Provided by: universal-ctags_0+git20181215-2_amd64 
NAME
ctags-universal - Generate tag files for source code
SYNOPSIS
ctags-universal [options] [source_file(s)]
etags [options] [source_file(s)]
DESCRIPTION
The ctags-universal and etags programs (hereinafter collectively referred to as ctags-universal, 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-universal 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-universal command and the tag index files in the
editor.
ctags-universal 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-universal internals, visit http://docs.ctags.io/en/latest/.
SOURCE FILES
Unless the --language-force option is specified, the language of each source file is automatically
selected based upon a mapping of file names to languages. The mappings in effect for each language may be
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-universal tries to heuristically guess the
language for the file by inspecting its content. See "Determining file language".
All files that have no file name mapping and no guessed parser are ignored. This permits running
ctags-universal on all files in either a single directory (e.g. "ctags-universal *"), or on all files in
an entire source directory tree (e.g. "ctags-universal -R"), since only those files whose names are
mapped to languages will be scanned.
The same extensions are mapped to multiple parsers. For example, ".h" are mapped to C++, C and
ObjectiveC. These mappings can cause issues. ctags-universal 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>=-pattern|extension options.
(Some of the heuristics are applied whether --guess-language-eagerly is given or not.)
Determining file language
If ctags-universal 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-universal 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-universal looks for a parser having the same name.
If ctags-universal finds no such parser, ctags-universal looks for the name in alias lists. For
example, consider if the first line is "#!/bin/sh". Though ctags-universal has a "shell" parser,
it doesn't have a "sh" parser. However, "sh" is listed as an alias for "shell", therefore
ctags-universal selects the "shell" parser for the file.
An exception is "env". If "env" is specified, ctags-universal reads more lines to find real
interpreter specification.
To display the list of aliases, use --list-aliases option. To add/remove an item to/from the
list, use the --alias-<LANG>=[+|-]aliasPattern option.
zsh autoload tag testing
If the first line starts with "#compdef" or "#autoload", ctags-universal 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-universal 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-universal 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-universal 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-universal regards the line as "php".
Looking into the file contents is a more expensive operation than file name matching. So ctags-universal
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-universal --print-language config.h.in input.m input.unknown
config.h.in: C++
input.m: MatLab
input.unknown: NONE
NONE means that ctags-universal does not select any parser for the file.
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.
Fields
A tag can record various information, called fields. The essential fields are: name of language objects,
input, pattern, and line. input: is the name of source file where name: is defined or referenced.
pattern: can be used to search the name in input:. line is the line number where name: is defined or
referenced in input:.
ctags-universal offers extension fields. See also the descriptions of --list-fields option and --fields
option.
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. See also the descriptions of --list-kinds-full option and --kinds-<LANG> option.
Extras
Generally, ctags-universal 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.
The following example demonstrates the "qualified" extra tag.
package Bar;
import Baz;
class Foo {
// ...
}
For the above source file, ctags-universal tags "Bar" and "Foo" by default. If the "qualified" extra is
enabled from the command line (--extras=+q), then "Bar.Foo" is also tagged even though the string
"Bar.Foo" is not in the source code.
See also the descriptions of --list-extras option and --extras option in "OPTION ITEMS".
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 example, for the source file used for demonstrating in the "Extras" subsection, "Baz" is tagged as a
reference tag with kind "package" and with role "imported". Another example is for a C++ "header" kind
tag, generated by "#include" statements: the roles:system or roles:local fields will be added depending
on whether the include file name begins with "<" or not.
See also the descriptions of --list-roles option.
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.
COMMAND LINE INTERFACE
Despite the wealth of available options, defaults are set so that ctags-universal is most commonly
executed without any options (e.g. "ctags-universal *", or "ctags-universal -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.
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.
Letters and names
Some options take letters 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 single
letters becomes difficult to understand.
Universal-ctags accepts names in addition to such letters. The names and letters can be mixed in an
option parameter by surrounding each 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 letters and associated names.
List options
Universal-ctags introduces many --list-... options that provide the internal data of Universal-ctags.
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.
OPTION ITEMS
ctags-universal 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.
-a Equivalent to --append.
-B Use backward searching patterns (e.g. ?pattern?). [Ignored in etags mode]
-e Same as --output-format=etags. Enable etags mode, which will create a tag file for use with the
Emacs editor. Alternatively, if ctags-universal 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 tags are written to standard output instead.
ctags-universal 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-universal -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]
-G Equivalent to --guess-language-eagerly.
-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
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 a plus sign, then the extensions in the list will be appended to the
current list; otherwise, the list will replace the current list. See, also, the --file-scope
option. The default list is ".h.H.hh.hpp.hxx.h++.inc.def". To restore the default list, specify -h
default. Note that if an extension supplied to this option is not already mapped to a particular
language (see "SOURCE FILES", above), you will also need to use either the --langmap or
--language-force option.
-I identifier-list
Specifies a list of identifiers which are to be specially handled while parsing C and C++ source
files. This option is specifically provided to handle special cases arising through the use of
preprocessor macros. When the identifiers listed are simple identifiers, these identifiers will
be ignored during parsing of the source files. If an identifier is suffixed with a '+' character,
ctags-universal 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 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".
-L file
Read from file a list of file names for which tags should be generated. If file is specified as
"-", then file names are read from standard input. File names read using this option are processed
following file names appearing on the command line. Options are also accepted in this input. If
this option is specified more than once, only the last will apply. Note: file is read in
line-oriented mode, where a new line is the only delimiter and non-trailing white space is
considered significant, in order that file names containing spaces may be supplied (however,
trailing white space is stripped from lines); this can affect how options are parsed if included
in the input.
-n Equivalent to --excmd=number.
-N Equivalent to --excmd=pattern.
-o tagfile
Equivalent to -f tagfile.
-R Equivalent to --recurse.
-u Equivalent to --sort=no (i.e. "unsorted").
-V Equivalent to --verbose.
-w This option is silently ignored for backward-compatibility with the ctags of SVR4 Unix.
-x Print a tabular, human-readable cross reference (xref) file to standard output instead of
generating a tag file. The information contained in the output includes: the tag name; the kind of
tag; the line number, file name, and source line (with extra white space condensed) of the file
which defines the tag. No tag file is written and all options affecting tag file output will be
ignored. Example applications for this feature are generating a listing of all functions located
in a source file (e.g. "ctags-universal -x --c-kinds=f file"), or generating a list of all
externally visible global variables located in a source file (e.g. "ctags-universal -x --c-kinds=v
--file-scope=no file"). This option must appear before the first file name.
--alias-<LANG>=[+|-]aliasPattern
Adds ('+') or removes ('-') an alias pattern to a language specified with <LANG>. ctags-universal
refers to the alias pattern in "Determining file language" stage.
The parameter aliasPattern 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" as the parameter aliasPattern. 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.
--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. This option must
appear before the first file name.
--etags-include=file
Include a reference to file in the tag file. This option may be specified as many times as
desired. This supports Emacs' capability to use a tag file which "includes" other tag files.
[Available only in etags mode]
--exclude=[pattern]
Add pattern to a list of excluded files and directories. This option may be specified as many
times as desired. For each file name considered by ctags-universal, 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-universal; 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.
--excmd=type
Determines the type of EX command used to locate tags in the source file. [Ignored in etags mode]
The valid values for type (either the entire word or the first letter is accepted) are:
number Use only line numbers in the tag file for locating tags. This has four advantages:
1. Significantly reduces the size of the resulting tag file.
2. Eliminates failures to find tags because the line defining the tag has changed, causing
the pattern match to fail (note that some editors, such as vim, are able to recover in
many such instances).
3. Eliminates finding identical matching, but incorrect, source lines (see "BUGS").
4. Retains separate entries in the tag file for lines which are identical in content. In
pattern mode, duplicate entries are dropped because the search patterns they generate
are identical, making the duplicate entries useless.
However, this option has one significant drawback: changes to the source files can cause
the line numbers recorded in the tag file to no longer correspond to the lines in the
source file, causing jumps to some tags to miss the target definition by one or more lines.
Basically, this option is best used when the source code to which it is applied is not
subject to change. Selecting this option type causes the following options to be ignored:
-BF.
pattern
Use only search patterns for all tags, rather than the line numbers usually used for macro
definitions. This has the advantage of not referencing obsolete line numbers when lines
have been added or removed since the tag file was generated.
mixed In this mode, patterns are generally used with a few exceptions. For C, line numbers are
used for macro definition tags. This was the default format generated by the original ctags
and is, therefore, retained as the default for this option. For Fortran, line numbers are
used for common blocks because their corresponding source lines are generally identical,
making pattern searches useless for finding all matches.
--extra=[+|-]flags|*
Equivalent to --extras=[+|-]flags|*, which was introduced to make the option naming convention
align to the other options like --kinds-<LANG>= and --fields=.
This option is kept for backward-compatibility with Exuberant-ctags.
--extras=[+|-]flags|*
Specifies whether to include extra tag entries for certain kinds of information. See also "Extras"
subsection to know what are kinds.
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 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.
The meaning of major extras is as follows (one-letter flag/name):
F/fileScope
Equivalent to --file-scope.
f/inputFile
Include an entry for the base file name of every source file (e.g. "example.c"), which
addresses the first line of the file. If the end: field is enabled, the end line number of
the file can be attached to the tag.
p/pseudo
Include pseudo tags. Enabled by default unless the tag file is written to standard output.
q/qualified
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.
r/reference
Include reference tags. See "TAG ENTRIES" about reference tags.
Inquire the output of --list-extras option for the other minor extras.
A name associated with an extra can be used as alternative to a one-letter flag. Some minor extras
have no one-letters flag. In that case, names must be specified anyway. See "Letters and names"
for more details.
--extras-<LANG>=[+|-]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-<LANG>=[+|-]flags|*
Specifies which language-specific fields are to be included in the entries of the tag file.
Universal-ctags supports language-specific fields. (See "Language-specific fields and extras"
about the concept). This option is for controlling them.
Specify "all" as <LANG> to apply the parameter flags to all fields; all fields are enabled with
specifying '*' as the parameter flags. If specifying nothing as the parameter flags
("--fields-all="), all extras are disabled. These two combinations are useful for testing.
--fields=[+|-]flags|*
Specifies which available extension fields are to be included in the tag entries (see "TAG FILE
FORMAT", below, and, "Fields", above, for more information).
The parameter flags is a set of one-letter flags, each representing one type of extension field to
include. 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 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.
This --fields= option is for controlling fields common in all languages (or language-independent
fields). Universal-ctags also supports language-specific fields. (See "Language-specific fields
and extras" about the concept). Use --fields-<LANG>= option for controlling them.
The meaning of major fields is as follows (one-letter flag/name):
a/access
Access (or export) of class members
e/end End lines of various items
f/file File-restricted scoping. Enabled by default.
i/inherits
Inheritance information.
k Kind of tag as a single letter. Enabled by default. Exceptionally this has no name.
K Kind of tag as full name Exceptionally this has no name.
l/language
Language of source file containing tag
m/implementation
Implementation information
n/line Line number of tag definition
p/scopeKind
Kind of scope as full name
r/roles
Roles assigned to the tag. For a definition tag, this field takes "def" as a value.
s Scope of tag definition. Enabled by default. Exceptionally this has no name.
S/signature
Signature of routine (e.g. prototype or parameter list)
t/typeref
Type and name of a variable, typedef or return type of callable like function as "typeref:"
field. Enabled by default.
z/kind Include the "kind:" key in kind field
Z Include the "scope:" key in scope field. Exceptionally this has no name.
Check the output of the --list-fields option for the other minor fields.
A name associated with a field can be used as alternative to a one-letter flag. Some minor fields
have no one-letters flag. In that case, names must be specified anyway. See "Letters and names"
for more details.
--file-scope[=yes|no]
Indicates whether tags scoped only for a single file (i.e. tags which cannot be seen outside of
the file in which they are defined, such as "static" tags) should be included in the output. See,
also, the -h option. This option is enabled by default.
Universal-ctags provides an alternative way to control this option, with the "F/fileScope" extra,
and recommends users to use the extra. However, this extra can cause issues. See
ctags-incompatibilities(7).
--filter[=yes|no]
Makes ctags-universal 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. This option must appear before the first file name.
--filter-terminator=string
Specifies a string to print to standard output following the tags for each file name parsed when
the --filter option is enabled. This may permit an application reading the output of
ctags-universal 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. This option must appear before the first file name.
--format=level
Change the format of the output tag file. Currently the only valid values for level are 1 or 2.
Level 1 specifies the original tag file format and level 2 specifies a new extended format
containing extension fields (but in a manner which retains backward-compatibility with original
vi(1) implementations). The default level is 2. This option must appear before the first file
name. [Ignored in etags mode]
--guess-language-eagerly
Looks into the file contents for heuristically guessing the proper language parser. See
"Determining file language".
--help Prints to standard output a detailed usage description, and then exits.
--help-full
Prints to standard output a detailed usage description about experimental features, and then
exits. Visit http://docs.ctags.io/en/latest for information about the latest exciting experimental
features.
--if0[=yes|no]
Indicates a preference as to whether code within an "#if 0" branch of a preprocessor conditional
should be examined for non-macro tags (macro tags are always included). Because the intent of this
construct is to disable code, the default value of this option is no. Note that this indicates a
preference only and does not guarantee skipping code within an "#if 0" branch, since the fall-back
algorithm used to generate tags when preprocessor conditionals are too complex follows all
branches of a conditional. This option is disabled by default.
--kinddef-<LANG>=letter,name,description
See ctags-optlib(7). Be not confused this with --kinds-<LANG>.
--kinds-<LANG>=[+|-]kinds|*
Specifies a list of language-specific kinds of tags (or kinds) to include in the output file for a
particular language, where <LANG> is case-insensitive and is one of the built-in language names
(see the --list-languages option for a complete list). The parameter kinds is a group of
one-letter flags designating kinds of tags (particular to the language) to either include or
exclude from the output. The specific sets of flags recognized for each language, their meanings
and defaults may be list using the --list-kinds-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-universal. Giving "all" makes sense only when '*' 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 "--c-kinds=+px-d"; to include only tags for
functions, use "--c-kinds=f".
A name associated with a kind can be used as alternative to a one-letter flag. See "Letters and
names" for more details.
--<LANG>-kinds=[+|-]kinds|*
Equivalent to --kinds-<LANG>=.... This option is kept for backward-compatibility with
Exuberant-ctags.
--langdef=name
See ctags-optlib(7).
--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-universal). 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.
--language-force=language
By default, ctags-universal automatically selects the language of a source file, ignoring those
files whose language cannot be determined (see "SOURCE FILES", above). This option forces the
specified language (case-insensitive; either built-in or user-defined) to be used for every
supplied file instead of automatically selecting the language based upon its extension. In
addition, the special value "auto" indicates that the language should be automatically selected
(which effectively disables this option).
--languages=[+|-]list
Specifies the languages for which tag generation is enabled, with list containing a
comma-separated list of language names (case-insensitive; either built-in or user-defined). If the
first language of list is not preceded by either a '+' or '-', the current list (the current
settings of enabled/disabled languages managed in ctags-universal 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 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 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.
--license
Prints a summary of the software license to standard output, and then exits.
--line-directives[=yes|no]
Specifies whether "#line" directives should be recognized. These are present in the output of
preprocessors and contain the line number, and possibly the file name, of the original source
file(s) from which the preprocessor output file was generated. When enabled, this option will
cause ctags-universal 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-universal.
--links[=yes|no]
Indicates whether symbolic links (if supported) should be followed. When disabled, symbolic links
are ignored. This option is on by default.
--list-aliases[=language|all]
Lists the aliases for either the specified language or all languages, and then exits. 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[=languages|all]
Lists the extras recognized for either the specified language or "all" languages. See "Extras"
subsection to know what are extras.
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 name as a
parameter for specifying an extra.
The meaning of columns are as follows:
LETTER One-letter flag. '-' means the extra does not have one-letter flag.
NAME The name of extra. The 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 "Fields"
subsection to know what are fields.
A field can be enabled or disabled with --fields= for common extras in all languages, or
--fields-<LANG>= for the specified language. These option takes one-letter flag or name as a
parameter for specifying a field.
The meaning of columns are as follows:
LETTER One-letter flag. '-' means the field does not have one-letter flag.
NAME The 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 the extra is common
in parsers.
JSTYPE Json type used in printing the value of field when "--output-format=json" is specified.
Following characters are used for representing types.
s string
i integer
b boolean (true or false)
The representation of this field and the output format used in "--output-format=json" are
still experimental.
FIXED Whether this field can be disabled or not. Some fields are printed always in tags output.
They have "yes" as the value for this column.
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.
Each kind of tag recorded in the tag file is represented by a one-letter flag, or name. 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 Name of the kind. This can be used as the alternative one-letter flag described above. If
enabling 'K' field with --fields=+K, ctags-universal uses name instead of letter in tags
output. To enable/disable a kind with --kinds-<LANG> option, name surrounded by braces
instead of 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 letter and/or the same name. 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 name 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-universal, 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.
This option does not work with --machinable nor --with-list-header.
--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.
--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.
--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. See the --langmap option, and
"SOURCE FILES", above.
To list the file extensions or file name patterns individually, use --list-map-extensions or
--list-map-patterns option. See the --langmap option, and "SOURCE FILES", above.
This option does not work with --machinable nor --with-list-header.
--list-regex-flags
See ctags-optlib(7).
--list-roles[=language|all[.kinds]]
List the roles for either the specified language or "all" languages. If the parameter kinds is
given after the parameter language or "all" with concatenating with '.', list only roles defined
in the kinds. Both one-letter flags and names surrounded by braces are acceptable as the parameter
kinds.
The meaning of columns are as follows:
LANGUAGE
Name of language having the role.
KIND(L/N)
One-letter flag and name of kind having the role.
NAME Name of the role.
ENABLED
Whether the kind is enabled or not. It takes "yes" or "no". (Currently all roles are
enabled. No option for disabling a specified role is not implemented yet.)
DESCRIPTION
Human readable description for the role.
--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.
--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-universal, 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.
--maxdepth
Limits the depth of directory recursion enabled with the --recurse (-R) option.
--options=pathname
Read additional options from file or directory.
ctags-universal searches pathname in optlib path list first. If ctags-universal cannot find a file
or directory in the list, ctags-universal 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 either a file or the environment (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 optlib path list. By default, the optlib path list is empty.
--print-language
Just prints the language parsers for specified source files, and then exits.
--quiet[=yes|no]
Write fewer messages (default is no).
--recurse[=yes|no]
Recurse into directories encountered in the list of supplied files. If the list of supplied files
is empty and no file list is specified with the -L option, then the current directory (i.e. ".")
is assumed. Symbolic links are followed. If you don't like these behaviors, either explicitly
specify the files or pipe the output of find(1) into ctags-universal -L- instead. Note: This
option is not supported on all platforms at present. It is available if the output of the --help
option includes this option. See, also, the --exclude to limit recursion.
--regex-<LANG>=/regexp/replacement/[kind-spec/][flags]
See ctags-optlib(7).
--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-universal readtags
library, or Vim version 6.2 or higher (using "set ignorecase"). This option must appear before the
first file name. [Ignored in etags mode]
--tag-relative[=yes|no]
Indicates that the file paths recorded in the tag file should be relative to the directory
containing the tag file, rather than relative to the current directory, unless the files supplied
on the command line are specified with absolute paths. This option must appear before the first
file name. The default is yes when running in etags mode (see the -e option), no otherwise.
--totals[=yes|no]
Prints statistics about the source files read and the tag file written during the current
invocation of ctags-universal. This option is off by default. This option must appear before the
first file name.
--verbose[=yes|no]
Enable verbose mode. This prints out information on option processing and a brief message
describing what action is being taken for each file considered by ctags-universal. Normally,
ctags-universal does not read command line arguments until after options are read from the
configuration files (see "FILES", below) and the CTAGS environment variable. However, if this
option is the first argument on the command line, it will take effect before any options are read
from these sources. The default is no.
--version
Prints a version identifier for ctags-universal to standard output, and then exits. This is
guaranteed to always contain the string "Universal Ctags".
--with-list-header[=yes|no]
Print headers describing columns in --list- option output. See also "List options".
OPERATIONAL DETAILS
As ctags-universal 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
filename 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). Additionallly, if the --guess-language-eagerly option is given, heuristic testing is also
performed to determine if a language parser applies. (See "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.
This implementation of ctags-universal 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-universal tries to be smart about conditional preprocessor directives. If a
preprocessor conditional is encountered within a statement which defines a tag, ctags-universal 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-universal 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-universal 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-universal will also try to specially handle arguments lists enclosed in double sets of parentheses
in order to accept the following conditional construct:
extern void foo __ARGS((int one, char two));
Any name immediately preceding the "((" will be automatically ignored and the previous name will be used.
C++ operator definitions are specially handled. In order for consistency with all types of operators
(overloaded and conversion), the operator name in the tag file will always be preceded by the string
"operator " (i.e. even if the actual operator definition was written as "operator<<").
After creating or appending to the tag file, it is sorted by the tag name, removing identical tag lines.
TAG FILE FORMAT
When not running in etags mode, each entry in the tag file consists of a separate line, each looking like
this in the most general case:
tag_name<TAB>file_name<TAB>ex_cmd;"<TAB>extension_fields
The fields and separators of these lines are specified as follows:
1. tag name
2. single tab character
3. name of the file in which the object associated with the tag is located
4. single tab character
5. EX command used to locate the tag within the file; generally a search pattern (either /pattern/ or
?pattern?) or line number (see --excmd). Tag file format 2 (see --format) extends this EX command
under certain circumstances to include a set of extension fields (described below) embedded in an
EX comment immediately appended to the EX command, which leaves it backward-compatible with
original vi(1) implementations.
A few special tags are written into the tag file for internal purposes. These tags are composed in such
a way that they always sort to the top of the file. Therefore, the first two characters of these tags are
used a magic number to detect a tag file for purposes of determining whether a valid tag file is being
overwritten rather than a source file.
Note that the name of each source file will be recorded in the tag file exactly as it appears on the
command line. Therefore, if the path you specified on the command line was relative to the current
directory, then it will be recorded in that same manner in the tag file. See, however, the --tag-relative
option for how this behavior can be modified.
Extension fields are tab-separated key-value pairs appended to the end of the EX command as a comment, as
described above. These key value pairs appear in the general form "key:value". Their presence in the
lines of the tag file are controlled by the --fields option. The possible keys and the meaning of their
values are as follows:
access Indicates the visibility of this class member, where value is specific to the language.
file Indicates that the tag has file-limited visibility. This key has no corresponding value.
kind Indicates the type, or kind, of tag. Its value is either one of the corresponding one-letter flags
described under the various --kinds-<LANG> options above, or a full name. It is permitted (and is,
in fact, the default) for the key portion of this field to be omitted. The optional behaviors are
controlled with the --fields option.
implementation
When present, this indicates a limited implementation (abstract vs. concrete) of a routine or
class, where value is specific to the language ("virtual" or "pure virtual" for C++; "abstract"
for Java).
inherits
When present, value. is a comma-separated list of classes from which this class is derived (i.e.
inherits from).
signature
When present, value is a language-dependent representation of the signature of a routine. A
routine signature in its complete form specifies the return type of a routine and its formal
argument list. This extension field is presently supported only for C-based languages and does
not include the return type.
In addition, information on the scope of the tag definition may be available, with the key portion equal
to some language-dependent construct name and its value the name declared for that construct in the
program. This scope entry indicates the scope in which the tag was found. For example, a tag generated
for a C structure member would have a scope looking like "struct:myStruct".
HOW TO USE WITH VI
Vi will, by default, expect a tag file by the name "tags" in the current directory. Once the tag file is
built, the following commands exercise the tag indexing feature:
vi -t tag
Start vi and position the cursor at the file and line where "tag" is defined.
:ta tag
Find a tag.
Ctrl-] Find the tag under the cursor.
Ctrl-T Return to previous location before jump to tag (not widely implemented).
HOW TO USE WITH GNU EMACS
Emacs will, by default, expect a tag file by the name "TAGS" in the current directory. Once the tag file
is built, the following commands exercise the tag indexing feature:
M-x visit-tags-table <RET> FILE <RET>
Select the tag file, "FILE", to use.
M-. [TAG] <RET>
Find the first definition of TAG. The default tag is the identifier under the cursor.
M-* Pop back to where you previously invoked "M-.".
C-u M-.
Find the next definition for the last tag.
For more commands, see the Tags topic in the Emacs info document.
HOW TO USE WITH NEDIT
NEdit version 5.1 and later can handle the new extended tag file format (see --format). To make NEdit use
the tag file, select "File->Load Tags File". To jump to the definition for a tag, highlight the word,
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-universal is neither a preprocessor nor a compiler, use of preprocessor macros can fool
ctags-universal into either missing tags or improperly generating inappropriate tags. Although
ctags-universal 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-universal. You can work around many such problems by using the -I option.
Note that since ctags-universal generates patterns for locating tags (see the --excmd option), it is
entirely possible that the wrong line may be found by your editor if there exists another source line
which is identical to the line containing the tag. The following example demonstrates this condition:
int variable;
/* ... */
void foo(variable)
int variable;
{
/* ... */
}
Depending upon which editor you use and where in the code you happen to be, it is possible that the
search pattern may locate the local parameter declaration in foo() before it finds the actual global
variable definition, since the lines (and therefore their search patterns are identical). This can be
avoided by use of the --excmd=n option.
BUGS
ctags-universal has more options than ls(1).
When parsing a C++ member function definition (e.g. "className::function"), ctags-universal cannot
determine whether the scope specifier is a class name or a namespace specifier and always lists it as a
class name in the scope portion of the extension fields. Also, if a C++ function is defined outside of
the class declaration (the usual case), the access specification (i.e. public, protected, or private) and
implementation information (e.g. virtual, pure virtual) contained in the function declaration are not
known when the tag is generated for the function definition. It will, however be available for prototypes
(e.g. "--c++-kinds=+p").
No qualified tags are generated for language objects inherited into a class.
ENVIRONMENT VARIABLES
CTAGS If this environment variable exists, it will be expected to contain a set of default options which
are read when ctags-universal 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-universal 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 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-universal is setuid, the value of TMPDIR
will be ignored.
FILES
$HOME/.ctags.d/*.ctags
$HOMEDRIVE$HOMEPATH/ctags.d/*.ctags (on MSWindows 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-universal starts, but before the CTAGS environment
variable is read or any command line options are read. This makes it possible to set up personal or
project-level defaults. It is possible to compile ctags-universal 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) 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.
tags The default tag file created by ctags-universal.
TAGS The default tag file created by etags.
SEE ALSO
See ctags-optlib(7) for defining (or extending) a parser in a configuration file.
The official Universal-ctags web site at:
https://ctags.io/
Also ex(1), vi(1), elvis, or, better yet, vim, the official editor of ctags. For more information on
vim, see the VIM Pages web site at:
http://www.vim.org/
AUTHOR
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 (Universal-ctags) derived from the repository, known as fishman-ctags,
started by Reza Jelveh.
Some parsers are taken from tagmanager of Geany (https://www.geany.org/) project.
The fishman-ctags was derived from Exuberant-ctags.
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.