URLの ％表記

googleで検索した結果のURLをコピペしようとすると%がついた文字列になっている。その文字列でURLに指定するとうまく接続してくれない。
PDFのファイル名などでなければ、接続した先のURLをコピペすればいい。ファイルだと、PDF Readerが立ち上がってしまったURLを示さない。

URLエンコードというらしい。

RFC3986
https://tools.ietf.org/html/rfc3986

#参考資料(reference)

URLエンコード対応表メモ
https://qiita.com/i47_rozary/items/4f7c3ac08ee0836c1ca2

URLのクエリーパラメータでエスケープしなくていい文字はどれか？
https://qiita.com/aosho235/items/0581fc82f8ce2c5ac055

URLエンコード/デコード(perl)
https://qiita.com/wittyfool@github/items/407900819b5ed46b9631


シェルスクリプトでシンプルにurlエンコードする話
https://qiita.com/ik-fib/items/cc983ca34600c2d633d5

URLエンコードされてない部分をURLエンコードする（RFC3986準拠）
https://qiita.com/hiraiva/items/1b2d6d27d13dab0a1a42


#RFC3986参照(reference)
## Normative References

   [ASCII]    American National Standards Institute, "Coded Character
              Set -- 7-bit American Standard Code for Information
              Interchange", ANSI X3.4, 1986.

   [RFC2234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", RFC 2234, November 1997.

   [STD63]    Yergeau, F., "UTF-8, a transformation format of
              ISO 10646", STD 63, RFC 3629, November 2003.

   [UCS]      International Organization for Standardization,
              "Information Technology - Universal Multiple-Octet Coded
              Character Set (UCS)", ISO/IEC 10646:2003, December 2003.

##  Informative References

   [BCP19]    Freed, N. and J. Postel, "IANA Charset Registration
              Procedures", BCP 19, RFC 2978, October 2000.

   [BCP35]    Petke, R. and I. King, "Registration Procedures for URL
              Scheme Names", BCP 35, RFC 2717, November 1999.

   [RFC0952]  Harrenstien, K., Stahl, M., and E. Feinler, "DoD Internet
              host table specification", RFC 952, October 1985.

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, November 1987.

   [RFC1123]  Braden, R., "Requirements for Internet Hosts - Application
              and Support", STD 3, RFC 1123, October 1989.

   [RFC1535]  Gavron, E., "A Security Problem and Proposed Correction
              With Widely Deployed DNS Software", RFC 1535,
              October 1993.

   [RFC1630]  Berners-Lee, T., "Universal Resource Identifiers in WWW: A
              Unifying Syntax for the Expression of Names and Addresses
              of Objects on the Network as used in the World-Wide Web",
              RFC 1630, June 1994.

   [RFC1736]  Kunze, J., "Functional Recommendations for Internet
              Resource Locators", RFC 1736, February 1995.

   [RFC1737]  Sollins, K. and L. Masinter, "Functional Requirements for
              Uniform Resource Names", RFC 1737, December 1994.

   [RFC1738]  Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform
              Resource Locators (URL)", RFC 1738, December 1994.

   [RFC1808]  Fielding, R., "Relative Uniform Resource Locators",
              RFC 1808, June 1995.



   [RFC2046]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part Two: Media Types", RFC 2046,
              November 1996.

   [RFC2141]  Moats, R., "URN Syntax", RFC 2141, May 1997.

   [RFC2396]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifiers (URI): Generic Syntax", RFC 2396,
              August 1998.

   [RFC2518]  Goland, Y., Whitehead, E., Faizi, A., Carter, S., and D.
              Jensen, "HTTP Extensions for Distributed Authoring --
              WEBDAV", RFC 2518, February 1999.

   [RFC2557]  Palme, J., Hopmann, A., and N. Shelness, "MIME
              Encapsulation of Aggregate Documents, such as HTML
              (MHTML)", RFC 2557, March 1999.

   [RFC2718]  Masinter, L., Alvestrand, H., Zigmond, D., and R. Petke,
              "Guidelines for new URL Schemes", RFC 2718, November 1999.

   [RFC2732]  Hinden, R., Carpenter, B., and L. Masinter, "Format for
              Literal IPv6 Addresses in URL's", RFC 2732, December 1999.

   [RFC3305]  Mealling, M. and R. Denenberg, "Report from the Joint
              W3C/IETF URI Planning Interest Group: Uniform Resource
              Identifiers (URIs), URLs, and Uniform Resource Names
              (URNs): Clarifications and Recommendations", RFC 3305,
              August 2002.

   [RFC3490]  Faltstrom, P., Hoffman, P., and A. Costello,
              "Internationalizing Domain Names in Applications (IDNA)",
              RFC 3490, March 2003.

   [RFC3513]  Hinden, R. and S. Deering, "Internet Protocol Version 6
              (IPv6) Addressing Architecture", RFC 3513, April 2003.

   [Siedzik]  Siedzik, R., "Semantic Attacks: What's in a URL?",
              April 2001, <http://www.giac.org/practical/gsec/
              Richard_Siedzik_GSEC.pdf>.

# 文書履歴(document history)
ver. 0.01 初稿 20190313 早朝
ver. 0.02 みだし追記　20190313 朝
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