input only): decomposed UTF-8
UTF-16: same as UTF-16BE
UTF-16BE: UTF-16 Big Endian without BOM
UTF-16BE-BOM: UTF-16 Big Endian with BOM
UTF-16LE: UTF-16 Little Endian without BOM
UTF-16LE-BOM: UTF-16 Little Endian with BOM
UTF-32: same as UTF-32BE
UTF-32BE: UTF-32 Big Endian without BOM
UTF-32BE-BOM: UTF-32 Big Endian with BOM
UTF-32LE: UTF-32 Little Endian without BOM
UTF-32LE-BOM: UTF-32 Little Endian with BOM

--fb-{skip, html, xml, perl, java, subchar}

Specify the way that nkf handles unassigned characters. Without this option, --fb-skip is assumed.

--prefix=escape charactertarget character..

When nkf converts to Shift_JIS, nkf adds a specified escape character to specified 2nd byte of Shift_JIS characters. 1st byte of argument is the escape character and following bytes are target characters.

--no-cp932ext

Handle the characters extended in CP932 as unassigned characters.

--no-best-fit-chars

When Unicode to Encoded byte conversion, don't convert characters which is not round trip safe. When Unicode to Unicode conversion, with this and -x option, nkf can be used as UTF converter. (In other words, without this and -x option, nkf doesn't save some characters)

When nkf converts strings that related to path, you should use this opion.

--cap-input