Provided by: universal-ctags_5.9.20210829.0-1_amd64 
NAME
ctags - Generate tag files for source code
SYNOPSIS
ctags [<options>] [<source_file(s)>]
etags [<options>] [<source_file(s)>]
DESCRIPTION
The ctags and etags (see -e option) programs (hereinafter collectively referred to as
ctags, except where distinguished) generate an index (or "tag") file for a variety of
language objects found in source file(s). This tag file allows these items to be quickly
and easily located by a text editor or other utilities (client tools). 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 language objects found in a set of source 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. See the manual of your favorite editor about utilizing ctags
command and the tag index files in the editor.
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-full options.
This man page describes Universal Ctags, an implementation of ctags derived from Exuberant
Ctags. The major incompatible changes between Universal Ctags and Exuberant Ctags are
enumerated in ctags-incompatibilities(7).
One of the advantages of Exuberant Ctags is that it allows a user to define a new parser
from the command line. Extending this capability is one of the major features of Universal
Ctags. ctags-optlib(7) describes how the capability is extended.
Newly introduced experimental features are not explained here. If you are interested in
such features and ctags internals, visit https://docs.ctags.io/.
COMMAND LINE INTERFACE
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, =on, and =true are
considered synonyms for =yes, and that =0, =off, and =false 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.
<options> must precede the <source_file(s)> following the standard POSIX convention.
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.
Letters and names
Some options take one-letter flags as parameters (e.g. --kinds-<LANG> option). Specifying
just letters help a user create a complicated command line quickly. However, a command
line including sequences of one-letter flags becomes difficult to understand.
Universal Ctags accepts long-name flags in addition to such one-letter flags. The
long-name and one-letter flags can be mixed in an option parameter by surrounding each
long-name by braces. Thus, for an example, the following three notations for --kinds-C
option have the same meaning:
--kinds-C=+pLl
--kinds-C=+{prototype}{label}{local}
--kinds-C=+{prototype}L{local}
Note that braces may be meta characters in your shell. Put single quotes in such case.
--list-... options shows one-letter flags and associated long-name flags.
List options
Universal Ctags introduces many --list-... options that provide the internal data of
Universal Ctags (See "Listing Options"). Both users and client tools may use the data.
--with-list-header and --machinable options adjust the output of the most of --list-...
options.
The default setting (--with-list-header=yes and --machinable=no) is for using
interactively from a terminal. The header that explains the meaning of columns is simply
added to the output, and each column is aligned in all lines. The header line starts with
a hash ('#') character.
For scripting in a client tool, --with-list-header=no and --machinable=yes may be useful.
The header is not added to the output, and each column is separated by tab characters.
Note the order of columns will change in the future release. However, labels in the
header will not change. So by scanning the header, a client tool can find the index for
the target column.
OPTIONS
ctags has more options than listed here. Options starting with an underscore character,
such as --_echo=<msg>, are not listed here. They are experimental or for debugging
purpose.
Notation: <foo> is for a variable string foo, [ ... ] for optional, | for selection, and (
... ) for grouping. For example --foo[=(yes|no)]'' means ``--foo, -foo=yes, or -foo=no.
Input/Output File Options
--exclude=<pattern>
Add <pattern> to a list of excluded files and directories. This option may be
specified as many times as desired. For each file name considered by ctags, each
pattern specified using this option will be compared against both the complete path
(e.g. some/path/base.ext) and the base name (e.g. base.ext) of the file, thus
allowing patterns which match a given file name irrespective of its path, or match
only a specific path.
If appropriate support is available from the runtime library of your C compiler,
then pattern may contain the usual shell wildcards (not regular expressions) common
on Unix (be sure to quote the option parameter to protect the wildcards from being
expanded by the shell before being passed to ctags; also be aware that wildcards
can match the slash character, '/'). You can determine if shell wildcards are
available on your platform by examining the output of the --list-features 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 names of common
hidden and system files, patterns for binary files, and directories for which it is
generally not desirable to descend while processing the --recurse option. To see
the list of built-in exclude patterns, use --list-excludes.
See also the description for --exclude-exception= option.
--exclude-exception=<pattern>
Add <pattern> to a list of included files and directories. The pattern affects the
files and directories that are excluded by the pattern specified with --exclude=
option.
For an example, you want ctags to ignore all files under foo directory except
foo/main.c, use the following command line: --exclude=foo/*
--exclude-exception=foo/main.c.
--filter[=(yes|no)]
Makes ctags 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 --sort 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.
--filter-terminator=<string>
Specifies a <string> to print to standard output following the tags for each file
name parsed when the --filter option is enabled. This may permit an application
reading the output of ctags to determine when the output for each file is finished.
Note that if the file name read is a directory and --recurse is enabled, this
string will be printed only 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.
--links[=(yes|no)]
Indicates whether symbolic links (if supported) should be followed. When disabled,
symbolic links are ignored. This option is on by default.
--maxdepth=<N>
Limits the depth of directory recursion enabled with the --recurse (-R) option.
--recurse[=(yes|no)]
Recurse into directories encountered in the list of supplied files.
If the list of supplied files is empty and no file list is specified with the -L
option, then the current directory (i.e. '.') is assumed. Symbolic links are
followed by default (See --links option). If you don't like these behaviors, either
explicitly specify the files or pipe the output of find(1) into "ctags -L -"
instead. See, also, the --exclude and --maxdepth to limit recursion.
Note: This option is not supported on all platforms at present. It is available if
the output of the --help option includes this option.
-R Equivalent to --recurse.
-L <file>
Read from <file> a list of file names for which tags should be generated.
If file is specified as '-', then file names are read from standard input. File
names read using this option are processed following file names appearing on the
command line. Options are also accepted in this input. If this option is specified
more than once, only the last will apply.
Note: file is read in line-oriented mode, where a new line is the only delimiter
and non-trailing white space is considered significant, in order that file names
containing spaces may be supplied (however, trailing white space is stripped from
lines); this can affect how options are parsed if included in the input.
--append[=(yes|no)]
Indicates whether tags generated from the specified files should be appended to
those already present in the tag file or should replace them. This option is no by
default.
-a Equivalent to --append.
-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 tags are
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 "-f ./-ugly".
This option must appear before the first file name. If this option is specified
more than once, only the last will apply.
-o <tagfile>
Equivalent to "-f tagfile".
Output Format Options
--format=(1|2)
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. [Ignored in etags mode]
--output-format=(u-ctags|e-ctags|etags|xref|json)
Specify the output format. The default is u-ctags. See tags(5) for u-ctags and
e-ctags. See -e for etags, and -x for xref. json format is available only if the
ctags executable is built with libjansson. See ctags-client-tools(7) for more
about json format.
-e Same as --output-format=etags. 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.
-x Same as --output-format=xref. 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 --kinds-c=f file"), or generating a list
of all externally visible global variables located in a source file (e.g. "ctags -x
--kinds-c=v --extras=-F file").
--sort=(yes|no|foldcase)
Indicates whether the tag file should be sorted on the tag name (default is yes).
Note that the original vi(1) required sorted tags. The foldcase value specifies
case insensitive (or case-folded) sorting. Fast binary searches of tag files
sorted with case-folding will require special support from tools using tag files,
such as that found in the ctags readtags library, or Vim version 6.2 or higher
(using "set ignorecase"). [Ignored in etags mode]
-u Equivalent to --sort=no (i.e. "unsorted").
--etags-include=<file>
Include a reference to <file> in the tag file. This option may be specified as many
times as desired. This supports Emacs' capability to use a tag file which includes
other tag files. [Available only in etags mode]
--input-encoding=<encoding>
Specifies the <encoding> of the input files. If this option is specified,
Universal Ctags converts the input from this encoding to the encoding specified by
--output-encoding=encoding.
--input-encoding-<LANG>=<encoding>
Specifies a specific input <encoding> for <LANG>. It overrides the global default
value given with --input-encoding.
--output-encoding=<encoding>
Specifies the <encoding> of the tags file. Universal Ctags converts the encoding
of input files from the encoding specified by --input-encoding=<encoding> to this
encoding.
In addition <encoding> is specified at the top the tags file as the value for the
TAG_FILE_ENCODING pseudo-tag. The default value of <encoding> is UTF-8.
Language Selection and Mapping Options
--language-force=(<language>|auto)
By default, ctags automatically selects the language of a source file, ignoring
those files whose language cannot be determined (see "Determining file language").
This option forces the specified language (case-insensitive; either built-in or
user-defined) to be used for every supplied file instead of automatically selecting
the language based upon its extension.
In addition, the special value auto indicates that the language should be
automatically selected (which effectively disables this option).
--languages=[+|-](<list>|all)
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 (the current settings of enabled/disabled languages managed in ctags
internally) 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 the most of
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 list of the all (built-in and user-defined) language
names.
Note --languages= option works cumulative way; the option can be specified with
different arguments multiple times in a command line.
--alias-<LANG>=[+|-](<pattern>|default)
Adds ('+') or removes ('-') an alias <pattern> to a language specified with <LANG>.
ctags refers to the alias pattern in "Determining file language" stage.
The parameter <pattern> is not a list. Use this option multiple times in a command
line to add or remove multiple alias patterns.
To restore the default language aliases, specify default.
Using all for <LANG> has meaning in following two cases:
--alias-all=
This clears aliases setting of all languages.
--alias-all=default
This restores the default languages aliases for all languages.
--guess-language-eagerly
Looks into the file contents for heuristically guessing the proper language parser.
See "Determining file language".
-G Equivalent to --guess-language-eagerly.
--langmap=<map>[,<map>[...]]
Controls how file names are mapped to languages (see the --list-maps option). Each
comma-separated <map> consists of the language name (either a built-in or
user-defined language), a colon, and a list of file extensions and/or file name
patterns. A file extension is specified by preceding the extension with a period
(e.g. .c). A file name pattern is specified by enclosing the pattern in parentheses
(e.g. ([Mm]akefile)).
If appropriate support is available from the runtime library of your C compiler,
then the file name pattern may contain the usual shell wildcards common on Unix (be
sure to quote the option parameter to protect the wildcards from being expanded by
the shell before being passed to ctags). You can determine if shell wildcards are
available on your platform by examining the output of the --list-features 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 with --langmap option, it will first be unmapped from
any other languages. (--map-<LANG> option provides more fine-grained control.)
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 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 name patterns are tested before file extensions when inferring the
language of a file. This order of Universal Ctags is different from Exuberant
Ctags. See ctags-incompatibilities(7) for the background of this incompatible
change.
--map-<LANG>=[+|-]<extension>|<pattern>
This option provides the way to control mapping(s) of file names to languages in a
more fine-grained way than --langmap option.
In ctags, more than one language can map to a file name <pattern> or file
<extension> (N:1 map). Alternatively, --langmap option handle only 1:1 map, only
one language mapping to one file name <pattern> or file <extension>. A typical N:1
map is seen in C++ and ObjectiveC language; both languages have a map to .h as a
file extension.
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)). A prefixed plus ('+') sign is for adding, and minus ('-') is for
removing. No prefix means replacing the map of <LANG>.
Unlike --langmap, <extension> (or <pattern>) is not a list. --map-<LANG> takes one
extension (or pattern). However, the option can be specified with different
arguments multiple times in a command line.
Tags File Contents Options
See "TAG ENTRIES" about fields, kinds, roles, and extras.
--excmd=(number|pattern|mix|combine)
Determines the type of EX command used to locate tags in the source file. [Ignored
in etags mode]
The valid values for type (either the entire word or the first letter is accepted)
are:
number Use only line numbers in the tag file for locating tags. This has four
advantages:
1. Significantly reduces the size of the resulting tag file.
2. Eliminates failures to find tags because the line defining the tag has
changed, causing the pattern match to fail (note that some editors, such
as vim, are able to recover in many such instances).
3. Eliminates finding identical matching, but incorrect, source lines (see
"BUGS").
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: -B, -F.
number type is ignored in Xref and JSON output formats. Use
--_xformat="...%n" for Xref output format, or --fields=+n-P for JSON output
format.
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. 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.
This was the default format generated by the original ctags and is,
therefore, retained as the default for this option.
combine
Concatenate the line number and pattern with a semicolon in between.
-n Equivalent to --excmd=number.
-N Equivalent to --excmd=pattern.
--extras=[+|-][<flags>|*]
Specifies whether to include extra tag entries for certain kinds of information.
See also "Extras" subsection to know what are extras.
The parameter <flags> is a set of one-letter flags (and/or long-name flags), each
representing one kind of extra tag entry to include in the tag file. If flags is
preceded 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. All entries are included if '*' is given.
This --extras= option is for controlling extras common in all languages (or
language-independent extras). Universal Ctags also supports language-specific
extras. (See "Language-specific fields and extras" about the concept). Use
--extras-<LANG>= option for controlling them.
--extras-(<LANG>|all)=[+|-][<flags>|*]
Specifies whether to include extra tag entries for certain kinds of information for
language <LANG>. Universal Ctags introduces language-specific extras. See "‐
Language-specific fields and extras" about the concept. This option is for
controlling them.
Specifies all as <LANG> to apply the parameter <flags> to all languages; all extras
are enabled with specifying '*' as the parameter flags. If specifying nothing as
the parameter flags (--extras-all=), all extras are disabled. These two
combinations are useful for testing.
Check the output of the --list-extras=<LANG> option for the extras of specific
language <LANG>.
--fields=[+|-][<flags>|*]
Specifies which language-independent fields are to be included in the tag entries.
Language-independent fields are extension fields which are common in all languages.
See "TAG FILE FORMAT" section, and "Extension fields" subsection, for details of
extension fields.
The parameter <flags> is a set of one-letter or long-name flags, each representing
one type of extension field to include. Each flag or group of flags 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 fields explicitly listed in
flags will be included in the output (i.e. overriding the default set). All fields
are included if '*' is given.
This option is ignored if the option --format=1 (legacy tag file format) has been
specified.
Use --fields-<LANG>= option for controlling language-specific fields.
--fields-(<LANG>|all)=[+|-][<flags>|*]
Specifies which language-specific fields are to be included in the tag entries.
Universal Ctags supports language-specific fields. (See "Language-specific fields
and extras" about the concept).
Specify all as <LANG> to apply the parameter <flags> to all languages; all fields
are enabled with specifying '*' as the parameter flags. If specifying nothing as
the parameter <flags> (i.e. --fields-all=), all fields are disabled. These two
combinations are useful for testing.
See the description of --fields=[+|-][<flags>|*] about <flags>.
Use --fields= option for controlling language-independent fields.
--kinds-(<LANG>|all)=[+|-](<kinds>|*)
Specifies a list of language-specific <kinds> of tags (or kinds) to include in the
output file for a particular language, where <LANG> is case-insensitive and is one
of the built-in language names (see the --list-languages option for a complete
list).
The parameter <kinds> is a group of one-letter or long-name 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-full 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).
Specify '*' as the parameter to include all kinds implemented in <LANG> in the
output. Furthermore if all is given as <LANG>, specification of the parameter kinds
affects all languages defined in ctags. Giving all makes sense only when '*' or 'F'
is given as the parameter kinds.
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
--kinds-c=+px-d; to include only tags for functions, use --kinds-c=f.
Some kinds of C and C++ languages are synchronized; enabling (or disabling) a kind
in one language enables the kind having the same one-letter and long-name in the
other language. See also the description of MASTER column of --list-kinds-full.
--pattern-length-limit=<N>
Truncate patterns of tag entries after <N> characters. Disable by setting to 0
(default is 96).
An input source file with long lines and multiple tag matches per line can generate
an excessively large tags file with an unconstrained pattern length. For example,
running ctags on a minified JavaScript source file often exhibits this behavior.
The truncation avoids cutting in the middle of a UTF-8 code point spanning multiple
bytes to prevent writing invalid byte sequences from valid input files. This
handling allows for an extra 3 bytes above the configured limit in the worse case
of a 4 byte code point starting right before the limit. Please also note that this
handling is fairly naive and fast, and although it is resistant against any input,
it requires a valid input to work properly; it is not guaranteed to work as the
user expects when dealing with partially invalid UTF-8 input. This also partially
affect non-UTF-8 input, if the byte sequence at the truncation length looks like a
multibyte UTF-8 sequence. This should however be rare, and in the worse case will
lead to including up to an extra 3 bytes above the limit.
--pseudo-tags=[+|-](<pseudo-tag>|*)
Enable/disable emitting pseudo-tag named <pseudo-tag>. If '*' is given,
enable/disable emitting all pseudo-tags.
--put-field-prefix
Put UCTAGS as prefix for the name of fields newly introduced in Universal Ctags.
Some fields are newly introduced in Universal Ctags and more will be introduced in
the future. Other tags generators may also introduce their specific fields.
In such a situation, there is a concern about conflicting field names; mixing tags
files generated by multiple tags generators including Universal Ctags is difficult.
This option provides a workaround for such station.
$ ctags --fields='{line}{end}' -o - hello.c
main hello.c /^main(int argc, char **argv)$/;" f line:3 end:6
$ ctags --put-field-prefix --fields='{line}{end}' -o - hello.c
main hello.c /^main(int argc, char **argv)$/;" f line:3 UCTAGSend:6
In the above example, the prefix is put to end field which is newly introduced in
Universal Ctags.
--roles-(<LANG>|all).(<kind>|all)=[+|-][<roles>|*]
Specifies a list of kind-specific roles of tags to include in the output file for a
particular language. <kind> specifies the kind where the <roles> are defined.
<LANG> specifies the language where the kind is defined. Each role in <roles> must
be surrounded by braces (e.g. {system} for a role named "system").
Like --kinds-<LANG> option, '+' is for adding the role to the list, and '-' is for
removing from the list. '*' is for including all roles of the kind to the list.
The option with no argument makes the list empty.
Both a one-letter flag or a long name flag surrounded by braces are acceptable for
specifying a kind (e.g. --roles-C.h=+{system}{local} or
--roles-C.{header}=+{system}{local}). '*' can be used for <KIND> only for
adding/removing all roles of all kinds in a language to/from the list (e.g.
--roles-C.*=* or --roles-C.*=).
all can be used for <LANG> only for adding/removing all roles of all kinds in all
languages to/from the list (e.g. --roles-all.*=* or --roles-all.*=).
--tag-relative=(yes|no|always|never)
Specifies how the file paths recorded in the tag file. The default is yes when
running in etags mode (see the -e option), no otherwise.
yes indicates that the file paths recorded in the tag file should be relative to
the directory containing the tag file unless the files supplied on the
command line are specified with absolute paths.
no indicates that the file paths recorded in the tag file should be relative to
the current directory unless the files supplied on the command line are
specified with absolute paths.
always indicates the recorded file paths should be relative even if source file
names are passed in with absolute paths.
never indicates the recorded file paths should be absolute even if source file
names are passed in with relative paths.
--use-slash-as-filename-separator[=(yes|no)]
Uses slash ('/') character as filename separators instead of backslash ('\')
character when printing input: field. The default is yes for the default "u-ctags"
output format, and no for the other formats.
This option is available on MS Windows only.
-B Use backward searching patterns (e.g. ?pattern?). [Ignored in etags mode]
-F Use forward searching patterns (e.g. /pattern/) (default). [Ignored in etags mode]
Option File Options
--options=<pathname>
Read additional options from file or directory.
ctags searches <pathname> in the optlib path list first. If ctags cannot find a
file or directory in the list, ctags reads a file or directory at the specified
<pathname>.
If a file is specified, it should contain one option per line. If a directory is
specified, files suffixed with .ctags under it are read in alphabetical order.
As a special case, if --options=NONE is specified as the first option on the
command line, preloading is disabled; the option will disable the automatic reading
of any configuration options from a file (see "FILES").
--options-maybe=<pathname>
Same as --options but doesn't cause an error if file (or directory) specified with
<pathname> doesn't exist.
--optlib-dir=[+]<directory>
Add an optlib <directory> to or reset the optlib path list. By default, the optlib
path list is empty.
optlib Options
See ctags-optlib(7) for details of each option.
--kinddef-<LANG>=<letter>,<name>,<description>
Define a kind for <LANG>. Don't be confused this with --kinds-<LANG>.
--langdef=<name>
Defines a new user-defined language, <name>, to be parsed with regular expressions.
--mline-regex-<LANG>=/<line_pattern>/<name_pattern>/<kind-spec>/[<flags>]
Define multi-line regular expression for locating tags in specific language.
--regex-<LANG>=/<line_pattern>/<name_pattern>/<kind-spec>/[<flags>]
Define single-line regular expression for locating tags in specific language.
Language Specific Options
--if0[=(yes|no)]
Indicates a preference as to whether code within an "#if 0" branch of a
preprocessor conditional should be examined for non-macro tags (macro tags are
always included). Because the intent of this construct is to disable code, the
default value of this option is no (disabled).
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.
--line-directives[=(yes|no)]
Specifies whether #line directives should be recognized. These are present in the
output of a preprocessor and contain the line number, and possibly the file name,
of the original source file(s) from which the preprocessor output file was
generated. This option is off by default.
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).
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.
-D <macro>=<definition>
Defines a C preprocessor <macro>. This emulates the behavior of the corresponding
gcc option. All types of macros are supported, including the ones with parameters
and variable arguments. Stringification, token pasting and recursive macro
expansion are also supported. This extends the function provided by -I option.
-h (<list>|default)
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 particular kinds of tags are
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 '+', then the extensions in the list will be
appended to the current list; otherwise, the list will replace the current list.
See, also, the fileScope/F flag of --extras 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 "Determining file language", above), you will also need to
use either the --map-<LANG>, --langmap or --language-force option.
-I <identifier-list>
Specifies a <identifier-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 (i.e. "-I FOO+"), ctags will also
ignore any parenthesis-enclosed argument list which may immediately follow the
identifier in the source files. See the example of "-I MODULE_VERSION+" below.
If two identifiers are separated with the '=' character (i.e. -I FOO=BAR), 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. See the example of "-I CLASS=class" below.
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 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"). 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$")
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".
--param-<LANG>:<name>=<argument>
Set a <LANG> specific parameter, a parameter specific to the <LANG>.
Available parameters can be listed with --list-params.
Listing Options
--list-aliases[=(<language>|all)]
Lists the aliases for either the specified <language> or all languages, and then
exits. all is used as default value if the option argument is omitted. The
aliases are used when heuristically testing a language parser for a source file.
--list-excludes
Lists the current exclusion patterns used to exclude files.
--list-extras[=(<language>|all)]
Lists the extras recognized for either the specified <language> or all languages.
See "Extras" subsection to know what are extras. all is used as default value if
the option argument is omitted.
An extra can be enabled or disabled with --extras= for common extras in all
languages, or --extras-<LANG>= for the specified language. These option takes
one-letter flag or long-name flag as a parameter for specifying an extra.
The meaning of columns in output are as follows:
LETTER One-letter flag. '-' means the extra does not have one-letter flag.
NAME Long-name flag. The long-name is used in extras field.
ENABLED
Whether the extra is enabled or not. It takes yes or no.
LANGUAGE
The name of language if the extra is owned by a parser. NONE means the
extra is common in parsers.
DESCRIPTION
Human readable description for the extra.
--list-features
Lists the compiled features.
--list-fields[=(<language>|all)]
Lists the fields recognized for either the specified <language> or all languages.
See "Extension fields" subsection to know what are fields. all is used as default
value if the option argument is omitted.
The meaning of columns are as follows:
LETTER One-letter flag. '-' means the field does not have one-letter flag.
NAME Long-name of field.
ENABLED
Whether the field is enabled or not. It takes yes or no.
LANGUAGE
The name of language if the field is owned by a parser. NONE means that the
field is a language-independent field which is common in all languages.
JSTYPE JSON type used in printing the value of field when --output-format=json is
specified. See ctags-client-tools(7).
FIXED Whether this field can be disabled or not in tags output.
Some fields are printed always in tags output. They have yes as the value
for this column.
Unlike the tag output mode, JSON output mode allows disabling any fields.
OP How this field can be accessed from optscript code. This field is for
Universal Ctags developers.
DESCRIPTION
Human readable description for the field.
--list-kinds[=(<language>|all)]
Subset of --list-kinds-full. This option is kept for backward-compatibility with
Exuberant Ctags.
This option prints only LETTER, DESCRIPTION, and ENABLED fields of
--list-kinds-full output. However, the presentation of ENABLED column is different
from that of --list-kinds-full option; [off] follows after description if the kind
is disabled, and nothing follows if enabled. The most of all kinds are enabled
by default.
The critical weakness of this option is that this option does not print the name of
kind. Universal Ctags introduces --list-kinds-full because it considers that names
are important.
This option does not work with --machinable nor --with-list-header.
--list-kinds-full[=(<language>|all)]
Lists the tag kinds recognized for either the specified <language> or all
languages, and then exits. See "Kinds" subsection to learn what kinds are. all is
used as default value if the option argument is omitted.
Each kind of tag recorded in the tag file is represented by a one-letter flag, or a
long-name flag. They are also used to filter the tags placed into the output
through use of the --kinds-<LANG> option.
The meaning of columns are as follows:
LANGUAGE
The name of language having the kind.
LETTER One-letter flag. This must be unique in a language.
NAME The long-name flag of the kind. This can be used as the alternative to the
one-letter flag described above. If enabling K field with --fields=+K, ctags
uses long-names instead of one-letters in tags output. To enable/disable a
kind with --kinds-<LANG> option, long-name surrounded by braces instead of
one-letter. See "Letters and names" for details. This must be unique in a
language.
ENABLED
Whether the kind is enabled or not. It takes yes or no.
REFONLY
Whether the kind is specialized for reference tagging or not. If the column
is yes, the kind is for reference tagging, and it is never used for
definition tagging. See also "TAG ENTRIES".
NROLES The number of roles this kind has. See also "Roles".
MASTER The master parser controlling enablement of the kind. A kind belongs to a
language (owner) in Universal Ctags; enabling and disabling a kind in a
language has no effect on a kind in another language even if both kinds has
the same one-letter flag and/or the same long-name flag. In other words, the
namespace of kinds are separated by language.
However, Exuberant Ctags does not separate the kinds of C and C++.
Enabling/disabling kindX in C language enables/disables a kind in C++
language having the same long-name flag with kindX. To emulate this behavior
in Universal Ctags, a concept named master parser is introduced.
Enabling/disabling some kinds are synchronized under the control of a master
language.
$ ctags --kinds-C=+'{local}' --list-kinds-full \
| grep -E '^(#|C\+\+ .* local)'
#LANGUAGE LETTER NAME ENABLED REFONLY NROLES MASTER DESCRIPTION
C++ l local yes no 0 C local variables
$ ctags --kinds-C=-'{local}' --list-kinds-full \
| grep -E '^(#|C\+\+ .* local)'
#LANGUAGE LETTER NAME ENABLED REFONLY NROLES MASTER DESCRIPTION
C++ l local no no 0 C local variables
You see ENABLED field of local kind of C++ language is changed Though local
kind of C language is enabled/disabled. If you swap the languages, you see
the same result.
DESCRIPTION
Human readable description for the kind.
--list-languages
Lists the names of the languages understood by ctags, and then exits. These
language names are case insensitive and may be used in many other options like
--language-force, --languages, --kinds-<LANG>, --regex-<LANG>, and so on.
Each language listed is disabled if followed by [disabled]. To use the parser for
such a language, specify the language as an argument of --languages=+ option.
--machinable and --with-list-header options are ignored if they are specified with
this option.
--list-map-extensions[=(<language>|all)]
Lists the file extensions which associate a file name with a language for either
the specified <language> or all languages, and then exits. all is used as default
value if the option argument is omitted.
--list-map-patterns[=(<language>|all)]
Lists the file name patterns which associate a file name with a language for either
the specified <language> or all languages, and then exits. all is used as default
value if the option argument is omitted.
--list-maps[=(<language>|all)]
Lists file name patterns and the file extensions which associate a file name with a
language for either the specified <language> or all languages, and then exits. all
is used as default value if the option argument is omitted.
To list the file extensions or file name patterns individually, use
--list-map-extensions or --list-map-patterns option. See the --langmap option, and
"Determining file language", above.
This option does not work with --machinable nor --with-list-header.
--list-mline-regex-flags
Output list of flags which can be used in a multiline regex parser definition. See
ctags-optlib(7).
--list-params[=(<language>|all)]
Lists the parameters for either the specified <language> or all languages, and then
exits. all is used as default value if the option argument is omitted.
--list-pseudo-tags
Output list of pseudo-tags.
--list-regex-flags
Lists the flags that can be used in --regex-<LANG> option. See ctags-optlib(7).
--list-roles[=(<language>|all)[.(<kind-specs>|*)]]
List the roles for either the specified <language> or all languages. all is used
as default value if the option argument is omitted.
If the parameter <kindspecs> is given after the parameter <language> or all with
concatenating with '.', list only roles defined in the kinds. Both one-letter flags
and long name flags surrounded by braces are acceptable as the parameter
<kindspecs>.
The meaning of columns are as follows:
LANGUAGE
The name of language having the role.
KIND(L/N)
The one-letter flag and the long-name flag of kind having the role.
NAME The long-name flag of the role.
ENABLED
Whether the kind is enabled or not. It takes yes or no.
DESCRIPTION
Human readable description for the role.
--list-subparsers[=(<baselang>|all)]
Lists the subparsers for a base language for either the specified <baselang> or all
languages, and then exits. all is used as default value if the option argument is
omitted.
--machinable[=(yes|no)]
Use tab character as separators for --list- option output. It may be suitable for
scripting. See "List options" for considered use cases. Disabled by default.
--with-list-header[=(yes|no)]
Print headers describing columns in --list- option output. See also "List
options".
Miscellaneous Options
--help Prints to standard output a detailed usage description, and then exits.
-? Equivalent to --help.
--help-full
Prints to standard output a detailed usage description including experimental
features, and then exits. Visit https://docs.ctags.io/ for information about the
latest exciting experimental features.
--license
Prints a summary of the software license to standard output, and then exits.
--print-language
Just prints the language parsers for specified source files, and then exits.
--quiet[=(yes|no)]
Write fewer messages (default is no).
--totals[=(yes|no|extra)]
Prints statistics about the source files read and the tag file written during the
current invocation of ctags. This option is no by default.
The extra value prints parser specific statistics for parsers gathering such
information.
--verbose[=(yes|no)]
Enable verbose mode. This prints out information on option processing and a brief
message describing what action is being taken for each file considered by ctags.
Normally, ctags does not read command line arguments until after options are read
from the configuration files (see "FILES", below). 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.
-V Equivalent to --verbose.
--version
Prints a version identifier for ctags to standard output, and then exits. This is
guaranteed to always contain the string "Universal Ctags".
Obsoleted Options
These options are kept for backward-compatibility with Exuberant Ctags.
-w This option is silently ignored for backward-compatibility with the ctags of SVR4
Unix.
--file-scope[=(yes|no)]
This options is removed. Use --extras=[+|-]F or --extras=[+|-]{fileScope} instead.
--extra=[+|-][<flags>|*]
Equivalent to --extras=[+|-][<flags>|*], which was introduced to make the option
naming convention align to the other options like --kinds-<LANG>= and --fields=.
--<LANG>-kinds=[+|-](<kinds>|*)
This option is obsolete. Use --kinds-<LANG>=... instead.
OPERATIONAL DETAILS
As ctags considers each source file name in turn, it tries to determine the language of
the file by applying tests described in "Determining file language".
If a language was identified, the file is opened and then the appropriate language parser
is called to operate on the currently open file. The parser parses through the file and
adds an entry to the tag file for each language object it is written to handle. See "TAG
FILE FORMAT", below, for details on these entries.
Notes for C/C++ Parser
This implementation of ctags imposes no formatting requirements on C code as do legacy
implementations. Older implementations of ctags tended to rely upon certain formatting
assumptions in order to help it resolve coding dilemmas caused by preprocessor
conditionals.
In general, ctags tries to be smart about conditional preprocessor directives. If a
preprocessor conditional is encountered within a statement which defines a tag, ctags
follows only the first branch of that conditional (except in the special case of #if 0, in
which case it follows only the last branch). The reason for this is that failing to pursue
only one branch can result in ambiguous syntax, as in the following example:
#ifdef TWO_ALTERNATIVES
struct {
#else
union {
#endif
short a;
long b;
}
Both branches cannot be followed, or braces become unbalanced and ctags would be unable to
make sense of the syntax.
If the application of this heuristic fails to properly parse a file, generally due to
complicated and inconsistent pairing within the conditionals, ctags will retry the file
using a different heuristic which does not selectively follow conditional preprocessor
branches, but instead falls back to relying upon a closing brace ('}') in column 1 as
indicating the end of a block once any brace imbalance results from following a #if
conditional branch.
ctags will also try to specially handle arguments lists enclosed in double sets of
parentheses in order to accept the following conditional construct:
extern void foo __ARGS((int one, char two));
Any name immediately preceding the '((' will be automatically ignored and the previous
name will be used.
C++ operator definitions are specially handled. In order for consistency with all types of
operators (overloaded and conversion), the operator name in the tag file will always be
preceded by the string "operator " (i.e. even if the actual operator definition was
written as "operator<<").
After creating or appending to the tag file, it is sorted by the tag name, removing
identical tag lines.
Determining file language
File name mapping
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 displayed using the --list-maps option and may be changed
using the --langmap or --map-<LANG> options.
If the name of a file is not mapped to a language, ctags tries to heuristically guess the
language for the file by inspecting its content.
All files that have no file name mapping and no guessed parser are ignored. This permits
running ctags on all files in either a single directory (e.g. "ctags *"), or on all files
in an entire source directory tree (e.g. "ctags -R"), since only those files whose names
are mapped to languages will be scanned.
An extension may be mapped to multiple parsers. For example, .h are mapped to C++, C and
ObjectiveC. These mappings can cause issues. ctags tries to select the proper parser for
the source file by applying heuristics to its content, however it is not perfect. In case
of issues one can use --language-force=<language>, --langmap=<map>[,<map>[...]], or the
--map-<LANG>=[+|-]<extension>|<pattern> options. (Some of the heuristics are applied
whether --guess-language-eagerly is given or not.)
Heuristically guessing
If ctags cannot select a parser from the mapping of file names, various heuristic tests
are conducted to determine the language:
template file name testing
If the file name has an .in extension, ctags applies the mapping to the file name
without the extension. For example, config.h is tested for a file named
config.h.in.
interpreter testing
The first line of the file is checked to see if the file is a #! script for a
recognized language. ctags looks for a parser having the same name.
If ctags finds no such parser, ctags looks for the name in alias lists. For
example, consider if the first line is #!/bin/sh. Though ctags has a "shell"
parser, it doesn't have a "sh" parser. However, sh is listed as an alias for shell,
therefore ctags selects the "shell" parser for the file.
An exception is env. If env is specified (for example "#!/usr/bin/env python"),
ctags reads more lines to find real interpreter specification.
To display the list of aliases, use --list-aliases option. To add an item to the
list or to remove an item from the list, use the --alias-<LANG>=+<pattern> or
--alias-<LANG>=-<pattern> option respectively.
zsh autoload tag testing
If the first line starts with #compdef or #autoload, ctags regards the line as
"zsh".
emacs mode at the first line testing
The Emacs editor has multiple editing modes specialized for programming languages.
Emacs can recognize a marker called modeline in a file and utilize the marker for
the mode selection. This heuristic test does the same as what Emacs does.
ctags treats MODE as a name of interpreter and applies the same rule of
"interpreter" testing if the first line has one of the following patterns:
-*- mode: MODE -*-
or
-*- MODE -*-
emacs mode at the EOF testing
Emacs editor recognizes another marker at the end of file as a mode specifier. This
heuristic test does the same as what Emacs does.
ctags treats MODE as a name of an interpreter and applies the same rule of
"interpreter" heuristic testing, if the lines at the tail of the file have the
following pattern:
Local Variables:
...
mode: MODE
...
End:
3000 characters are sought from the end of file to find the pattern.
vim modeline testing
Like the modeline of the Emacs editor, Vim editor has the same concept. ctags
treats TYPE as a name of interpreter and applies the same rule of "interpreter"
heuristic testing if the last 5 lines of the file have one of the following
patterns:
filetype=TYPE
or
ft=TYPE
PHP marker testing
If the first line is started with <?php, ctags regards the line as "php".
Looking into the file contents is a more expensive operation than file name matching. So
ctags runs the testings in limited conditions. "interpreter" testing is enabled only when
a file is an executable or the --guess-language-eagerly (-G in short) option is given. The
other heuristic tests are enabled only when -G option is given.
The --print-language option can be used just to print the results of parser selections for
given files instead of generating a tags file.
Examples:
$ ctags --print-language config.h.in input.m input.unknown
config.h.in: C++
input.m: MatLab
input.unknown: NONE
NONE means that ctags does not select any parser for the file.
TAG FILE FORMAT
This section describes the tag file format briefly. See tags(5) and ctags-client-tools(7)
for more details.
When not running in etags mode, each entry in the tag file consists of a separate line,
each looking like this, called regular tags, in the most general case:
<tag_name><TAB><file_name><TAB><ex_cmd>;"<TAB><extension_fields>
The fields and separators of these lines are specified as follows:
1. <tag_name>: tag name
2. <TAB>: single tab character
3. <file_name>: name of the file in which the object associated with the tag is located
4. <TAB>: single tab character
5. <ex_cmd>: EX command used to locate the tag within the file; generally a search
pattern (either /pattern/ or ?pattern?) or line number (see --excmd=<type> option).
6. ;"<TAB><extension_fields>: a set of extension fields. See "Extension fields" for
more details.
Tag file format 2 (see --format) extends the EX command to include the extension
fields 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, called pseudo tags, are written into the tag file for internal
purposes.
!_TAG_FILE_FORMAT 2 /extended format; --format=1 will not append ;" to lines/
!_TAG_FILE_SORTED 1 /0=unsorted, 1=sorted, 2=foldcase/
...
--pseudo-tags=[+|-](<pseudo-tag>|*) option enables or disables emitting pseudo-tags.
See the output of "ctags --list-pseudo-tags" for the list of the kinds. See also tags(5)
and ctags-client-tools(7) for more details of the pseudo tags.
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=(yes|no|always|never) option for how this behavior
can be modified.
TAG ENTRIES
A tag is an index for a language object. The concept of a tag and related items in
Exuberant Ctags are refined and extended in Universal Ctags.
A tag is categorized into definition tags or reference tags. In general, Exuberant Ctags
only tags definitions of language objects: places where newly named language objects are
introduced. Universal Ctags, on the other hand, can also tag references of language
objects: places where named language objects are used. However, support for generating
reference tags is new and limited to specific areas of specific languages in the current
version.
Extension fields
A tag can record various information, called extension fields.
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.
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.
--fields=[+|-][<flags>|*] and --fields-(<LANG>|all)=[+|-][<flags>|*] options specifies
which available extension fields are to be included in the tag entries.
See the output of "ctags --list-fields" for the list of extension fields. The essential
fields are name, input, pattern, and line. The meaning of major fields is as follows
(long-name flag/one-letter flag):
access/a
Indicates the visibility of this class member, where value is specific to the
language.
end/e Indicates the line number of the end lines of the language object.
extras/E
Extra tag type information. See "Extras" for details.
file/f Indicates that the tag has file-limited visibility. This key has no corresponding
value. Enabled by default.
implementation/m
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/i
When present, value is a comma-separated list of classes from which this class is
derived (i.e. inherits from).
input/F
The name of source file where name is defined or referenced.
k Kind of tag as one-letter. Enabled by default. This field has no long-name. See
also kind/z flag.
K Kind of tag as long-name. This field has no long-name. See also kind/z flag.
kind/z Include the kind: key in kind field. See also k and K flags.
language/l
Language of source file containing tag
line/n The line number where name is defined or referenced in input.
name/N The name of language objects.
nth/o The order in the parent scope. (i.e. 4th parameter in the function).
pattern/P
Can be used to search the name in input
roles/r
Roles assigned to the tag. See "Roles" for more details.
s Scope of tag definition. Enabled by default. This field has no long-name. See
also scope/Z flag.
scope/Z
Prepend the scope: key to scope (s) field. See also s flag.
scopeKind/p
Kind of scope as long-name
signature/S
When present, value is a language-dependent representation of the signature of a
routine (e.g. prototype or parameter list). 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.
typeref/t
Type and name of a variable, typedef, or return type of callable like function as
typeref: field. Enabled by default.
Kinds
kind is a field which represents the kind of language object specified by a tag. Kinds
used and defined are very different between parsers. For example, C language defines
macro, function, variable, typedef, etc.
--kinds-(<LANG>|all)=[+|-](<kinds>|*) option specifies a list of language-specific kinds
of tags (or kinds) to include in the output file for a particular language.
See the output of "ctags --list-kinds-full" for the complete list of the kinds.
Its value is either one of the corresponding one-letter flags or a long-name flag. 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 as follows.
$ ctags -o - kinds.c
foo kinds.c /^int foo() {$/;" f typeref:typename:int
$ ctags --fields=+k -o - kinds.c
foo kinds.c /^int foo() {$/;" f typeref:typename:int
$ ctags --fields=+K -o - kinds.c
foo kinds.c /^int foo() {$/;" function typeref:typename:int
$ ctags --fields=+z -o - kinds.c
foo kinds.c /^int foo() {$/;" kind:f typeref:typename:int
$ ctags --fields=+zK -o - kinds.c
foo kinds.c /^int foo() {$/;" kind:function typeref:typename:int
Roles
Role is a newly introduced concept in Universal Ctags. Role is a concept associated with
reference tags, and is not implemented widely yet.
As described previously in "Kinds", the kind field represents the type of language object
specified with a tag, such as a function vs. a variable. Specific kinds are defined for
reference tags, such as the C++ kind header for header file, or Java kind package for
package statements. For such reference kinds, a roles field can be added to distinguish
the role of the reference kind. In other words, the kind field identifies the what of the
language object, whereas the roles field identifies the how of a referenced language
object. Roles are only used with specific kinds.
For a definition tag, this field takes def as a value.
For example, Baz is tagged as a reference tag with kind package and with role imported
with the following code.
package Bar;
import Baz;
class Foo {
// ...
}
$ ctags --fields=+KEr -uo - roles.java
Bar roles.java /^package Bar;$/;" package roles:def
Foo roles.java /^class Foo {$/;" class roles:def
$ ctags --fields=+EKr --extras=+r -uo - roles.java
Bar roles.java /^package Bar;$/;" package roles:def
Baz roles.java /^import Baz;$/;" package roles:imported extras:reference
Foo roles.java /^class Foo {$/;" class roles:def
--roles-(<LANG>|all).(<kind>|all)=[+|-][<roles>|*] option specifies a list of
kind-specific roles of tags to include in the output file for a particular language.
Inquire the output of "ctags --list-roles" for the list of roles.
Extras
Generally, ctags tags only language objects appearing in source files, as is. In other
words, a value for a name: field should be found on the source file associated with the
name:. An extra type tag (extra) is for tagging a language object with a processed name,
or for tagging something not associated with a language object. A typical extra tag is
qualified, which tags a language object with a class-qualified or scope-qualified name.
--extras-(<LANG>|all)=[+|-][<flags>|*] option specifies whether to include extra tag
entries for certain kinds of information.
Inquire the output of ctags --list-extras for the list of extras. The meaning of major
extras is as follows (long-name flag/one-letter flag):
anonymous/none
Include an entry for the language object that has no name like lambda function.
This extra has no one-letter flag and is enabled by default.
The extra tag is useful as a placeholder to fill scope fields for language objects
defined in a language object with no name.
struct {
double x, y;
} p = { .x = 0.0, .y = 0.0 };
'x' and 'y' are the members of a structure. When filling the scope fields for them,
ctags has trouble because the struct where 'x' and 'y' belong to has no name. For
overcoming the trouble, ctags generates an anonymous extra tag for the struct and
fills the scope fields with the name of the extra tag.
$ ctags --fields=-f -uo - input.c
__anon9f26d2460108 input.c /^struct {$/;" s
x input.c /^ double x, y;$/;" m struct:__anon9f26d2460108
y input.c /^ double x, y;$/;" m struct:__anon9f26d2460108
p input.c /^} p = { .x = 0.0, .y = 0.0 };$/;" v typeref:struct:__anon9f26d2460108
The above tag output has __anon9f26d2460108 as an anonymous extra tag. The typeref
field of 'p' also receives the benefit of it.
fileScope/F
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 language objects with
static modifier of C language) should be included in the output. See also the -h
option.
This extra tag is enabled by default. Add --extras=-F option not to output tags
scoped only for a single-file. This is the replacement for --file-scope option of
Exuberant Ctags.
static int f() {
return 0;
}
int g() {
return 0;
}
$ ctags -uo - filescope.c
f filescope.c /^static int f() {$/;" f typeref:typename:int file:
g filescope.c /^int g() {$/;" f typeref:typename:int
$ ctags --extras=-F -uo - filescope.c
g filescope.c /^int g() {$/;" f typeref:typename:int
inputFile/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. This flag is the replacement for
--file-tags hidden option of Exuberant Ctags.
If the end: field is enabled, the end line number of the file can be attached to
the tag. (However, ctags omits the end: field if no newline is in the file like an
empty file.)
By default, ctags doesn't create the inputFile/f extra tag for the source file when
ctags doesn't find a parser for it. Enabling Unknown parser with
--languages=+Unknown forces ctags to create the extra tags for any source files.
The etags mode enables the Unknown parser implicitly.
pseudo/p
Include pseudo-tags. Enabled by default unless the tag file is written to standard
output. See ctags-client-tools(7) about the detail of pseudo-tags.
qualified/q
Include an extra class-qualified or namespace-qualified tag entry for each tag
which is a member of a class or a namespace.
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.
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++ and Perl, it is in the form class::member; for
Eiffel and Java, it is in the form class.member.
Note: Using backslash characters as separators forming qualified name in PHP.
However, in tags output of Universal Ctags, a backslash character in a name is
escaped with a backslash character. See tags(5) about the escaping.
The following example demonstrates the qualified extra tag.
class point {
double x;
};
For the above source file, ctags tags point and x by default. If the qualified
extra is enabled from the command line (--extras=+q), then point.x is also tagged
even though the string "point.x" is not in the source code.
$ ctags --fields=+K -uo - qualified.java
point qualified.java /^class point {$/;" class
x qualified.java /^ double x;$/;" field class:point
$ ctags --fields=+K --extras=+q -uo - qualified.java
point qualified.java /^class point {$/;" class
x qualified.java /^ double x;$/;" field class:point
point.x qualified.java /^ double x;$/;" field class:point
reference/r
Include reference tags. See "TAG ENTRIES" about reference tags.
The following example demonstrates the reference extra tag.
#include <stdio.h>
#include "utils.h"
#define X
#undef X
The roles:system or roles:local fields will be added depending on whether the
include file name begins with '<' or not.
"#define X" emits a definition tag. On the other hand "#undef X" emits a reference
tag.
$ ctags --fields=+EKr -uo - inc.c
X inc.c /^#define X$/;" macro file: roles:def extras:fileScope
$ ctags --fields=+EKr --extras=+r -uo - inc.c
stdio.h inc.c /^#include <stdio.h>/;" header roles:system extras:reference
utils.h inc.c /^#include "utils.h"/;" header roles:local extras:reference
X inc.c /^#define X$/;" macro file: roles:def extras:fileScope
X inc.c /^#undef X$/;" macro file: roles:undef extras:fileScope,reference
Language-specific fields and extras
Exuberant Ctags has the concept of fields and extras. They are common between parsers of
different languages. Universal Ctags extends this concept by providing language-specific
fields and extras.
HOW TO USE WITH VI
vi(1) will, by default, expect a tag file by the name tags in the current directory. Once
the tag file is built, the following commands exercise the tag indexing feature:
vi -t tag
Start vi and position the cursor at the file and line where tag is defined.
:ta tag
Find a tag.
Ctrl-] Find the tag under the cursor.
Ctrl-T Return to previous location before jump to tag (not widely implemented).
HOW TO USE WITH GNU EMACS
emacs(1) will, by default, expect a tag file by the name TAGS in the current directory.
Once the tag file is built, the following commands exercise the tag indexing feature:
M-x visit-tags-table <RET> FILE <RET>
Select the tag file, FILE, to use.
M-. [TAG] <RET>
Find the first definition of TAG. The default tag is the identifier under the
cursor.
M-* Pop back to where you previously invoked M-..
C-u M-.
Find the next definition for the last tag.
For more commands, see the Tags topic in the Emacs info document.
HOW TO USE WITH NEDIT
NEdit version 5.1 and later can handle the new extended tag file format (see --format).
• To make NEdit use the tag file, select "File->Load Tags File".
• To jump to the definition for a tag, highlight the word, then press Ctrl-D.
NEdit 5.1 can read multiple tag files from different directories. Setting the X resource
nedit.tagFile to the name of a tag file instructs NEdit to automatically load that tag
file at startup time.
CAVEATS
Because ctags is neither a preprocessor nor a compiler, use of preprocessor macros can
fool ctags into either missing tags or improperly generating inappropriate tags. Although
ctags has been designed to handle certain common cases, this is the single biggest cause
of reported problems. In particular, the use of preprocessor constructs which alter the
textual syntax of C can fool ctags. You can work around many such problems by using the -I
option.
Note that since ctags generates patterns for locating tags (see the --excmd option), it is
entirely possible that the wrong line may be found by your editor if there exists another
source line which is identical to the line containing the tag. The following example
demonstrates this condition:
int variable;
/* ... */
void foo(variable)
int variable;
{
/* ... */
}
Depending upon which editor you use and where in the code you happen to be, it is possible
that the search pattern may locate the local parameter declaration before it finds the
actual global variable definition, since the lines (and therefore their search patterns)
are identical.
This can be avoided by use of the --excmd=n option.
BUGS
ctags has more options than ls(1).
ctags assumes the input file is written in the correct grammar. Otherwise output of ctags
is undefined. In other words it has garbage in, garbage out (GIGO) feature.
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.
--kinds-c++=+p).
No qualified tags are generated for language objects inherited into a class.
ENVIRONMENT VARIABLES
TMPDIR On Unix-like hosts where mkstemp(3) 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
sort(1) utility of the operating system. If the sort(1) utility of the operating
system is being used, it will generally observe this variable also.
Note that if ctags is setuid, the value of TMPDIR will be ignored.
FILES
tags The default tag file created by ctags.
TAGS The default tag file created by etags.
$XDG_CONFIG_HOME/ctags/*.ctags, or $HOME/.config/ctags/*.ctags if $XDG_CONFIG_HOME is not
defined (on other than MS Windows)
$HOME/.ctags.d/*.ctags
$HOMEDRIVE$HOMEPATH/ctags.d/*.ctags (on MS Windows only)
.ctags.d/*.ctags
ctags.d/*.ctags
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 any
command line options are read. This makes it possible to set up 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 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) but spaces at the beginning of a line
are ignored. 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.
A line starting with '#' is treated as a comment.
*.ctags files in a directory are loaded in alphabetical order.
SEE ALSO
See ctags-optlib(7) for defining (or extending) a parser in a configuration file.
See tags(5) for the format of tag files.
See ctags-incompatibilities(7) about known incompatible changes with Exuberant Ctags.
See ctags-client-tools(7) if you are interested in writing a tool for processing tags
files.
See ctags-lang-python(7) about python input specific notes.
See readtags(1) about a client tool for binary searching a name in a sorted tags file.
The official Universal Ctags web site at: https://ctags.io/
Also ex(1), vi(1), elvis(1), or, better yet, vim(1), the official editor of ctags. For
more information on vim(1), see the Vim web site at: https://www.vim.org/
AUTHOR
Universal Ctags project https://ctags.io/
Darren Hiebert <dhiebert@users.sourceforge.net> http://DarrenHiebert.com/
MOTIVATION
"Think ye at all times of rendering some service to every member of the human race."
"All effort and exertion put forth by man from the fullness of his heart is worship, if it
is prompted by the highest motives and the will to do service to humanity."
-- From the Baha'i Writings
CREDITS
This version of ctags (Universal Ctags) derived from the repository, known as
fishman-ctags, started by Reza Jelveh.
The fishman-ctags was derived from Exuberant Ctags.
Some parsers are taken from tagmanager of the Geany (https://www.geany.org/) project.
Exuberant Ctags was originally derived from and inspired by the ctags program by Steve
Kirkendall <kirkenda@cs.pdx.edu> that comes with the Elvis vi clone (though virtually none
of the original code remains).
Credit is also due Bram Moolenaar <Bram@vim.org>, the author of vim, who has devoted so
much of his time and energy both to developing the editor as a service to others, and to
helping the orphans of Uganda.
The section entitled "HOW TO USE WITH GNU EMACS" was shamelessly stolen from the info page
for GNU etags.