# URI - man - phpMan

[URI(3pm)](https://www.chedong.com/phpMan.php/man/URI/3pm/markdown)                         User Contributed Perl Documentation                        [URI(3pm)](https://www.chedong.com/phpMan.php/man/URI/3pm/markdown)



## NAME
       URI - Uniform Resource Identifiers (absolute and relative)

## SYNOPSIS
        use URI ();

        $u1 = URI->new("<http://www.example.com>");
        $u2 = URI->new("foo", "http");
        $u3 = $u2->abs($u1);
        $u4 = $u3->clone;
        $u5 = URI->new("<HTTP://WWW.example.com:80>")->canonical;

        $str = $u->as_string;
        $str = "$u";

        $scheme = $u->scheme;
        $opaque = $u->opaque;
        $path   = $u->path;
        $frag   = $u->fragment;

        $u->scheme("ftp");
        $u->host("ftp.example.com");
        $u->path("cpan/");

## DESCRIPTION
       This module implements the "URI" class.  Objects of this class represent "Uniform Resource
       Identifier references" as specified in RFC 2396 (and updated by RFC 2732).

       A Uniform Resource Identifier is a compact string of characters that identifies an abstract
       or physical resource.  A Uniform Resource Identifier can be further classified as either a
       Uniform Resource Locator (URL) or a Uniform Resource Name (URN).  The distinction between URL
       and URN does not matter to the "URI" class interface. A "URI-reference" is a URI that may
       have additional information attached in the form of a fragment identifier.

       An absolute URI reference consists of three parts:  a _scheme_, a _scheme-specific_ _part_ and a
       _fragment_ identifier.  A subset of URI references share a common syntax for hierarchical
       namespaces.  For these, the scheme-specific part is further broken down into _authority_, _path_
       and _query_ components.  These URIs can also take the form of relative URI references, where
       the scheme (and usually also the authority) component is missing, but implied by the context
       of the URI reference.  The three forms of URI reference syntax are summarized as follows:

         <scheme>:<scheme-specific-part>#<fragment>
         <scheme>://<authority><path>?<query>#<fragment>
         <path>?<query>#<fragment>

       The components into which a URI reference can be divided depend on the _scheme_.  The "URI"
       class provides methods to get and set the individual components.  The methods available for a
       specific "URI" object depend on the scheme.

## CONSTRUCTORS
       The following methods construct new "URI" objects:

       $uri = URI->new( $str )
       $uri = URI->new( $str, $scheme )
           Constructs a new URI object.  The string representation of a URI is given as argument,
           together with an optional scheme specification.  Common URI wrappers like "" and <>, as
           well as leading and trailing white space, are automatically removed from the $str
           argument before it is processed further.

           The constructor determines the scheme, maps this to an appropriate URI subclass,
           constructs a new object of that class and returns it.

           If the scheme isn't one of those that URI recognizes, you still get an URI object back
           that you can access the generic methods on.  The "$uri->has_recognized_scheme" method can
           be used to test for this.

           The $scheme argument is only used when $str is a relative URI.  It can be either a simple
           string that denotes the scheme, a string containing an absolute URI reference, or an
           absolute "URI" object.  If no $scheme is specified for a relative URI $str, then $str is
           simply treated as a generic URI (no scheme-specific methods available).

           The set of characters available for building URI references is restricted (see
           [URI::Escape](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3AEscape/markdown)).  Characters outside this set are automatically escaped by the URI
           constructor.

       $uri = URI->new_abs( $str, $base_uri )
           Constructs a new absolute URI object.  The $str argument can denote a relative or
           absolute URI.  If relative, then it is absolutized using $base_uri as base. The $base_uri
           must be an absolute URI.

       $uri = [URI::file](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3Afile/markdown)->new( $filename )
       $uri = [URI::file](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3Afile/markdown)->new( $filename, $os )
           Constructs a new _file_ URI from a file name.  See [URI::file](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3Afile/markdown).

       $uri = [URI::file](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3Afile/markdown)->new_abs( $filename )
       $uri = [URI::file](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3Afile/markdown)->new_abs( $filename, $os )
           Constructs a new absolute _file_ URI from a file name.  See [URI::file](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3Afile/markdown).

       $uri = [URI::file](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3Afile/markdown)->cwd
           Returns the current working directory as a _file_ URI.  See [URI::file](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3Afile/markdown).

       $uri->clone
           Returns a copy of the $uri.

## COMMON METHODS
       The methods described in this section are available for all "URI" objects.

       Methods that give access to components of a URI always return the old value of the component.
       The value returned is "undef" if the component was not present.  There is generally a
       difference between a component that is empty (represented as "") and a component that is
       missing (represented as "undef").  If an accessor method is given an argument, it updates the
       corresponding component in addition to returning the old value of the component.  Passing an
       undefined argument removes the component (if possible).  The description of each accessor
       method indicates whether the component is passed as an escaped (percent-encoded) or an
       unescaped string.  A component that can be further divided into sub-parts are usually passed
       escaped, as unescaping might change its semantics.

       The common methods available for all URI are:

       $uri->scheme
       $uri->scheme( $new_scheme )
           Sets and returns the scheme part of the $uri.  If the $uri is relative, then $uri->scheme
           returns "undef".  If called with an argument, it updates the scheme of $uri, possibly
           changing the class of $uri, and returns the old scheme value.  The method croaks if the
           new scheme name is illegal; a scheme name must begin with a letter and must consist of
           only US-ASCII letters, numbers, and a few special marks: ".", "+", "-".  This restriction
           effectively means that the scheme must be passed unescaped.  Passing an undefined
           argument to the scheme method makes the URI relative (if possible).

           Letter case does not matter for scheme names.  The string returned by $uri->scheme is
           always lowercase.  If you want the scheme just as it was written in the URI in its
           original case, you can use the $uri->_scheme method instead.

       $uri->has_recognized_scheme
           Returns TRUE if the URI scheme is one that URI recognizes.

           It will also be TRUE for relative URLs where a recognized scheme was provided to the
           constructor, even if "$uri->scheme" returns "undef" for these.

       $uri->opaque
       $uri->opaque( $new_opaque )
           Sets and returns the scheme-specific part of the $uri (everything between the scheme and
           the fragment) as an escaped string.

       $uri->path
       $uri->path( $new_path )
           Sets and returns the same value as $uri->opaque unless the URI supports the generic
           syntax for hierarchical namespaces.  In that case the generic method is overridden to set
           and return the part of the URI between the _host_ _name_ and the _fragment_.

       $uri->fragment
       $uri->fragment( $new_frag )
           Returns the fragment identifier of a URI reference as an escaped string.

       $uri->as_string
           Returns a URI object to a plain ASCII string.  URI objects are also converted to plain
           strings automatically by overloading.  This means that $uri objects can be used as plain
           strings in most Perl constructs.

       $uri->as_iri
           Returns a Unicode string representing the URI.  Escaped UTF-8 sequences representing non-
           ASCII characters are turned into their corresponding Unicode code point.

       $uri->canonical
           Returns a normalized version of the URI.  The rules for normalization are scheme-
           dependent.  They usually involve lowercasing the scheme and Internet host name
           components, removing the explicit port specification if it matches the default port,
           uppercasing all escape sequences, and unescaping octets that can be better represented as
           plain characters.

           For efficiency reasons, if the $uri is already in normalized form, then a reference to it
           is returned instead of a copy.

       $uri->eq( $other_uri )
       [URI::eq](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3Aeq/markdown)( $first_uri, $other_uri )
           Tests whether two URI references are equal.  URI references that normalize to the same
           string are considered equal.  The method can also be used as a plain function which can
           also test two string arguments.

           If you need to test whether two "URI" object references denote the same object, use the
           '==' operator.

       $uri->abs( $base_uri )
           Returns an absolute URI reference.  If $uri is already absolute, then a reference to it
           is simply returned.  If the $uri is relative, then a new absolute URI is constructed by
           combining the $uri and the $base_uri, and returned.

       $uri->rel( $base_uri )
           Returns a relative URI reference if it is possible to make one that denotes the same
           resource relative to $base_uri.  If not, then $uri is simply returned.

       $uri->secure
           Returns a TRUE value if the URI is considered to point to a resource on a secure channel,
           such as an SSL or TLS encrypted one.

## GENERIC METHODS
       The following methods are available to schemes that use the common/generic syntax for
       hierarchical namespaces.  The descriptions of schemes below indicate which these are.
       Unrecognized schemes are assumed to support the generic syntax, and therefore the following
       methods:

       $uri->authority
       $uri->authority( $new_authority )
           Sets and returns the escaped authority component of the $uri.

       $uri->path
       $uri->path( $new_path )
           Sets and returns the escaped path component of the $uri (the part between the host name
           and the query or fragment).  The path can never be undefined, but it can be the empty
           string.

       $uri->path_query
       $uri->path_query( $new_path_query )
           Sets and returns the escaped path and query components as a single entity.  The path and
           the query are separated by a "?" character, but the query can itself contain "?".

       $uri->path_segments
       $uri->path_segments( $segment, ... )
           Sets and returns the path.  In a scalar context, it returns the same value as $uri->path.
           In a list context, it returns the unescaped path segments that make up the path.  Path
           segments that have parameters are returned as an anonymous array.  The first element is
           the unescaped path segment proper;  subsequent elements are escaped parameter strings.
           Such an anonymous array uses overloading so it can be treated as a string too, but this
           string does not include the parameters.

           Note that absolute paths have the empty string as their first _path_segment_, i.e. the _path_
           "/foo/bar" have 3 _path_segments_; "", "foo" and "bar".

       $uri->query
       $uri->query( $new_query )
           Sets and returns the escaped query component of the $uri.

       $uri->query_form
       $uri->query_form( $key1 => $val1, $key2 => $val2, ... )
       $uri->query_form( $key1 => $val1, $key2 => $val2, ..., $delim )
       $uri->query_form( \@key_value_pairs )
       $uri->query_form( \@key_value_pairs, $delim )
       $uri->query_form( \%hash )
       $uri->query_form( \%hash, $delim )
           Sets and returns query components that use the _application/x-www-form-urlencoded_ format.
           Key/value pairs are separated by "&", and the key is separated from the value by a "="
           character.

           The form can be set either by passing separate key/value pairs, or via an array or hash
           reference.  Passing an empty array or an empty hash removes the query component, whereas
           passing no arguments at all leaves the component unchanged.  The order of keys is
           undefined if a hash reference is passed.  The old value is always returned as a list of
           separate key/value pairs.  Assigning this list to a hash is unwise as the keys returned
           might repeat.

           The values passed when setting the form can be plain strings or references to arrays of
           strings.  Passing an array of values has the same effect as passing the key repeatedly
           with one value at a time.  All the following statements have the same effect:

               $uri->query_form(foo => 1, foo => 2);
               $uri->query_form(foo => [1, 2]);
               $uri->query_form([ foo => 1, foo => 2 ]);
               $uri->query_form([ foo => [1, 2] ]);
               $uri->query_form({ foo => [1, 2] });

           The $delim parameter can be passed as ";" to force the key/value pairs to be delimited by
           ";" instead of "&" in the query string.  This practice is often recommended for URLs
           embedded in HTML or XML documents as this avoids the trouble of escaping the "&"
           character.  You might also set the $[URI::DEFAULT_QUERY_FORM_DELIMITER](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3ADEFAULTQUERYFORMDELIMITER/markdown) variable to ";" for
           the same global effect.

           The "[URI::QueryParam](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3AQueryParam/markdown)" module can be loaded to add further methods to manipulate the form
           of a URI.  See [URI::QueryParam](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3AQueryParam/markdown) for details.

       $uri->query_keywords
       $uri->query_keywords( $keywords, ... )
       $uri->query_keywords( \@keywords )
           Sets and returns query components that use the keywords separated by "+" format.

           The keywords can be set either by passing separate keywords directly or by passing a
           reference to an array of keywords.  Passing an empty array removes the query component,
           whereas passing no arguments at all leaves the component unchanged.  The old value is
           always returned as a list of separate words.

## SERVER METHODS
       For schemes where the _authority_ component denotes an Internet host, the following methods are
       available in addition to the generic methods.

       $uri->userinfo
       $uri->userinfo( $new_userinfo )
           Sets and returns the escaped userinfo part of the authority component.

           For some schemes this is a user name and a password separated by a colon.  This practice
           is not recommended. Embedding passwords in clear text (such as URI) has proven to be a
           security risk in almost every case where it has been used.

       $uri->host
       $uri->host( $new_host )
           Sets and returns the unescaped hostname.

           If the $new_host string ends with a colon and a number, then this number also sets the
           port.

           For IPv6 addresses the brackets around the raw address is removed in the return value
           from $uri->host.  When setting the host attribute to an IPv6 address you can use a raw
           address or one enclosed in brackets.  The address needs to be enclosed in brackets if you
           want to pass in a new port value as well.

       $uri->ihost
           Returns the host in Unicode form.  Any IDNA A-labels are turned into U-labels.

       $uri->port
       $uri->port( $new_port )
           Sets and returns the port.  The port is a simple integer that should be greater than 0.

           If a port is not specified explicitly in the URI, then the URI scheme's default port is
           returned. If you don't want the default port substituted, then you can use the
           $uri->_port method instead.

       $uri->host_port
       $uri->host_port( $new_host_port )
           Sets and returns the host and port as a single unit.  The returned value includes a port,
           even if it matches the default port.  The host part and the port part are separated by a
           colon: ":".

           For IPv6 addresses the bracketing is preserved; thus URI->new("http://[::1]/")->host_port
           returns "[::1]:80".  Contrast this with $uri->host which will remove the brackets.

       $uri->default_port
           Returns the default port of the URI scheme to which $uri belongs.  For _http_ this is the
           number 80, for _ftp_ this is the number 21, etc.  The default port for a scheme can not be
           changed.

## SCHEME-SPECIFIC SUPPORT
       Scheme-specific support is provided for the following URI schemes.  For "URI" objects that do
       not belong to one of these, you can only use the common and generic methods.

       **data**:
           The _data_ URI scheme is specified in RFC 2397.  It allows inclusion of small data items as
           "immediate" data, as if it had been included externally.

           "URI" objects belonging to the data scheme support the common methods and two new methods
           to access their scheme-specific components: $uri->media_type and $uri->data.  See
           [URI::data](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3Adata/markdown) for details.

       **file**:
           An old specification of the _file_ URI scheme is found in RFC 1738.  A new RFC 2396 based
           specification in not available yet, but file URI references are in common use.

           "URI" objects belonging to the file scheme support the common and generic methods.  In
           addition, they provide two methods for mapping file URIs back to local file names;
           $uri->file and $uri->dir.  See [URI::file](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3Afile/markdown) for details.

       **ftp**:
           An old specification of the _ftp_ URI scheme is found in RFC 1738.  A new RFC 2396 based
           specification in not available yet, but ftp URI references are in common use.

           "URI" objects belonging to the ftp scheme support the common, generic and server methods.
           In addition, they provide two methods for accessing the userinfo sub-components:
           $uri->user and $uri->password.

       **gopher**:
           The _gopher_ URI scheme is specified in <draft-murali-url-gopher-1996-12-04> and will
           hopefully be available as a RFC 2396 based specification.

           "URI" objects belonging to the gopher scheme support the common, generic and server
           methods. In addition, they support some methods for accessing gopher-specific path
           components: $uri->gopher_type, $uri->selector, $uri->search, $uri->string.

       **http**:
           The _http_ URI scheme is specified in RFC 2616.  The scheme is used to reference resources
           hosted by HTTP servers.

           "URI" objects belonging to the http scheme support the common, generic and server
           methods.

       **https**:
           The _https_ URI scheme is a Netscape invention which is commonly implemented.  The scheme
           is used to reference HTTP servers through SSL connections.  Its syntax is the same as
           http, but the default port is different.

       **ldap**:
           The _ldap_ URI scheme is specified in RFC 2255.  LDAP is the Lightweight Directory Access
           Protocol.  An ldap URI describes an LDAP search operation to perform to retrieve
           information from an LDAP directory.

           "URI" objects belonging to the ldap scheme support the common, generic and server methods
           as well as ldap-specific methods: $uri->dn, $uri->attributes, $uri->scope, $uri->filter,
           $uri->extensions.  See [URI::ldap](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3Aldap/markdown) for details.

       **ldapi**:
           Like the _ldap_ URI scheme, but uses a UNIX domain socket.  The server methods are not
           supported, and the local socket path is available as $uri->un_path.  The _ldapi_ scheme is
           used by the OpenLDAP package.  There is no real specification for it, but it is mentioned
           in various OpenLDAP manual pages.

       **ldaps**:
           Like the _ldap_ URI scheme, but uses an SSL connection.  This scheme is deprecated, as the
           preferred way is to use the _start_tls_ mechanism.

       **mailto**:
           The _mailto_ URI scheme is specified in RFC 2368.  The scheme was originally used to
           designate the Internet mailing address of an individual or service.  It has (in RFC 2368)
           been extended to allow setting of other mail header fields and the message body.

           "URI" objects belonging to the mailto scheme support the common methods and the generic
           query methods.  In addition, they support the following mailto-specific methods:
           $uri->to, $uri->headers.

           Note that the "<foo@example.com>" part of a mailto is _not_ the "userinfo" and "host" but
           instead the "path".  This allows a mailto URI to contain multiple comma separated email
           addresses.

       **mms**:
           The _mms_ URL specification can be found at <<http://sdp.ppona.com/>>.  "URI" objects
           belonging to the mms scheme support the common, generic, and server methods, with the
           exception of userinfo and query-related sub-components.

       **news**:
           The _news_, _nntp_ and _snews_ URI schemes are specified in <draft-gilman-news-url-01> and will
           hopefully be available as an RFC 2396 based specification soon. (Update: as of April
           2010, they are in RFC 5538 <<https://tools.ietf.org/html/rfc5538>>.

           "URI" objects belonging to the news scheme support the common, generic and server
           methods.  In addition, they provide some methods to access the path: $uri->group and
           $uri->message.

       **nntp**:
           See _news_ scheme.

       **nntps**:
           See _news_ scheme and RFC 5538 <<https://tools.ietf.org/html/rfc5538>>.

       **pop**:
           The _pop_ URI scheme is specified in RFC 2384. The scheme is used to reference a POP3
           mailbox.

           "URI" objects belonging to the pop scheme support the common, generic and server methods.
           In addition, they provide two methods to access the userinfo components: $uri->user and
           $uri->auth

       **rlogin**:
           An old specification of the _rlogin_ URI scheme is found in RFC 1738. "URI" objects
           belonging to the rlogin scheme support the common, generic and server methods.

       **rtsp**:
           The _rtsp_ URL specification can be found in section 3.2 of RFC 2326.  "URI" objects
           belonging to the rtsp scheme support the common, generic, and server methods, with the
           exception of userinfo and query-related sub-components.

       **rtspu**:
           The _rtspu_ URI scheme is used to talk to RTSP servers over UDP instead of TCP.  The syntax
           is the same as rtsp.

       **rsync**:
           Information about rsync is available from <<http://rsync.samba.org/>>.  "URI" objects
           belonging to the rsync scheme support the common, generic and server methods.  In
           addition, they provide methods to access the userinfo sub-components: $uri->user and
           $uri->password.

       **sip**:
           The _sip_ URI specification is described in sections 19.1 and 25 of RFC 3261.  "URI"
           objects belonging to the sip scheme support the common, generic, and server methods with
           the exception of path related sub-components.  In addition, they provide two methods to
           get and set _sip_ parameters: $uri->params_form and $uri->params.

       **sips**:
           See _sip_ scheme.  Its syntax is the same as sip, but the default port is different.

       **snews**:
           See _news_ scheme.  Its syntax is the same as news, but the default port is different.

       **telnet**:
           An old specification of the _telnet_ URI scheme is found in RFC 1738. "URI" objects
           belonging to the telnet scheme support the common, generic and server methods.

       **tn3270**:
           These URIs are used like _telnet_ URIs but for connections to IBM mainframes.  "URI"
           objects belonging to the tn3270 scheme support the common, generic and server methods.

       **ssh**:
           Information about ssh is available at <<http://www.openssh.com/>>.  "URI" objects belonging
           to the ssh scheme support the common, generic and server methods. In addition, they
           provide methods to access the userinfo sub-components: $uri->user and $uri->password.

       **sftp**:
           "URI" objects belonging to the sftp scheme support the common, generic and server
           methods. In addition, they provide methods to access the userinfo sub-components:
           $uri->user and $uri->password.

       **urn**:
           The syntax of Uniform Resource Names is specified in RFC 2141.  "URI" objects belonging
           to the urn scheme provide the common methods, and also the methods $uri->nid and
           $uri->nss, which return the Namespace Identifier and the Namespace-Specific String
           respectively.

           The Namespace Identifier basically works like the Scheme identifier of URIs, and further
           divides the URN namespace.  Namespace Identifier assignments are maintained at
           <<http://www.iana.org/assignments/urn-namespaces>>.

           Letter case is not significant for the Namespace Identifier.  It is always returned in
           lower case by the $uri->nid method.  The $uri->_nid method can be used if you want it in
           its original case.

       **urn**:**isbn**:
           The "urn:isbn:" namespace contains International Standard Book Numbers (ISBNs) and is
           described in RFC 3187.  A "URI" object belonging to this namespace has the following
           extra methods (if the [Business::ISBN](https://www.chedong.com/phpMan.php/perldoc/Business%3A%3AISBN/markdown) module is available): $uri->isbn,
           $uri->isbn_publisher_code, $uri->isbn_group_code (formerly isbn_country_code, which is
           still supported by issues a deprecation warning), $uri->isbn_as_ean.

       **urn**:**oid**:
           The "urn:oid:" namespace contains Object Identifiers (OIDs) and is described in RFC 3061.
           An object identifier consists of sequences of digits separated by dots.  A "URI" object
           belonging to this namespace has an additional method called $uri->oid that can be used to
           get/set the oid value.  In a list context, oid numbers are returned as separate elements.

## CONFIGURATION VARIABLES
       The following configuration variables influence how the class and its methods behave:

       $[URI::ABS_ALLOW_RELATIVE_SCHEME](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3AABSALLOWRELATIVESCHEME/markdown)
           Some older parsers used to allow the scheme name to be present in the relative URL if it
           was the same as the base URL scheme.  RFC 2396 says that this should be avoided, but you
           can enable this old behaviour by setting the $[URI::ABS_ALLOW_RELATIVE_SCHEME](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3AABSALLOWRELATIVESCHEME/markdown) variable to
           a TRUE value.  The difference is demonstrated by the following examples:

             URI->new("http:foo")->abs("<http://host/a/b>")
                 ==>  "http:foo"

             local $[URI::ABS_ALLOW_RELATIVE_SCHEME](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3AABSALLOWRELATIVESCHEME/markdown) = 1;
             URI->new("http:foo")->abs("<http://host/a/b>")
                 ==>  "http:/host/a/foo"

       $[URI::ABS_REMOTE_LEADING_DOTS](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3AABSREMOTELEADINGDOTS/markdown)
           You can also have the **abs()** method ignore excess ".."  segments in the relative URI by
           setting $[URI::ABS_REMOTE_LEADING_DOTS](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3AABSREMOTELEADINGDOTS/markdown) to a TRUE value.  The difference is demonstrated by
           the following examples:

             URI->new("../../../foo")->abs("<http://host/a/b>")
                 ==> "<http://host/../../foo>"

             local $[URI::ABS_REMOTE_LEADING_DOTS](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3AABSREMOTELEADINGDOTS/markdown) = 1;
             URI->new("../../../foo")->abs("<http://host/a/b>")
                 ==> "<http://host/foo>"

       $[URI::DEFAULT_QUERY_FORM_DELIMITER](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3ADEFAULTQUERYFORMDELIMITER/markdown)
           This value can be set to ";" to have the query form "key=value" pairs delimited by ";"
           instead of "&" which is the default.

## BUGS
       There are some things that are not quite right:

       •   Using regexp variables like $1 directly as arguments to the URI accessor methods does not
           work too well with current perl implementations.  I would argue that this is actually a
           bug in perl.  The workaround is to quote them. Example:

              /(...)/ || die;
              $u->query("$1");

       •   The escaping (percent encoding) of chars in the 128 .. 255 range passed to the URI
           constructor or when setting URI parts using the accessor methods depend on the state of
           the internal UTF8 flag (see [utf8::is_utf8](https://www.chedong.com/phpMan.php/perldoc/utf8%3A%3Aisutf8/markdown)) of the string passed.  If the UTF8 flag is set
           the UTF-8 encoded version of the character is percent encoded.  If the UTF8 flag isn't
           set the Latin-1 version (byte) of the character is percent encoded.  This basically
           exposes the internal encoding of Perl strings.

### PARSING URIs WITH REGEXP
       As an alternative to this module, the following (official) regular expression can be used to
       decode a URI:

         my($scheme, $authority, $path, $query, $fragment) =
         $uri =~ m|(?:([^:/?#]+):)?(?://([^/?#]*))?([^?#]*)(?:\?([^#]*))?(?:#(.*))?|;

       The "[URI::Split](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3ASplit/markdown)" module provides the function **uri**___**split()** as a readable alternative.

## SEE ALSO
       [URI::file](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3Afile/markdown), [URI::WithBase](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3AWithBase/markdown), [URI::QueryParam](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3AQueryParam/markdown), [URI::Escape](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3AEscape/markdown), [URI::Split](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3ASplit/markdown), [URI::Heuristic](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3AHeuristic/markdown)

       RFC 2396: "Uniform Resource Identifiers (URI): Generic Syntax", Berners-Lee, Fielding,
       Masinter, August 1998.

       <<http://www.iana.org/assignments/uri-schemes>>

       <<http://www.iana.org/assignments/urn-namespaces>>

       <<http://www.w3.org/Addressing/>>

## COPYRIGHT
       Copyright 1995-2009 Gisle Aas.

       Copyright 1995 Martijn Koster.

       This program is free software; you can redistribute it and/or modify it under the same terms
       as Perl itself.

## AUTHORS / ACKNOWLEDGMENTS
       This module is based on the "[URI::URL](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3AURL/markdown)" module, which in turn was (distantly) based on the
       "wwwurl.pl" code in the libwww-perl for perl4 developed by Roy Fielding, as part of the
       Arcadia project at the University of California, Irvine, with contributions from Brooks
       Cutter.

       "[URI::URL](https://www.chedong.com/phpMan.php/perldoc/URI%3A%3AURL/markdown)" was developed by Gisle Aas, Tim Bunce, Roy Fielding and Martijn Koster with input
       from other people on the libwww-perl mailing list.

       "URI" and related subclasses was developed by Gisle Aas.



perl v5.32.1                                 2021-10-26                                     [URI(3pm)](https://www.chedong.com/phpMan.php/man/URI/3pm/markdown)
