CTAGS(1)                        Exuberant Ctags                       CTAGS(1)



NAME
       ctags - Generate tag files for source code



SYNOPSIS
       ctags [options] [file(s)]

       etags [options] [file(s)]



DESCRIPTION
       The ctags and etags programs (hereinafter collectively referred to as
       ctags, except where distinguished) generate an index (or "tag") file
       for a variety of language objects found in file(s).  This tag file
       allows these items to be quickly and easily located by a text editor or
       other utility. A "tag" signifies a language object for which an index
       entry is available (or, alternatively, the index entry created for that
       object).

       Alternatively, ctags can generate a cross reference file which lists,
       in human readable form, information about the various source objects
       found in a set of language files.

       Tag index files are supported by numerous editors, which allow the user
       to locate the object associated with a name appearing in a source file
       and jump to the file and line which defines the name. Those known about
       at the time of this release are:

           Vi(1) and its derivatives (e.g. Elvis, Vim, Vile, Lemmy), CRiSP,
           Emacs, FTE (Folding Text Editor), JED, jEdit, Mined, NEdit (Nirvana
           Edit), TSE (The SemWare Editor), UltraEdit, WorkSpace, X2, Zeus

       Ctags is capable of generating different kinds of tags for each of many
       different languages. For a complete list of supported languages, the
       names by which they are recognized, and the kinds of tags which are
       generated for each, see the --list-languages and --list-kinds options.



SOURCE FILES
       Unless the --language-force option is specified, the language of each
       source file is automatically selected based upon a mapping of file
       names to languages. The mappings in effect for each language may be
       display using the --list-maps option and may be changed using the
       --langmap option.  On platforms which support it, if the name of a file
       is not mapped to a language and the file is executable, the first line
       of the file is checked to see if the file is a "#!" script for a
       recognized language.

       By default, all other files names are ignored. This permits running
       ctags on all files in either a single directory (e.g. "ctags *"), or on
       all files in an entire source directory tree (e.g. "ctags -R"), since
       only those files whose names are mapped to languages will be scanned.

       [The reason that .h extensions are mapped to C++ files rather than C
       files is because it is common to use .h extensions in C++, and no harm
       results in treating them as C++ files.]



OPTIONS
       Despite the wealth of available options, defaults are set so that ctags
       is most commonly executed without any options (e.g. "ctags *", or
       "ctags -R"), which will create a tag file in the current directory for
       all recognized source files. The options described below are provided
       merely to allow custom tailoring to meet special needs.

       Note that spaces separating the single-letter options from their
       parameters are optional.

       Note also that the boolean parameters to the long form options (those
       beginning with "--" and that take a "[=yes|no]" parameter) may be
       omitted, in which case "=yes" is implied. (e.g. --sort is equivalent to
       --sort=yes). Note further that "=1" and "=on" are considered synonyms
       for "=yes", and that "=0" and "=off" are considered synonyms for "=no".

       Some options are either ignored or useful only when used while running
       in etags mode (see -e option). Such options will be noted.

       Most options may appear anywhere on the command line, affecting only
       those files which follow the option. A few options, however, must
       appear before the first file name and will be noted as such.

       Options taking language names will accept those names in either upper
       or lower case. See the --list-languages option for a complete list of
       the built-in language names.


       -a   Equivalent to --append.


       -B   Use backward searching patterns (e.g. ?pattern?). [Ignored in
            etags mode]


       -e   Enable etags mode, which will create a tag file for use with the
            Emacs editor.  Alternatively, if ctags is invoked by a name
            containing the string "etags" (either by renaming, or creating a
            link to, the executable), etags mode will be enabled. This option
            must appear before the first file name.


       -f tagfile
            Use the name specified by tagfile for the tag file (default is
            "tags", or "TAGS" when running in etags mode). If tagfile is
            specified as "-", then the tag file is written to standard output
            instead. Ctags will stubbornly refuse to take orders if tagfile
            exists and its first line contains something other than a valid
            tags line. This will save your neck if you mistakenly type "ctags
            -f *.c", which would otherwise overwrite your first C file with
            the tags generated by the rest! It will also refuse to accept a
            multi-character file name which begins with a '-' (dash)
            character, since this most likely means that you left out the tag
            file name and this option tried to grab the next option as the
            file name. If you really want to name your output tag file
            "-ugly", specify it as "./-ugly". This option must appear before
            the first file name. If this option is specified more than once,
            only the last will apply.


       -F   Use forward searching patterns (e.g. /pattern/) (default).
            [Ignored in etags mode]


       -h list
            Specifies a list of file extensions, separated by periods, which
            are to be interpreted as include (or header) files. To indicate
            files having no extension, use a period not followed by a non-
            period character (e.g. ".", "..x", ".x."). This option only
            affects how the scoping of a particular kinds of tags is
            interpreted (i.e. whether or not they are considered as globally
            visible or visible only within the file in which they are
            defined); it does not map the extension to any particular
            language. Any tag which is located in a non-include file and
            cannot be seen (e.g. linked to) from another file is considered to
            have file-limited (e.g. static) scope. No kind of tag appearing in
            an include file will be considered to have file-limited scope. If
            the first character in the list is a plus sign, then the
            extensions in the list will be appended to the current list;
            otherwise, the list will replace the current list. See, also, the
            --file-scope option. The default list is
            ".h.H.hh.hpp.hxx.h++.inc.def". To restore the default list,
            specify -h default. Note that if an extension supplied to this
            option is not already mapped to a particular language (see SOURCE
            FILES, above), you will also need to use either the --langmap or
            --language-force option.


       -I identifier-list
            Specifies a list of identifiers which are to be specially handled
            while parsing C and C++ source files. This option is specifically
            provided to handle special cases arising through the use of
            preprocessor macros. When the identifiers listed are simple
            identifiers, these identifiers will be ignored during parsing of
            the source files. If an identifier is suffixed with a '+'
            character, ctags will also ignore any parenthesis-enclosed
            argument list which may immediately follow the identifier in the
            source files. If two identifiers are separated with the '='
            character, the first identifiers is replaced by the second
            identifiers for parsing purposes. The list of identifiers may be
            supplied directly on the command line or read in from a separate
            file. If the first character of identifier-list is '@', '.' or a
            pathname separator ('/' or '\'), or the first two characters
            specify a drive letter (e.g. "C:"), the parameter identifier-list
            will be interpreted as a filename from which to read a list of
            identifiers, one per input line. Otherwise, identifier-list is a
            list of identifiers (or identifier pairs) to be specially handled,
            each delimited by a either a comma or by white space (in which
            case the list should be quoted to keep the entire list as one
            command line argument). Multiple -I options may be supplied.  To
            clear the list of ignore identifiers, supply a single dash ("-")
            for identifier-list.

            This feature is useful when preprocessor macros are used in such a
            way that they cause syntactic confusion due to their presence.
            Indeed, this is the best way of working around a number of
            problems caused by the presence of syntax-busting macros in source
            files (see CAVEATS, below). Some examples will illustrate this
            point.

               int foo ARGDECL4(void *, ptr, long int, nbytes)


            In the above example, the macro "ARGDECL4" would be mistakenly
            interpreted to be the name of the function instead of the correct
            name of "foo". Specifying -I ARGDECL4 results in the correct
            behavior.

               /* creates an RCS version string in module */
               MODULE_VERSION("$Revision: 690 $")


            In the above example the macro invocation looks too much like a
            function definition because it is not followed by a semicolon
            (indeed, it could even be followed by a global variable definition
            that would look much like a K&R style function parameter
            declaration). In fact, this seeming function definition could
            possibly even cause the rest of the file to be skipped over while
            trying to complete the definition. Specifying -I MODULE_VERSION+
            would avoid such a problem.

               CLASS Example {
                   // your content here
               };


            The example above uses "CLASS" as a preprocessor macro which
            expands to something different for each platform. For instance
            CLASS may be defined as "class __declspec(dllexport)" on Win32
            platforms and simply "class" on UNIX.  Normally, the absence of
            the C++ keyword "class" would cause the source file to be
            incorrectly parsed. Correct behavior can be restored by specifying
            -I CLASS=class.


       -L file
            Read from file a list of file names for which tags should be
            generated.  If file is specified as "-", then file names are read
            from standard input. File names read using this option are
            processed following file names appearing on the command line.
            Options are also accepted in this input. If this option is
            specified more than once, only the last will apply. Note: file is
            read in line-oriented mode, where a new line is the only delimiter
            and non-trailing white space is considered significant, in order
            that file names containing spaces may be supplied (however,
            trailing white space is stripped from lines); this can affect how
            options are parsed if included in the input.


       -n   Equivalent to --excmd=number.


       -N   Equivalent to --excmd=pattern.


       -o tagfile
            Equivalent to -f tagfile.


       -R   Equivalent to --recurse.


       -u   Equivalent to --sort=no (i.e. "unsorted").


       -V   Equivalent to --verbose.


       -w   This option is silently ignored for backward-compatibility with
            the ctags of SVR4 Unix.


       -x   Print a tabular, human-readable cross reference (xref) file to
            standard output instead of generating a tag file. The information
            contained in the output includes: the tag name; the kind of tag;
            the line number, file name, and source line (with extra white
            space condensed) of the file which defines the tag. No tag file is
            written and all options affecting tag file output will be ignored.
            Example applications for this feature are generating a listing of
            all functions located in a source file (e.g. ctags -x --c-kinds=f
            file), or generating a list of all externally visible global
            variables located in a source file (e.g. ctags -x --c-kinds=v
            --file-scope=no file). This option must appear before the first
            file name.


       --append[=yes|no]
            Indicates whether tags generated from the specified files should
            be appended to those already present in the tag file or should
            replace them. This option is off by default. This option must
            appear before the first file name.


       --etags-include=file
            Include a reference to file in the tag file. This option may be
            specified as many times as desired. This supports Emacs'
            capability to use a tag file which "includes" other tag files.
            [Available only in etags mode]


       --exclude=[pattern]
            Add pattern to a list of excluded files and directories. This
            option may be specified as many times as desired. For each file
            name considered by ctags, each pattern specified using this option
            will be compared against both the complete path (e.g.
            some/path/base.ext) and the base name (e.g. base.ext) of the file,
            thus allowing patterns which match a given file name irrespective
            of its path, or match only a specific path. If appropriate support
            is available from the runtime library of your C compiler, then
            pattern may contain the usual shell wildcards (not regular
            expressions) common on Unix (be sure to quote the option parameter
            to protect the wildcards from being expanded by the shell before
            being passed to ctags; also be aware that wildcards can match the
            slash character, '/'). You can determine if shell wildcards are
            available on your platform by examining the output of the
            --version option, which will include "+wildcards" in the compiled
            feature list; otherwise, pattern is matched against file names
            using a simple textual comparison.

            If pattern begins with the character '@', then the rest of the
            string is interpreted as a file name from which to read exclusion
            patterns, one per line. If pattern is empty, the list of excluded
            patterns is cleared.  Note that at program startup, the default
            exclude list contains "EIFGEN", "SCCS", "RCS", and "CVS", which
            are names of directories for which it is generally not desirable
            to descend while processing the --recurse option.


       --excmd=type
            Determines the type of EX command used to locate tags in the
            source file.  [Ignored in etags mode]

            The valid values for type (either the entire word or the first
            letter is accepted) are:


            number   Use only line numbers in the tag file for locating tags.
                     This has four advantages:
                     1.  Significantly reduces the size of the resulting tag
                         file.
                     2.  Eliminates failures to find tags because the line
                         defining the tag has changed, causing the pattern
                         match to fail (note that some editors, such as vim,
                         are able to recover in many such instances).
                     3.  Eliminates finding identical matching, but incorrect,
                         source lines (see BUGS, below).
                     4.  Retains separate entries in the tag file for lines
                         which are identical in content. In pattern mode,
                         duplicate entries are dropped because the search
                         patterns they generate are identical, making the
                         duplicate entries useless.


                     However, this option has one significant drawback:
                     changes to the source files can cause the line numbers
                     recorded in the tag file to no longer correspond to the
                     lines in the source file, causing jumps to some tags to
                     miss the target definition by one or more lines.
                     Basically, this option is best used when the source code
                     to which it is applied is not subject to change.
                     Selecting this option type causes the following options
                     to be ignored: -BF.


            pattern  Use only search patterns for all tags, rather than the
                     line numbers usually used for macro definitions. This has
                     the advantage of not referencing obsolete line numbers
                     when lines have been added or removed since the tag file
                     was generated.


            mixed    In this mode, patterns are generally used with a few
                     exceptions. For C, line numbers are used for macro
                     definition tags. This was the default format generated by
                     the original ctags and is, therefore, retained as the
                     default for this option. For Fortran, line numbers are
                     used for common blocks because their corresponding source
                     lines are generally identical, making pattern searches
                     useless for finding all matches.


       --extra=[+|-]flags
            Specifies whether to include extra tag entries for certain kinds
            of information. The parameter flags is a set of one-letter flags,
            each representing one kind of extra tag entry to include in the
            tag file. If flags is preceded by by either the '+' or '-'
            character, the effect of each flag is added to, or removed from,
            those currently enabled; otherwise the flags replace any current
            settings. The meaning of each flag is as follows:


               f   Include an entry for the base file name of every source
                   file (e.g.  "example.c"), which addresses the first line of
                   the file.

               q   Include an extra class-qualified tag entry for each tag
                   which is a member of a class (for languages for which this
                   information is extracted; currently C++, Eiffel, and Java).
                   The actual form of the qualified tag depends upon the
                   language from which the tag was derived (using a form that
                   is most natural for how qualified calls are specified in
                   the language). For C++, it is in the form "class::member";
                   for Eiffel and Java, it is in the form "class.member". This
                   may allow easier location of a specific tags when multiple
                   occurrences of a tag name occur in the tag file. Note,
                   however, that this could potentially more than double the
                   size of the tag file.


       --fields=[+|-]flags
            Specifies the available extension fields which are to be included
            in the entries of the tag file (see TAG FILE FORMAT, below, for
            more information). The parameter flags is a set of one-letter
            flags, each representing one type of extension field to include,
            with the following meanings (disabled by default unless
            indicated):


               a   Access (or export) of class members
               f   File-restricted scoping [enabled]
               i   Inheritance information
               k   Kind of tag as a single letter [enabled]
               K   Kind of tag as full name
               l   Language of source file containing tag
               m   Implementation information
               n   Line number of tag definition
               s   Scope of tag definition [enabled]
               S   Signature of routine (e.g. prototype or parameter list)
               z   Include the "kind:" key in kind field
               t   Type and name of a variable or typedef as "typeref:" field
                   [enabled]

            Each letter or group of letters may be preceded by either '+' to
            add it to the default set, or '-' to exclude it. In the absence of
            any preceding '+' or '-' sign, only those kinds explicitly listed
            in flags will be included in the output (i.e. overriding the
            default set). This option is ignored if the option --format=1 has
            been specified. The default value of this option is fkst.


       --file-scope[=yes|no]
            Indicates whether tags scoped only for a single file (i.e. tags
            which cannot be seen outside of the file in which they are
            defined, such as "static" tags) should be included in the output.
            See, also, the -h option. This option is enabled by default.


       --filter[=yes|no]
            Causes ctags to behave as a filter, reading source file names from
            standard input and printing their tags to standard output on a
            file-by-file basis. If --sorted is enabled, tags are sorted only
            within the source file in which they are defined. File names are
            read from standard input in line-oriented input mode (see note for
            -L option) and only after file names listed on the command line or
            from any file supplied using the -L option. When this option is
            enabled, the options -f, -o, and --totals are ignored. This option
            is quite esoteric and is disabled by default. This option must
            appear before the first file name.


       --filter-terminator=string
            Specifies a string to print to standard output following the tags
            for each file name parsed when the --filter option is enabled.
            This may permit an application reading the output of ctags to
            determine when the output for each file is finished. Note that if
            the file name read is a directory and --recurse is enabled, this
            string will be printed only one once at the end of all tags found
            for by descending the directory. This string will always be
            separated from the last tag line for the file by its terminating
            newline.  This option is quite esoteric and is empty by default.
            This option must appear before the first file name.


       --format=level
            Change the format of the output tag file. Currently the only valid
            values for level are 1 or 2. Level 1 specifies the original tag
            file format and level 2 specifies a new extended format containing
            extension fields (but in a manner which retains backward-
            compatibility with original vi(1) implementations). The default
            level is 2. This option must appear before the first file name.
            [Ignored in etags mode]


       --help
            Prints to standard output a detailed usage description, and then
            exits.


       --if0[=yes|no]
            Indicates a preference as to whether code within an "#if 0" branch
            of a preprocessor conditional should be examined for non-macro
            tags (macro tags are always included). Because the intent of this
            construct is to disable code, the default value of this option is
            no. Note that this indicates a preference only and does not
            guarantee skipping code within an "#if 0" branch, since the fall-
            back algorithm used to generate tags when preprocessor
            conditionals are too complex follows all branches of a
            conditional. This option is disabled by default.


       --<LANG>-kinds=[+|-]kinds
            Specifies a list of language-specific kinds of tags (or kinds) to
            include in the output file for a particular language, where <LANG>
            is case-insensitive and is one of the built-in language names (see
            the --list-languages option for a complete list). The parameter
            kinds is a group of one-letter flags designating kinds of tags
            (particular to the language) to either include or exclude from the
            output. The specific sets of flags recognized for each language,
            their meanings and defaults may be list using the --list-kinds
            option. Each letter or group of letters may be preceded by either
            '+' to add it to, or '-' to remove it from, the default set. In
            the absence of any preceding '+' or '-' sign, only those kinds
            explicitly listed in kinds will be included in the output (i.e.
            overriding the default for the specified language).

            As an example for the C language, in order to add prototypes and
            external variable declarations to the default set of tag kinds,
            but exclude macros, use --c-kinds=+px-d; to include only tags for
            functions, use --c-kinds=f.


       --langdef=name
            Defines a new user-defined language, name, to be parsed with
            regular expressions. Once defined, name may be used in other
            options taking language names. The typical use of this option is
            to first define the language, then map file names to it using
            --langmap, then specify regular expressions using --regex-<LANG>
            to define how its tags are found.


       --langmap=map[,map[...]]
            Controls how file names are mapped to languages (see the
            --list-maps option). Each comma-separated map consists of the
            language name (either a built-in or user-defined language), a
            colon, and a list of file extensions and/or file name patterns. A
            file extension is specified by preceding the extension with a
            period (e.g. ".c"). A file name pattern is specified by enclosing
            the pattern in parentheses (e.g. "([Mm]akefile)"). If appropriate
            support is available from the runtime library of your C compiler,
            then the file name pattern may contain the usual shell wildcards
            common on Unix (be sure to quote the option parameter to protect
            the wildcards from being expanded by the shell before being passed
            to ctags). You can determine if shell wildcards are available on
            your platform by examining the output of the --version option,
            which will include "+wildcards" in the compiled feature list;
            otherwise, the file name patterns are matched against file names
            using a simple textual comparison. When mapping a file extension,
            it will first be unmapped from any other languages.

            If the first character in a map is a plus sign, then the
            extensions and file name patterns in that map will be appended to
            the current map for that language; otherwise, the map will replace
            the current map. For example, to specify that only files with
            extensions of .c and .x are to be treated as C language files, use
            "--langmap=c:.c.x"; to also add files with extensions of .j as
            Java language files, specify "--langmap=c:.c.x,java:+.j". To map
            makefiles (e.g. files named either "Makefile", "makefile", or
            having the extension ".mak") to a language called "make", specify
            "--langmap=make:([Mm]akefile).mak".  To map files having no
            extension, specify a period not followed by a non-period character
            (e.g. ".", "..x", ".x."). To clear the mapping for a particular
            language (thus inhibiting automatic generation of tags for that
            language), specify an empty extension list (e.g.
            "--langmap=fortran:"). To restore the default language mappings
            for all a particular language, supply the keyword "default" for
            the mapping.  To specify restore the default language mappings for
            all languages, specify "--langmap=default". Note that file
            extensions are tested before file name patterns when inferring the
            language of a file.


       --language-force=language
            By default, ctags automatically selects the language of a source
            file, ignoring those files whose language cannot be determined
            (see SOURCE FILES, above). This option forces the specified
            language (case-insensitive; either built-in or user-defined) to be
            used for every supplied file instead of automatically selecting
            the language based upon its extension. In addition, the special
            value auto indicates that the language should be automatically
            selected (which effectively disables this option).


       --languages=[+|-]list
            Specifies the languages for which tag generation is enabled, with
            list containing a comma-separated list of language names (case-
            insensitive; either built-in or user-defined). If the first
            language of list is not preceded by either a '+' or '-', the
            current list will be cleared before adding or removing the
            languages in list. Until a '-' is encountered, each language in
            the list will be added to the current list. As either the '+' or
            '-' is encountered in the list, the languages following it are
            added or removed from the current list, respectively. Thus, it
            becomes simple to replace the current list with a new one, or to
            add or remove languages from the current list. The actual list of
            files for which tags will be generated depends upon the language
            extension mapping in effect (see the --langmap option). Note that
            all languages, including user-defined languages are enabled unless
            explicitly disabled using this option. Language names included in
            list may be any built-in language or one previously defined with
            --langdef. The default is "all", which is also accepted as a valid
            argument. See the --list-languages option for a complete list of
            the built-in language names.


       --license
            Prints a summary of the software license to standard output, and
            then exits.


       --line-directives[=yes|no]
            Specifies whether "#line" directives should be recognized. These
            are present in the output of preprocessors and contain the line
            number, and possibly the file name, of the original source file(s)
            from which the preprocessor output file was generated. When
            enabled, this option will cause ctags to generate tag entries
            marked with the file names and line numbers of their locations
            original source file(s), instead of their actual locations in the
            preprocessor output. The actual file names placed into the tag
            file will have the same leading path components as the
            preprocessor output file, since it is assumed that the original
            source files are located relative to the preprocessor output file
            (unless, of course, the #line directive specifies an absolute
            path). This option is off by default. Note: This option is
            generally only useful when used together with the --excmd=number
            (-n) option. Also, you may have to use either the --langmap or
            --language-force option if the extension of the preprocessor
            output file is not known to ctags.


       --links[=yes|no]
            Indicates whether symbolic links (if supported) should be
            followed. When disabled, symbolic links are ignored. This option
            is on by default.


       --list-kinds[=language|all]
            Lists the tag kinds recognized for either the specified language
            or all languages, and then exits. Each kind of tag recorded in the
            tag file is represented by a one-letter flag, which is also used
            to filter the tags placed into the output through use of the
            --<LANG>-kinds option. Note that some languages and/or tag kinds
            may be implemented using regular expressions and may not be
            available if regex support is not compiled into ctags (see the
            --regex-<LANG> option). Each kind listed is enabled unless
            followed by "[off]".


       --list-maps[=language|all]
            Lists the file extensions and file name patterns which associate a
            file name with a language for either the specified language or all
            languages, and then exits. See the --langmap option, and SOURCE
            FILES, above.


       --list-languages
            Lists the names of the languages understood by ctags, and then
            exits.  These language names are case insensitive and may be used
            in the --language-force, --languages, --<LANG>-kinds, and
            --regex-<LANG> options.


       --options=file
            Read additional options from file. The file should contain one
            option per line. As a special case, if --options=NONE is specified
            as the first option on the command line, it will disable the
            automatic reading of any configuration options from either a file
            or the environment (see FILES).


       --recurse[=yes|no]
            Recurse into directories encountered in the list of supplied
            files. If the list of supplied files is empty and no file list is
            specified with the -L option, then the current directory (i.e.
            ".") is assumed. Symbolic links are followed. If you don't like
            these behaviors, either explicitly specify the files or pipe the
            output of find(1) into ctags -L- instead. Note: This option is not
            supported on all platforms at present.  It is available if the
            output of the --help option includes this option.  See, also, the
            --exclude to limit recursion.


       --regex-<LANG>=/regexp/replacement/[kind-spec/][flags]
            The /regexp/replacement/ pair define a regular expression
            replacement pattern, similar in style to sed substitution
            commands, with which to generate tags from source files mapped to
            the named language, <LANG>, (case-insensitive; either a built-in
            or user-defined language). The regular expression, regexp, defines
            an extended regular expression (roughly that used by egrep(1)),
            which is used to locate a single source line containing a tag and
            may specify tab characters using \t. When a matching line is
            found, a tag will be generated for the name defined by
            replacement, which generally will contain the special back-
            references \1 through \9 to refer to matching sub-expression
            groups within regexp. The '/' separator characters shown in the
            parameter to the option can actually be replaced by any character.
            Note that whichever separator character is used will have to be
            escaped with a backslash ('\') character wherever it is used in
            the parameter as something other than a separator. The regular
            expression defined by this option is added to the current list of
            regular expressions for the specified language unless the
            parameter is omitted, in which case the current list is cleared.

            Unless modified by flags, regexp is interpreted as a Posix
            extended regular expression. The replacement should expand for all
            matching lines to a non-empty string of characters, or a warning
            message will be reported. An optional kind specifier for tags
            matching regexp may follow replacement, which will determine what
            kind of tag is reported in the "kind" extension field (see TAG
            FILE FORMAT, below). The full form of kind-spec is in the form of
            a single letter, a comma, a name (without spaces), a comma, a
            description, followed by a separator, which specify the short and
            long forms of the kind value and its textual description
            (displayed using --list-kinds). Either the kind name and/or the
            description may be omitted. If kind-spec is omitted, it defaults
            to "r,regex". Finally, flags are one or more single-letter
            characters having the following effect upon the interpretation of
            regexp:


               b   The pattern is interpreted as a Posix basic regular
                   expression.

               e   The pattern is interpreted as a Posix extended regular
                   expression (default).

               i   The regular expression is to be applied in a case-
                   insensitive manner.

            Note that this option is available only if ctags was compiled with
            support for regular expressions, which depends upon your platform.
            You can determine if support for regular expressions is compiled
            in by examining the output of the --version option, which will
            include "+regex" in the compiled feature list.

            For more information on the regular expressions used by ctags, see
            either the regex(5,7) man page, or the GNU info documentation for
            regex (e.g. "info regex").


       --sort[=yes|no|foldcase]
            Indicates whether the tag file should be sorted on the tag name
            (default is yes). Note that the original vi(1) required sorted
            tags.  The foldcase value specifies case insensitive (or case-
            folded) sorting.  Fast binary searches of tag files sorted with
            case-folding will require special support from tools using tag
            files, such as that found in the ctags readtags library, or Vim
            version 6.2 or higher (using "set ignorecase"). This option must
            appear before the first file name. [Ignored in etags mode]


       --tag-relative[=yes|no]
            Indicates that the file paths recorded in the tag file should be
            relative to the directory containing the tag file, rather than
            relative to the current directory, unless the files supplied on
            the command line are specified with absolute paths. This option
            must appear before the first file name. The default is yes when
            running in etags mode (see the -e option), no otherwise.


       --totals[=yes|no]
            Prints statistics about the source files read and the tag file
            written during the current invocation of ctags. This option is off
            by default.  This option must appear before the first file name.


       --verbose[=yes|no]
            Enable verbose mode. This prints out information on option
            processing and a brief message describing what action is being
            taken for each file considered by ctags. Normally, ctags does not
            read command line arguments until after options are read from the
            configuration files (see FILES, below) and the CTAGS environment
            variable. However, if this option is the first argument on the
            command line, it will take effect before any options are read from
            these sources. The default is no.


       --version
            Prints a version identifier for ctags to standard output, and then
            exits. This is guaranteed to always contain the string "Exuberant
            Ctags".



OPERATIONAL DETAILS
       As ctags considers each file name in turn, it tries to determine the
       language of the file by applying the following three tests in order: if
       the file extension has been mapped to a language, if the file name
       matches a shell pattern mapped to a language, and finally if the file
       is executable and its first line specifies an interpreter using the
       Unix-style "#!" specification (if supported on the platform). If a
       language was identified, the file is opened and then the appropriate
       language parser is called to operate on the currently open file. The
       parser parses through the file and adds an entry to the tag file for
       each language object it is written to handle. See TAG FILE FORMAT,
       below, for details on these entries.

       This implementation of ctags imposes no formatting requirements on C
       code as do legacy implementations. Older implementations of ctags
       tended to rely upon certain formatting assumptions in order to help it
       resolve coding dilemmas caused by preprocessor conditionals.

       In general, ctags tries to be smart about conditional preprocessor
       directives. If a preprocessor conditional is encountered within a
       statement which defines a tag, ctags follows only the first branch of
       that conditional (except in the special case of "#if 0", in which case
       it follows only the last branch). The reason for this is that failing
       to pursue only one branch can result in ambiguous syntax, as in the
       following example:

              #ifdef TWO_ALTERNATIVES
              struct {
              #else
              union {
              #endif
                  short a;
                  long b;
              }

       Both branches cannot be followed, or braces become unbalanced and ctags
       would be unable to make sense of the syntax.

       If the application of this heuristic fails to properly parse a file,
       generally due to complicated and inconsistent pairing within the
       conditionals, ctags will retry the file using a different heuristic
       which does not selectively follow conditional preprocessor branches,
       but instead falls back to relying upon a closing brace ("}") in column
       1 as indicating the end of a block once any brace imbalance results
       from following a #if conditional branch.

       Ctags will also try to specially handle arguments lists enclosed in
       double sets of parentheses in order to accept the following conditional
       construct:

              extern void foo __ARGS((int one, char two));

       Any name immediately preceding the "((" will be automatically ignored
       and the previous name will be used.

       C++ operator definitions are specially handled. In order for
       consistency with all types of operators (overloaded and conversion),
       the operator name in the tag file will always be preceded by the string
       "operator " (i.e. even if the actual operator definition was written as
       "operator<<").

       After creating or appending to the tag file, it is sorted by the tag
       name, removing identical tag lines.



TAG FILE FORMAT
       When not running in etags mode, each entry in the tag file consists of
       a separate line, each looking like this in the most general case:

        tag_name<TAB>file_name<TAB>ex_cmd;"<TAB>extension_fields

       The fields and separators of these lines are specified as follows:

           1.  tag name
           2.  single tab character
           3.  name of the file in which the object associated with the tag is
               located
           4.  single tab character
           5.  EX command used to locate the tag within the file; generally a
               search pattern (either /pattern/ or ?pattern?) or line number
               (see --excmd). Tag file format 2 (see --format) extends this EX
               command under certain circumstances to include a set of
               extension fields (described below) embedded in an EX comment
               immediately appended to the EX command, which leaves it
               backward-compatible with original vi(1) implementations.

       A few special tags are written into the tag file for internal purposes.
       These tags are composed in such a way that they always sort to the top
       of the file.  Therefore, the first two characters of these tags are
       used a magic number to detect a tag file for purposes of determining
       whether a valid tag file is being overwritten rather than a source
       file.

       Note that the name of each source file will be recorded in the tag file
       exactly as it appears on the command line. Therefore, if the path you
       specified on the command line was relative to the current directory,
       then it will be recorded in that same manner in the tag file. See,
       however, the --tag-relative option for how this behavior can be
       modified.

       Extension fields are tab-separated key-value pairs appended to the end
       of the EX command as a comment, as described above. These key value
       pairs appear in the general form "key:value". Their presence in the
       lines of the tag file are controlled by the --fields option. The
       possible keys and the meaning of their values are as follows:


       access      Indicates the visibility of this class member, where value
                   is specific to the language.


       file        Indicates that the tag has file-limited visibility. This
                   key has no corresponding value.


       kind        Indicates the type, or kind, of tag. Its value is either
                   one of the corresponding one-letter flags described under
                   the various --<LANG>-kinds options above, or a full name.
                   It is permitted (and is, in fact, the default) for the key
                   portion of this field to be omitted. The optional behaviors
                   are controlled with the --fields option.


       implementation
                   When present, this indicates a limited implementation
                   (abstract vs. concrete) of a routine or class, where value
                   is specific to the language ("virtual" or "pure virtual"
                   for C++; "abstract" for Java).


       inherits    When present, value. is a comma-separated list of classes
                   from which this class is derived (i.e. inherits from).


       signature   When present, value is a language-dependent representation
                   of the signature of a routine. A routine signature in its
                   complete form specifies the return type of a routine and
                   its formal argument list. This extension field is presently
                   supported only for C-based languages and does not include
                   the return type.


       In addition, information on the scope of the tag definition may be
       available, with the key portion equal to some language-dependent
       construct name and its value the name declared for that construct in
       the program. This scope entry indicates the scope in which the tag was
       found. For example, a tag generated for a C structure member would have
       a scope looking like "struct:myStruct".



HOW TO USE WITH VI
       Vi will, by default, expect a tag file by the name "tags" in the
       current directory. Once the tag file is built, the following commands
       exercise the tag indexing feature:

       vi -t tag   Start vi and position the cursor at the file and line where
                   "tag" is defined.

       :ta tag     Find a tag.

       Ctrl-]      Find the tag under the cursor.

       Ctrl-T      Return to previous location before jump to tag (not widely
                   implemented).



HOW TO USE WITH GNU EMACS
       Emacs will, by default, expect a tag file by the name "TAGS" in the
       current directory. Once the tag file is built, the following commands
       exercise the tag indexing feature:

       M-x visit-tags-table <RET> FILE <RET>
                 Select the tag file, "FILE", to use.

       M-. [TAG] <RET>
                 Find the first definition of TAG. The default tag is the
                 identifier under the cursor.

       M-*       Pop back to where you previously invoked "M-.".

       C-u M-.   Find the next definition for the last tag.


       For more commands, see the Tags topic in the Emacs info document.



HOW TO USE WITH NEDIT
       NEdit version 5.1 and later can handle the new extended tag file format
       (see --format). To make NEdit use the tag file, select "File->Load Tags
       File". To jump to the definition for a tag, highlight the word, the
       press Ctrl-D. NEdit 5.1 can can read multiple tag files from different
       directories.  Setting the X resource nedit.tagFile to the name of a tag
       file instructs NEdit to automatically load that tag file at startup
       time.



CAVEATS
       Because ctags is neither a preprocessor nor a compiler, use of
       preprocessor macros can fool ctags into either missing tags or
       improperly generating inappropriate tags. Although ctags has been
       designed to handle certain common cases, this is the single biggest
       cause of reported problems. In particular, the use of preprocessor
       constructs which alter the textual syntax of C can fool ctags. You can
       work around many such problems by using the -I option.

       Note that since ctags generates patterns for locating tags (see the
       --excmd option), it is entirely possible that the wrong line may be
       found by your editor if there exists another source line which is
       identical to the line containing the tag. The following example
       demonstrates this condition:

              int variable;

              /* ... */
              void foo(variable)
              int variable;
              {
                  /* ... */
              }

       Depending upon which editor you use and where in the code you happen to
       be, it is possible that the search pattern may locate the local
       parameter declaration in foo() before it finds the actual global
       variable definition, since the lines (and therefore their search
       patterns are identical). This can be avoided by use of the --excmd=n
       option.



BUGS
       Ctags has more options than ls(1).

       When parsing a C++ member function definition (e.g.
       "className::function"), ctags cannot determine whether the scope
       specifier is a class name or a namespace specifier and always lists it
       as a class name in the scope portion of the extension fields. Also, if
       a C++ function is defined outside of the class declaration (the usual
       case), the access specification (i.e. public, protected, or private)
       and implementation information (e.g. virtual, pure virtual) contained
       in the function declaration are not known when the tag is generated for
       the function definition. It will, however be available for prototypes
       (e.g --c++-kinds=+p).

       No qualified tags are generated for language objects inherited into a
       class.



ENVIRONMENT VARIABLES
       CTAGS   If this environment variable exists, it will be expected to
               contain a set of default options which are read when ctags
               starts, after the configuration files listed in FILES, below,
               are read, but before any command line options are read. Options
               appearing on the command line will override options specified
               in this variable. Only options will be read from this variable.
               Note that all white space in this variable is considered a
               separator, making it impossible to pass an option parameter
               containing an embedded space. If this is a problem, use a
               configuration file instead.


       ETAGS   Similar to the CTAGS variable above, this variable, if found,
               will be read when etags starts. If this variable is not found,
               etags will try to use CTAGS instead.


       TMPDIR  On Unix-like hosts where mkstemp() is available, the value of
               this variable specifies the directory in which to place
               temporary files. This can be useful if the size of a temporary
               file becomes too large to fit on the partition holding the
               default temporary directory defined at compilation time.  ctags
               creates temporary files only if either (1) an emacs-style tag
               file is being generated, (2) the tag file is being sent to
               standard output, or (3) the program was compiled to use an
               internal sort algorithm to sort the tag files instead of the
               the sort utility of the operating system. If the sort utility
               of the operating system is being used, it will generally
               observe this variable also. Note that if ctags is setuid, the
               value of TMPDIR will be ignored.



FILES
       /ctags.cnf (on MSDOS, MSWindows only)
       /etc/ctags.conf
       /usr/local/etc/ctags.conf
       $HOME/.ctags
       $HOME/ctags.cnf (on MSDOS, MSWindows only)
       .ctags
       ctags.cnf (on MSDOS, MSWindows only)
              If any of these configuration files exist, each will be expected
              to contain a set of default options which are read in the order
              listed when ctags starts, but before the CTAGS environment
              variable is read or any command line options are read. This
              makes it possible to set up site-wide, personal or project-level
              defaults. It is possible to compile ctags to read an additional
              configuration file before any of those shown above, which will
              be indicated if the output produced by the --version option
              lists the "custom-conf" feature. Options appearing in the CTAGS
              environment variable or on the command line will override
              options specified in these files. Only options will be read from
              these files. Note that the option files are read in line-
              oriented mode in which spaces are significant (since shell
              quoting is not possible). Each line of the file is read as one
              command line parameter (as if it were quoted with single
              quotes). Therefore, use new lines to indicate separate command-
              line arguments.


       tags   The default tag file created by ctags.

       TAGS   The default tag file created by etags.


SEE ALSO
       The official Exuberant Ctags web site at:

              http://ctags.sourceforge.net

       Also ex(1), vi(1), elvis, or, better yet, vim, the official editor of
       ctags. For more information on vim, see the VIM Pages web site at:

              http://www.vim.org/



AUTHOR
       Darren Hiebert <dhiebert at users.sourceforge.net>
       http://DarrenHiebert.com/



MOTIVATION
       "Think ye at all times of rendering some service to every member of the
       human race."

       "All effort and exertion put forth by man from the fullness of his
       heart is worship, if it is prompted by the highest motives and the will
       to do service to humanity."

              -- From the Baha'i Writings



CREDITS
       This version of ctags was originally derived from and inspired by the
       ctags program by Steve Kirkendall <kirkenda@cs.pdx.edu> that comes with
       the Elvis vi clone (though virtually none of the original code
       remains).

       Credit is also due Bram Moolenaar <Bram@vim.org>, the author of vim,
       who has devoted so much of his time and energy both to developing the
       editor as a service to others, and to helping the orphans of Uganda.

       The section entitled "HOW TO USE WITH GNU EMACS" was shamelessly stolen
       from the info page for GNU etags.



Darren Hiebert                    Version 5.8                         CTAGS(1)
