Provided by: arduino-ctags_5.8-arduino11-2_amd64 bug


       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
       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.


       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

       [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
            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
            "".  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

       -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
            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.

            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
            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.

            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
                     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.

            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.

            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
            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.

            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.

            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]

            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
            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.

            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

            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]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

            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
            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.

            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
            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.

            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
            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]".

            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,
            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

               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").

            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

            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.
            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.

            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

       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 {
              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
       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.


       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
                   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.

                   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".


       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
       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

       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
               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.


       /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
              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.


       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>


       "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  <>  that  comes  with  the  Elvis  vi  clone  (though
       virtually none of the original code remains).

       Credit  is  also  due Bram Moolenaar <>, 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.