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CTAGS(1)				 Exuberant Ctags				 CTAGS(1)

       ctags - Generate tag files for source code

       ctags [options] [file(s)]

       etags [options] [file(s)]

       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  lan-
       guages.	For  a	complete  list of supported languages, the names by which they are recog-
       nized, and the kinds of tags which are generated for each, see  the  --list-languages  and
       --list-kinds options.

       Unless the --language-force option is specified, the language of each source file is auto-
       matically 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

       [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.]

       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 inter-
	    preted 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 lan-
	    guage. 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 aris-
	    ing 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	parenthe-
	    sis-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 identi-
	    fier-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  identi-
	    fier  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. Specify-
	    ing -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

       -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

       -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  writ-
	    ten  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.

	    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.

	    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]

	    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 speci-
	    fied  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 pat-
	    terns  which  match  a given file name irrespective of its path, or match only a spe-
	    cific path. If appropriate support is available from the runtime library  of  your	C
	    compiler,  then  pattern  may  contain the usual shell wildcards (not regular expres-
	    sions) 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.

	    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)

	    number   Use only line numbers in the tag file  for  locating  tags.  This	has  four
		     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  cor-
		     respond  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 obso-
		     lete 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 gen-
		     erated  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.

	    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.  "exam-
		   ple.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  lan-
		   guage  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.

	    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.

	    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.

	    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 sup-
	    plied 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.

	    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 ter-
	    minating newline.  This option is quite esoteric and is empty by default. This option
	    must appear before the first file name.

	    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 back-
	    ward-compatibility with original vi(1) implementations). The default level is 2. This
	    option must appear before the first file name. [Ignored in etags mode]

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

	    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 skip-
	    ping  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  condi-
	    tional. This option is disabled by default.

	    Specifies a list of language-specific kinds of tags (or kinds) to include in the out-
	    put 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 (partic-
	    ular 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.

	    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.

	    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]ake-
	    file)").  If appropriate support is available from the runtime library of your C com-
	    piler, 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 wild-
	    cards 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; other-
	    wise, 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 "Make-
	    file", "makefile", or having the extension ".mak") to a language called "make", spec-
	    ify  "--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 key-
	    word "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.

	    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).

	    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  cur-
	    rent 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  lan-
	    guages, 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 pre-
	    viously  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.

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

	    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 abso-
	    lute 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.

	    Indicates  whether	symbolic  links (if supported) should be followed. When disabled,
	    symbolic links are ignored. This option is on by default.

	    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 imple-
	    mented 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]".

	    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.

	    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.

	    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  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.

	    The  /regexp/replacement/ pair define a regular expression replacement pattern, simi-
	    lar 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 gener-
	    ally 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  separa-
	    tor  character is used will have to be escaped with a backslash ('\') character wher-
	    ever 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 expres-
	    sion. 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 regu-
	    lar 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").

	    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 ignore-
	    case"). This option must appear before the first file name. [Ignored in etags mode]

	    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.

	    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.

	    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. Nor-
	    mally, ctags does not read command line arguments until after options are  read  from
	    the  configuration	files (see FILES, below) and the CTAGS environment variable. How-
	    ever, 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.

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

       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

       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  condition-

       In  general,  ctags tries to be smart about conditional preprocessor directives. If a pre-
       processor 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 {
	      union {
		  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 com-
       plicated 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  paren-
       theses 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  writ-
       ten as "operator<<").

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

       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:


       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

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

       kind	   Indicates  the  type,  or  kind, of tag. Its value is either one of the corre-
		   sponding 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.

		   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  look-
       ing like "struct:myStruct".

       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).

       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

       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.

       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.

       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

       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.

       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 specifi-
       cation  (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  gener-
       ated  for  the  function  definition.  It  will,  however be available for prototypes (e.g

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

       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 speci-
	       fies  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.

       /ctags.cnf (on MSDOS, MSWindows only)
       $HOME/ctags.cnf (on MSDOS, MSWindows only)
       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 pos-
	      sible).  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.

       The official Exuberant Ctags web site at:


       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:


       Darren Hiebert <dhiebert at users.sourceforge.net>

       "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

       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  virtu-
       ally 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)
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