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<h1 align=center>CTAGS</h1>

<a href="#NAME">NAME</a><br>
<a href="#SYNOPSIS">SYNOPSIS</a><br>
<a href="#DESCRIPTION">DESCRIPTION</a><br>
<a href="#SOURCE FILES">SOURCE FILES</a><br>
<a href="#OPTIONS">OPTIONS</a><br>
<a href="#OPERATIONAL DETAILS">OPERATIONAL DETAILS</a><br>
<a href="#TAG FILE FORMAT">TAG FILE FORMAT</a><br>
<a href="#HOW TO USE WITH VI">HOW TO USE WITH VI</a><br>
<a href="#HOW TO USE WITH GNU EMACS">HOW TO USE WITH GNU EMACS</a><br>
<a href="#HOW TO USE WITH NEDIT">HOW TO USE WITH NEDIT</a><br>
<a href="#CAVEATS">CAVEATS</a><br>
<a href="#BUGS">BUGS</a><br>
<a href="#ENVIRONMENT VARIABLES">ENVIRONMENT VARIABLES</a><br>
<a href="#FILES">FILES</a><br>
<a href="#SEE ALSO">SEE ALSO</a><br>
<a href="#AUTHOR">AUTHOR</a><br>
<a href="#MOTIVATION">MOTIVATION</a><br>
<a href="#CREDITS">CREDITS</a><br>

<hr>


<a name="NAME"></a>
<h2>NAME</h2>


<p style="margin-left:11%; margin-top: 1em">ctags &minus;
Generate tag files for source code</p>

<a name="SYNOPSIS"></a>
<h2>SYNOPSIS</h2>


<p style="margin-left:11%; margin-top: 1em"><b>ctags</b>
[<b>options</b>] [<i>file(s)</i>] <b><br>
etags</b> [<b>options</b>] [<i>file(s)</i>]</p>

<a name="DESCRIPTION"></a>
<h2>DESCRIPTION</h2>


<p style="margin-left:11%; margin-top: 1em">The
<b>ctags</b> and <b>etags</b> programs (hereinafter
collectively referred to as <b>ctags</b>, except where
distinguished) generate an index (or &quot;tag&quot;) file
for a variety of language objects found in <i>file(s)</i>.
This tag file allows these items to be quickly and easily
located by a text editor or other utility. A &quot;tag&quot;
signifies a language object for which an index entry is
available (or, alternatively, the index entry created for
that object).</p>

<p style="margin-left:11%; margin-top: 1em">Alternatively,
<b>ctags</b> can generate a cross reference file which
lists, in human readable form, information about the various
source objects found in a set of language files.</p>

<p style="margin-left:11%; margin-top: 1em">Tag index files
are supported by numerous editors, which allow the user to
locate the object associated with a name appearing in a
source file and jump to the file and line which defines the
name. Those known about at the time of this release are:</p>

<p style="margin-left:17%; margin-top: 1em"><b>Vi</b>(1)
and its derivatives (e.g. Elvis, Vim, Vile, Lemmy),
<b>CRiSP</b>, <b>Emacs</b>, <b>FTE</b> (Folding Text
Editor), <b>JED</b>, <b>jEdit</b>, <b>Mined</b>,
<b>NEdit</b> (Nirvana Edit), <b>TSE</b> (The SemWare
Editor), <b>UltraEdit</b>, <b>WorkSpace</b>, <b>X2</b>,
<b>Zeus</b></p>

<p style="margin-left:11%; margin-top: 1em"><b>Ctags</b> 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
<b>&minus;&minus;list&minus;languages</b> and
<b>&minus;&minus;list&minus;kinds</b> options.</p>

<a name="SOURCE FILES"></a>
<h2>SOURCE FILES</h2>


<p style="margin-left:11%; margin-top: 1em">Unless the
<b>&minus;&minus;language&minus;force</b> option is
specified, the language of each source file is automatically
selected based upon a mapping of file names to languages.
The mappings in effect for each language may be display
using the <b>&minus;&minus;list&minus;maps</b> option and
may be changed using the <b>&minus;&minus;langmap</b>
option. On platforms which support it, if the name of a file
is not mapped to a language and the file is executable, the
first line of the file is checked to see if the file is a
&quot;#!&quot; script for a recognized language.</p>

<p style="margin-left:11%; margin-top: 1em">By default, all
other files names are ignored. This permits running
<b>ctags</b> on all files in either a single directory (e.g.
&quot;ctags *&quot;), or on all files in an entire source
directory tree (e.g. &quot;ctags &minus;R&quot;), since only
those files whose names are mapped to languages will be
scanned.</p>

<p style="margin-left:11%; margin-top: 1em">[The reason
that .h extensions are mapped to C++ files rather than C
files is because it is common to use .h extensions in C++,
and no harm results in treating them as C++ files.]</p>

<a name="OPTIONS"></a>
<h2>OPTIONS</h2>


<p style="margin-left:11%; margin-top: 1em">Despite the
wealth of available options, defaults are set so that
<b>ctags</b> is most commonly executed without any options
(e.g. &quot;ctags *&quot;, or &quot;ctags &minus;R&quot;),
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.</p>

<p style="margin-left:11%; margin-top: 1em">Note that
spaces separating the single-letter options from their
parameters are optional.</p>

<p style="margin-left:11%; margin-top: 1em">Note also that
the boolean parameters to the long form options (those
beginning with &quot;&minus;&minus;&quot; and that take a
&quot;<i>[=yes</i>|<i>no]</i>&quot; parameter) may be
omitted, in which case &quot;<b>=</b><i>yes</i>&quot; is
implied. (e.g. <b>&minus;&minus;sort</b> is equivalent to
<b>&minus;&minus;sort</b>=<i>yes</i>). Note further that
&quot;=<i>1</i>&quot; and &quot;=<i>on</i>&quot; are
considered synonyms for &quot;=<i>yes</i>&quot;, and that
&quot;=<i>0</i>&quot; and &quot;=<i>off</i>&quot; are
considered synonyms for &quot;=<i>no</i>&quot;.</p>

<p style="margin-left:11%; margin-top: 1em">Some options
are either ignored or useful only when used while running in
etags mode (see <b>&minus;e</b> option). Such options will
be noted.</p>

<p style="margin-left:11%; margin-top: 1em">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.</p>

<p style="margin-left:11%; margin-top: 1em">Options taking
language names will accept those names in either upper or
lower case. See the
<b>&minus;&minus;list&minus;languages</b> option for a
complete list of the built-in language names.</p>

<table width="100%" border=0 rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">



<p style="margin-top: 1em" valign="top"><b>&minus;a</b></p> </td>
<td width="4%"></td>
<td width="82%">


<p style="margin-top: 1em" valign="top">Equivalent to
<b>&minus;&minus;append</b>.</p> </td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">


<p><b>&minus;B</b></p></td>
<td width="4%"></td>
<td width="82%">


<p>Use backward searching patterns (e.g. ?pattern?).
[Ignored in etags mode]</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">


<p><b>&minus;e</b></p></td>
<td width="4%"></td>
<td width="82%">


<p>Enable etags mode, which will create a tag file for use
with the Emacs editor. Alternatively, if <b>ctags</b> is
invoked by a name containing the string &quot;etags&quot;
(either by renaming, or creating a link to, the executable),
etags mode will be enabled. This option must appear before
the first file name.</p></td>
</table>

<p style="margin-left:11%;"><b>&minus;f</b>
<i>tagfile</i></p>

<p style="margin-left:18%;">Use the name specified by
<i>tagfile</i> for the tag file (default is
&quot;tags&quot;, or &quot;TAGS&quot; when running in etags
mode). If <i>tagfile</i> is specified as
&quot;&minus;&quot;, then the tag file is written to
standard output instead. <b>Ctags</b> will stubbornly refuse
to take orders if <i>tagfile</i> exists and its first line
contains something other than a valid tags line. This will
save your neck if you mistakenly type &quot;ctags &minus;f
*.c&quot;, 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
&rsquo;&minus;&rsquo; (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
&quot;&minus;ugly&quot;, specify it as
&quot;./&minus;ugly&quot;. This option must appear before
the first file name. If this option is specified more than
once, only the last will apply.</p>

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<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">



<p style="margin-top: 1em" valign="top"><b>&minus;F</b></p> </td>
<td width="4%"></td>
<td width="82%">


<p style="margin-top: 1em" valign="top">Use forward
searching patterns (e.g. /pattern/) (default). [Ignored in
etags mode]</p></td>
</table>

<p style="margin-left:11%;"><b>&minus;h</b> <i>list</i></p>

<p style="margin-left:18%;">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. &quot;.&quot;, &quot;..x&quot;,
&quot;.x.&quot;). This option only affects how the scoping
of a particular kinds of tags is interpreted (i.e. whether
or not they are considered as globally visible or visible
only within the file in which they are defined); it does not
map the extension to any particular language. Any tag which
is located in a non-include file and cannot be seen (e.g.
linked to) from another file is considered to have
file-limited (e.g. static) scope. No kind of tag appearing
in an include file will be considered to have file-limited
scope. If the first character in the list is a plus sign,
then the extensions in the list will be appended to the
current list; otherwise, the list will replace the current
list. See, also, the <b>&minus;&minus;file&minus;scope</b>
option. The default list is
&quot;.h.H.hh.hpp.hxx.h++.inc.def&quot;. To restore the
default list, specify <b>&minus;h</b> <i>default</i>. Note
that if an extension supplied to this option is not already
mapped to a particular language (see <b>SOURCE FILES</b>,
above), you will also need to use either the
<b>&minus;&minus;langmap</b> or
<b>&minus;&minus;language&minus;force</b> option.</p>

<p style="margin-left:11%;"><b>&minus;I</b>
<i>identifier&minus;list</i></p>

<p style="margin-left:18%;">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
&rsquo;+&rsquo; character, <b>ctags</b> 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 &rsquo;=&rsquo;
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
<i>identifier&minus;list</i> is &rsquo;@&rsquo;,
&rsquo;.&rsquo; or a pathname separator (&rsquo;/&rsquo; or
&rsquo;\&rsquo;), or the first two characters specify a
drive letter (e.g. &quot;C:&quot;), the parameter
<i>identifier&minus;list</i> will be interpreted as a
filename from which to read a list of identifiers, one per
input line. Otherwise, <i>identifier&minus;list</i> is a
list of identifiers (or identifier pairs) to be specially
handled, each delimited by a either a comma or by white
space (in which case the list should be quoted to keep the
entire list as one command line argument). Multiple
<b>&minus;I</b> options may be supplied. To clear the list
of ignore identifiers, supply a single dash
(&quot;&minus;&quot;) for <i>identifier&minus;list</i>.</p>

<p style="margin-left:18%; margin-top: 1em">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 <b>CAVEATS</b>, below). Some examples will
illustrate this point.</p>

<p style="margin-left:23%; margin-top: 1em">int foo
ARGDECL4(void *, ptr, long int, nbytes)</p>

<p style="margin-left:18%; margin-top: 1em">In the above
example, the macro &quot;ARGDECL4&quot; would be mistakenly
interpreted to be the name of the function instead of the
correct name of &quot;foo&quot;. Specifying <b>&minus;I</b>
<i>ARGDECL4</i> results in the correct behavior.</p>

<p style="margin-left:23%; margin-top: 1em">/* creates an
RCS version string in module */ <br>
MODULE_VERSION(&quot;$Revision: 690 $&quot;)</p>

<p style="margin-left:18%; margin-top: 1em">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&amp;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 <b>&minus;I</b>
<i>MODULE_VERSION+</i> would avoid such a problem.</p>

<p style="margin-left:23%; margin-top: 1em">CLASS Example {
<br>
// your content here <br>
};</p>

<p style="margin-left:18%; margin-top: 1em">The example
above uses &quot;CLASS&quot; as a preprocessor macro which
expands to something different for each platform. For
instance CLASS may be defined as &quot;class
__declspec(dllexport)&quot; on Win32 platforms and simply
&quot;class&quot; on UNIX. Normally, the absence of the C++
keyword &quot;class&quot; would cause the source file to be
incorrectly parsed. Correct behavior can be restored by
specifying <b>&minus;I</b> <i>CLASS=class</i>.</p>

<p style="margin-left:11%;"><b>&minus;L</b> <i>file</i></p>

<p style="margin-left:18%;">Read from <i>file</i> a list of
file names for which tags should be generated. If
<i>file</i> is specified as &quot;&minus;&quot;, 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. <b>Note:</b> <i>file</i> 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.</p>

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<td width="11%"></td>
<td width="3%">



<p style="margin-top: 1em" valign="top"><b>&minus;n</b></p> </td>
<td width="4%"></td>
<td width="47%">


<p style="margin-top: 1em" valign="top">Equivalent to
<b>&minus;&minus;excmd</b>=<i>number</i>.</p> </td>
<td width="35%">
</td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">


<p><b>&minus;N</b></p></td>
<td width="4%"></td>
<td width="47%">


<p>Equivalent to
<b>&minus;&minus;excmd</b>=<i>pattern</i>.</p> </td>
<td width="35%">
</td>
</table>

<p style="margin-left:11%;"><b>&minus;o</b>
<i>tagfile</i></p>

<p style="margin-left:18%;">Equivalent to <b>&minus;f</b>
<i>tagfile</i>.</p>

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       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">



<p style="margin-top: 1em" valign="top"><b>&minus;R</b></p> </td>
<td width="4%"></td>
<td width="82%">


<p style="margin-top: 1em" valign="top">Equivalent to
<b>&minus;&minus;recurse</b>.</p> </td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">


<p><b>&minus;u</b></p></td>
<td width="4%"></td>
<td width="82%">


<p>Equivalent to <b>&minus;&minus;sort</b>=<i>no</i> (i.e.
&quot;unsorted&quot;).</p> </td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">


<p><b>&minus;V</b></p></td>
<td width="4%"></td>
<td width="82%">


<p>Equivalent to <b>&minus;&minus;verbose</b>.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">


<p><b>&minus;w</b></p></td>
<td width="4%"></td>
<td width="82%">


<p>This option is silently ignored for
backward-compatibility with the ctags of SVR4 Unix.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">


<p><b>&minus;x</b></p></td>
<td width="4%"></td>
<td width="82%">


<p>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. <b>ctags
&minus;x &minus;&minus;c&minus;kinds</b>=<i>f file</i>), or
generating a list of all externally visible global variables
located in a source file (e.g. <b>ctags &minus;x
&minus;&minus;c&minus;kinds</b>=<i>v</i>
<b>&minus;&minus;file&minus;scope</b>=<i>no file</i>). This
option must appear before the first file name.</p></td>
</table>


<p style="margin-left:11%;"><b>&minus;&minus;append</b>[=<i>yes</i>|<i>no</i>]</p>

<p style="margin-left:18%;">Indicates whether tags
generated from the specified files should be appended to
those already present in the tag file or should replace
them. This option is off by default. This option must appear
before the first file name.</p>


<p style="margin-left:11%;"><b>&minus;&minus;etags&minus;include</b>=<i>file</i></p>

<p style="margin-left:18%;">Include a reference to
<i>file</i> in the tag file. This option may be specified as
many times as desired. This supports Emacs&rsquo; capability
to use a tag file which &quot;includes&quot; other tag
files. [Available only in etags mode]</p>


<p style="margin-left:11%;"><b>&minus;&minus;exclude</b>=[<i>pattern</i>]</p>

<p style="margin-left:18%;">Add <i>pattern</i> to a list of
excluded files and directories. This option may be specified
as many times as desired. For each file name considered by
<b>ctags</b>, each <i>pattern</i> 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 <i>pattern</i> 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
<b>ctags</b>; also be aware that wildcards can match the
slash character, &rsquo;/&rsquo;). You can determine if
shell wildcards are available on your platform by examining
the output of the <b>&minus;&minus;version</b> option, which
will include &quot;+wildcards&quot; in the compiled feature
list; otherwise, <i>pattern</i> is matched against file
names using a simple textual comparison.</p>

<p style="margin-left:18%; margin-top: 1em">If
<i>pattern</i> begins with the character &rsquo;@&rsquo;,
then the rest of the string is interpreted as a file name
from which to read exclusion patterns, one per line. If
<i>pattern</i> is empty, the list of excluded patterns is
cleared. Note that at program startup, the default exclude
list contains &quot;EIFGEN&quot;, &quot;SCCS&quot;,
&quot;RCS&quot;, and &quot;CVS&quot;, which are names of
directories for which it is generally not desirable to
descend while processing the <b>&minus;&minus;recurse</b>
option.</p>


<p style="margin-left:11%;"><b>&minus;&minus;excmd</b>=<i>type</i></p>

<p style="margin-left:18%;">Determines the type of EX
command used to locate tags in the source file. [Ignored in
etags mode]</p>

<p style="margin-left:18%; margin-top: 1em">The valid
values for <i>type</i> (either the entire word or the first
letter is accepted) are:</p>

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<tr valign="top" align="left">
<td width="18%"></td>
<td width="10%">


<p style="margin-top: 1em" valign="top"><i>number</i></p></td>
<td width="4%"></td>
<td width="68%">


<p style="margin-top: 1em" valign="top">Use only line
numbers in the tag file for locating tags. This has four
advantages:</p> </td>
</table>

<table width="100%" border=0 rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="32%"></td>
<td width="3%">


<p valign="top">1.</p></td>
<td width="3%"></td>
<td width="62%">


<p valign="top">Significantly reduces the size of the
resulting tag file.</p></td>
<tr valign="top" align="left">
<td width="32%"></td>
<td width="3%">


<p valign="top">2.</p></td>
<td width="3%"></td>
<td width="62%">


<p valign="top">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 <b>vim</b>,
are able to recover in many such instances).</p></td>
<tr valign="top" align="left">
<td width="32%"></td>
<td width="3%">


<p valign="top">3.</p></td>
<td width="3%"></td>
<td width="62%">


<p valign="top">Eliminates finding identical matching, but
incorrect, source lines (see <b>BUGS</b>, below).</p></td>
<tr valign="top" align="left">
<td width="32%"></td>
<td width="3%">


<p valign="top">4.</p></td>
<td width="3%"></td>
<td width="62%">


<p valign="top">Retains separate entries in the tag file
for lines which are identical in content. In <i>pattern</i>
mode, duplicate entries are dropped because the search
patterns they generate are identical, making the duplicate
entries useless.</p></td>
</table>

<p style="margin-left:32%; margin-top: 1em">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>&minus;BF</b>.</p>

<table width="100%" border=0 rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="18%"></td>
<td width="11%">


<p style="margin-top: 1em" valign="top"><i>pattern</i></p></td>
<td width="3%"></td>
<td width="68%">


<p style="margin-top: 1em" valign="top">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.</p></td>
<tr valign="top" align="left">
<td width="18%"></td>
<td width="11%">


<p><i>mixed</i></p></td>
<td width="3%"></td>
<td width="68%">


<p>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 <b>ctags</b> 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.</p></td>
</table>


<p style="margin-left:11%;"><b>&minus;&minus;extra</b>=<i>[+|&minus;]flags</i></p>

<p style="margin-left:18%;">Specifies whether to include
extra tag entries for certain kinds of information. The
parameter <i>flags</i> is a set of one-letter flags, each
representing one kind of extra tag entry to include in the
tag file. If <i>flags</i> is preceded by by either the
&rsquo;+&rsquo; or &rsquo;&minus;&rsquo; character, the
effect of each flag is added to, or removed from, those
currently enabled; otherwise the flags replace any current
settings. The meaning of each flag is as follows:</p>

<table width="100%" border=0 rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="23%"></td>
<td width="2%">


<p style="margin-top: 1em" valign="top"><i>f</i></p></td>
<td width="4%"></td>
<td width="71%">


<p style="margin-top: 1em" valign="top">Include an entry
for the base file name of every source file (e.g.
&quot;example.c&quot;), which addresses the first line of
the file.</p></td>
<tr valign="top" align="left">
<td width="23%"></td>
<td width="2%">


<p style="margin-top: 1em" valign="top"><i>q</i></p></td>
<td width="4%"></td>
<td width="71%">


<p style="margin-top: 1em" valign="top">Include an extra
class-qualified tag entry for each tag which is a member of
a class (for languages for which this information is
extracted; currently C++, Eiffel, and Java). The actual form
of the qualified tag depends upon the language from which
the tag was derived (using a form that is most natural for
how qualified calls are specified in the language). For C++,
it is in the form &quot;class::member&quot;; for Eiffel and
Java, it is in the form &quot;class.member&quot;. 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.</p></td>
</table>


<p style="margin-left:11%;"><b>&minus;&minus;fields</b>=<i>[+|&minus;]flags</i></p>

<p style="margin-left:18%;">Specifies the available
extension fields which are to be included in the entries of
the tag file (see <b>TAG FILE FORMAT</b>, below, for more
information). The parameter <i>flags</i> is a set of
one-letter flags, each representing one type of extension
field to include, with the following meanings (disabled by
default unless indicated):</p>

<table width="100%" border=0 rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="23%"></td>
<td width="2%">


<p style="margin-top: 1em" valign="top"><i>a</i></p></td>
<td width="4%"></td>
<td width="71%">


<p style="margin-top: 1em" valign="top">Access (or export)
of class members</p></td>
<tr valign="top" align="left">
<td width="23%"></td>
<td width="2%">


<p valign="top"><i>f</i></p></td>
<td width="4%"></td>
<td width="71%">


<p valign="top">File-restricted scoping [enabled]</p></td>
<tr valign="top" align="left">
<td width="23%"></td>
<td width="2%">


<p valign="top"><i>i</i></p></td>
<td width="4%"></td>
<td width="71%">


<p valign="top">Inheritance information</p></td>
<tr valign="top" align="left">
<td width="23%"></td>
<td width="2%">


<p valign="top"><i>k</i></p></td>
<td width="4%"></td>
<td width="71%">


<p valign="top">Kind of tag as a single letter
[enabled]</p> </td>
<tr valign="top" align="left">
<td width="23%"></td>
<td width="2%">


<p valign="top"><i>K</i></p></td>
<td width="4%"></td>
<td width="71%">


<p valign="top">Kind of tag as full name</p></td>
<tr valign="top" align="left">
<td width="23%"></td>
<td width="2%">


<p valign="top"><i>l</i></p></td>
<td width="4%"></td>
<td width="71%">


<p valign="top">Language of source file containing tag</p></td>
<tr valign="top" align="left">
<td width="23%"></td>
<td width="2%">


<p valign="top"><i>m</i></p></td>
<td width="4%"></td>
<td width="71%">


<p valign="top">Implementation information</p></td>
<tr valign="top" align="left">
<td width="23%"></td>
<td width="2%">


<p valign="top"><i>n</i></p></td>
<td width="4%"></td>
<td width="71%">


<p valign="top">Line number of tag definition</p></td>
<tr valign="top" align="left">
<td width="23%"></td>
<td width="2%">


<p valign="top"><i>s</i></p></td>
<td width="4%"></td>
<td width="71%">


<p valign="top">Scope of tag definition [enabled]</p></td>
<tr valign="top" align="left">
<td width="23%"></td>
<td width="2%">


<p valign="top"><i>S</i></p></td>
<td width="4%"></td>
<td width="71%">


<p valign="top">Signature of routine (e.g. prototype or
parameter list)</p></td>
<tr valign="top" align="left">
<td width="23%"></td>
<td width="2%">


<p valign="top"><i>z</i></p></td>
<td width="4%"></td>
<td width="71%">


<p valign="top">Include the &quot;kind:&quot; key in kind
field</p> </td>
<tr valign="top" align="left">
<td width="23%"></td>
<td width="2%">


<p valign="top"><i>t</i></p></td>
<td width="4%"></td>
<td width="71%">


<p valign="top">Type and name of a variable or typedef as
&quot;typeref:&quot; field [enabled]</p></td>
</table>

<p style="margin-left:18%; margin-top: 1em">Each letter or
group of letters may be preceded by either &rsquo;+&rsquo;
to add it to the default set, or &rsquo;&minus;&rsquo; to
exclude it. In the absence of any preceding &rsquo;+&rsquo;
or &rsquo;&minus;&rsquo; sign, only those kinds explicitly
listed in <i>flags</i> will be included in the output (i.e.
overriding the default set). This option is ignored if the
option <b>&minus;&minus;format</b>=<i>1</i> has been
specified. The default value of this option is
<i>fkst</i>.</p>


<p style="margin-left:11%;"><b>&minus;&minus;file&minus;scope</b>[=<i>yes</i>|<i>no</i>]</p>

<p style="margin-left:18%;">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
&quot;static&quot; tags) should be included in the output.
See, also, the <b>&minus;h</b> option. This option is
enabled by default.</p>


<p style="margin-left:11%;"><b>&minus;&minus;filter</b>[=<i>yes</i>|<i>no</i>]</p>

<p style="margin-left:18%;">Causes <b>ctags</b> to behave
as a filter, reading source file names from standard input
and printing their tags to standard output on a file-by-file
basis. If <b>&minus;&minus;sorted</b> 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 <b>&minus;L</b>
option) and only after file names listed on the command line
or from any file supplied using the <b>&minus;L</b> option.
When this option is enabled, the options <b>&minus;f</b>,
<b>&minus;o</b>, and <b>&minus;&minus;totals</b> are
ignored. This option is quite esoteric and is disabled by
default. This option must appear before the first file
name.</p>


<p style="margin-left:11%;"><b>&minus;&minus;filter&minus;terminator</b>=<i>string</i></p>

<p style="margin-left:18%;">Specifies a string to print to
standard output following the tags for each file name parsed
when the <b>&minus;&minus;filter</b> 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
<b>&minus;&minus;recurse</b> is enabled, this string will be
printed only one once at the end of all tags found for by
descending the directory. This string will always be
separated from the last tag line for the file by its
terminating newline. This option is quite esoteric and is
empty by default. This option must appear before the first
file name.</p>


<p style="margin-left:11%;"><b>&minus;&minus;format</b>=<i>level</i></p>

<p style="margin-left:18%;">Change the format of the output
tag file. Currently the only valid values for <i>level</i>
are <i>1</i> or <i>2</i>. 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 <b>vi</b>(1)
implementations). The default level is 2. This option must
appear before the first file name. [Ignored in etags
mode]</p>

<p style="margin-left:11%;"><b>&minus;&minus;help</b></p>

<p style="margin-left:18%;">Prints to standard output a
detailed usage description, and then exits.</p>


<p style="margin-left:11%;"><b>&minus;&minus;if0</b>[=<i>yes</i>|<i>no</i>]</p>

<p style="margin-left:18%;">Indicates a preference as to
whether code within an &quot;#if 0&quot; 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 <i>no</i>. Note that this indicates a preference
only and does not guarantee skipping code within an
&quot;#if 0&quot; 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.</p>


<p style="margin-left:11%;"><b>&minus;&minus;&lt;LANG&gt;&minus;kinds</b>=<i>[+|&minus;]kinds</i></p>

<p style="margin-left:18%;">Specifies a list of
language-specific kinds of tags (or kinds) to include in the
output file for a particular language, where
<b>&lt;LANG&gt;</b> is case-insensitive and is one of the
built-in language names (see the
<b>&minus;&minus;list&minus;languages</b> option for a
complete list). The parameter <i>kinds</i> 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
<b>&minus;&minus;list&minus;kinds</b> option. Each letter or
group of letters may be preceded by either &rsquo;+&rsquo;
to add it to, or &rsquo;&minus;&rsquo; to remove it from,
the default set. In the absence of any preceding
&rsquo;+&rsquo; or &rsquo;&minus;&rsquo; sign, only those
kinds explicitly listed in <i>kinds</i> will be included in
the output (i.e. overriding the default for the specified
language).</p>

<p style="margin-left:18%; margin-top: 1em">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
<b>&minus;&minus;c&minus;kinds</b>=<i>+px&minus;d</i>; to
include only tags for functions, use
<b>&minus;&minus;c&minus;kinds</b>=<i>f</i>.</p>


<p style="margin-left:11%;"><b>&minus;&minus;langdef</b>=<i>name</i></p>

<p style="margin-left:18%;">Defines a new user-defined
language, <i>name</i>, to be parsed with regular
expressions. Once defined, <i>name</i> may be used in other
options taking language names. The typical use of this
option is to first define the language, then map file names
to it using <i>&minus;&minus;langmap</i>, then specify
regular expressions using
<i>&minus;&minus;regex&minus;&lt;LANG&gt;</i> to define how
its tags are found.</p>


<p style="margin-left:11%;"><b>&minus;&minus;langmap</b>=<i>map[,map[...]]</i></p>

<p style="margin-left:18%;">Controls how file names are
mapped to languages (see the
<b>&minus;&minus;list&minus;maps</b> option). Each
comma-separated <i>map</i> 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. &quot;.c&quot;). A file name pattern is
specified by enclosing the pattern in parentheses (e.g.
&quot;([Mm]akefile)&quot;). 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 <b>ctags</b>). You can determine if
shell wildcards are available on your platform by examining
the output of the <b>&minus;&minus;version</b> option, which
will include &quot;+wildcards&quot; in the compiled feature
list; otherwise, the file name patterns are matched against
file names using a simple textual comparison. When mapping a
file extension, it will first be unmapped from any other
languages.</p>

<p style="margin-left:18%; margin-top: 1em">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
&quot;<b>&minus;&minus;langmap</b>=<i>c:.c.x</i>&quot;; to
also add files with extensions of .j as Java language files,
specify
&quot;<b>&minus;&minus;langmap</b>=<i>c:.c.x,java:+.j</i>&quot;.
To map makefiles (e.g. files named either
&quot;Makefile&quot;, &quot;makefile&quot;, or having the
extension &quot;.mak&quot;) to a language called
&quot;make&quot;, specify
&quot;<b>&minus;&minus;langmap</b>=<i>make:([Mm]akefile).mak</i>&quot;.
To map files having no extension, specify a period not
followed by a non-period character (e.g. &quot;.&quot;,
&quot;..x&quot;, &quot;.x.&quot;). To clear the mapping for
a particular language (thus inhibiting automatic generation
of tags for that language), specify an empty extension list
(e.g.
&quot;<b>&minus;&minus;langmap</b>=<i>fortran:</i>&quot;).
To restore the default language mappings for all a
particular language, supply the keyword &quot;default&quot;
for the mapping. To specify restore the default language
mappings for all languages, specify
&quot;<b>&minus;&minus;langmap</b>=<i>default</i>&quot;.
Note that file extensions are tested before file name
patterns when inferring the language of a file.</p>


<p style="margin-left:11%;"><b>&minus;&minus;language&minus;force</b>=<i>language</i></p>

<p style="margin-left:18%;">By default, <b>ctags</b>
automatically selects the language of a source file,
ignoring those files whose language cannot be determined
(see <b>SOURCE FILES</b>, above). This option forces the
specified <i>language</i> (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 <i>auto</i>
indicates that the language should be automatically selected
(which effectively disables this option).</p>


<p style="margin-left:11%;"><b>&minus;&minus;languages</b>=<i>[+|&minus;]list</i></p>

<p style="margin-left:18%;">Specifies the languages for
which tag generation is enabled, with <i>list</i> containing
a comma-separated list of language names (case-insensitive;
either built-in or user-defined). If the first language of
<i>list</i> is not preceded by either a &rsquo;+&rsquo; or
&rsquo;&minus;&rsquo;, the current list will be cleared
before adding or removing the languages in <i>list</i>.
Until a &rsquo;&minus;&rsquo; is encountered, each language
in the list will be added to the current list. As either the
&rsquo;+&rsquo; or &rsquo;&minus;&rsquo; 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
<b>&minus;&minus;langmap</b> option). Note that all
languages, including user-defined languages are enabled
unless explicitly disabled using this option. Language names
included in <i>list</i> may be any built-in language or one
previously defined with <b>&minus;&minus;langdef</b>. The
default is &quot;all&quot;, which is also accepted as a
valid argument. See the
<b>&minus;&minus;list&minus;languages</b> option for a
complete list of the built-in language names.</p>


<p style="margin-left:11%;"><b>&minus;&minus;license</b></p>

<p style="margin-left:18%;">Prints a summary of the
software license to standard output, and then exits.</p>


<p style="margin-left:11%;"><b>&minus;&minus;line&minus;directives</b>[=<i>yes</i>|<i>no</i>]</p>

<p style="margin-left:18%;">Specifies whether
&quot;#line&quot; 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 <b>ctags</b>
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. <b>Note:</b> This option is
generally only useful when used together with the
<b>&minus;&minus;excmd</b>=<i>number</i> (<b>&minus;n</b>)
option. Also, you may have to use either the
<b>&minus;&minus;langmap</b> or
<b>&minus;&minus;language&minus;force</b> option if the
extension of the preprocessor output file is not known to
<b>ctags</b>.</p>


<p style="margin-left:11%;"><b>&minus;&minus;links</b>[=<i>yes</i>|<i>no</i>]</p>

<p style="margin-left:18%;">Indicates whether symbolic
links (if supported) should be followed. When disabled,
symbolic links are ignored. This option is on by
default.</p>


<p style="margin-left:11%;"><b>&minus;&minus;list&minus;kinds</b>[=<i>language</i>|<i>all</i>]</p>

<p style="margin-left:18%;">Lists the tag kinds recognized
for either the specified language or all languages, and then
exits. Each kind of tag recorded in the tag file is
represented by a one-letter flag, which is also used to
filter the tags placed into the output through use of the
<b>&minus;&minus;&lt;LANG&gt;&minus;kinds</b> option. Note
that some languages and/or tag kinds may be implemented
using regular expressions and may not be available if regex
support is not compiled into <b>ctags</b> (see the
<b>&minus;&minus;regex&minus;&lt;LANG&gt;</b> option). Each
kind listed is enabled unless followed by
&quot;[off]&quot;.</p>


<p style="margin-left:11%;"><b>&minus;&minus;list&minus;maps</b>[=<i>language</i>|<i>all</i>]</p>

<p style="margin-left:18%;">Lists the file extensions and
file name patterns which associate a file name with a
language for either the specified language or all languages,
and then exits. See the <b>&minus;&minus;langmap</b> option,
and <b>SOURCE FILES</b>, above.</p>


<p style="margin-left:11%;"><b>&minus;&minus;list&minus;languages</b></p>

<p style="margin-left:18%;">Lists the names of the
languages understood by <b>ctags</b>, and then exits. These
language names are case insensitive and may be used in the
<b>&minus;&minus;language&minus;force</b>,
<b>&minus;&minus;languages</b>,
<b>&minus;&minus;&lt;LANG&gt;&minus;kinds</b>, and
<b>&minus;&minus;regex&minus;&lt;LANG&gt;</b> options.</p>


<p style="margin-left:11%;"><b>&minus;&minus;options</b>=<i>file</i></p>

<p style="margin-left:18%;">Read additional options from
<i>file</i>. The file should contain one option per line. As
a special case, if <b>&minus;&minus;options</b>=<i>NONE</i>
is specified as the first option on the command line, it
will disable the automatic reading of any configuration
options from either a file or the environment (see
<b>FILES</b>).</p>


<p style="margin-left:11%;"><b>&minus;&minus;recurse</b>[=<i>yes</i>|<i>no</i>]</p>

<p style="margin-left:18%;">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 <b>&minus;L</b> option, then the current directory (i.e.
&quot;.&quot;) is assumed. Symbolic links are followed. If
you don&rsquo;t like these behaviors, either explicitly
specify the files or pipe the output of <b>find</b>(1) into
<b>ctags &minus;L&minus;</b> instead. <b>Note:</b> This
option is not supported on all platforms at present. It is
available if the output of the <b>&minus;&minus;help</b>
option includes this option. See, also, the
<b>&minus;&minus;exclude</b> to limit recursion.</p>


<p style="margin-left:11%;"><b>&minus;&minus;regex&minus;&lt;LANG&gt;</b>=<i>/regexp/replacement/[kind&minus;spec/][flags]</i></p>

<p style="margin-left:18%;">The <i>/regexp/replacement/</i>
pair define a regular expression replacement pattern,
similar in style to <b>sed</b> substitution commands, with
which to generate tags from source files mapped to the named
language, <b>&lt;LANG&gt;</b>, (case-insensitive; either a
built-in or user-defined language). The regular expression,
<i>regexp</i>, defines an extended regular expression
(roughly that used by <b>egrep</b>(1)), which is used to
locate a single source line containing a tag and may specify
tab characters using \t. When a matching line is found, a
tag will be generated for the name defined by
<i>replacement</i>, which generally will contain the special
back-references \1 through \9 to refer to matching
sub-expression groups within <i>regexp</i>. The
&rsquo;/&rsquo; separator characters shown in the parameter
to the option can actually be replaced by any character.
Note that whichever separator character is used will have to
be escaped with a backslash (&rsquo;\&rsquo;) character
wherever it is used in the parameter as something other than
a separator. The regular expression defined by this option
is added to the current list of regular expressions for the
specified language unless the parameter is omitted, in which
case the current list is cleared.</p>

<p style="margin-left:18%; margin-top: 1em">Unless modified
by <i>flags</i>, <i>regexp</i> is interpreted as a Posix
extended regular expression. The <i>replacement</i> should
expand for all matching lines to a non-empty string of
characters, or a warning message will be reported. An
optional kind specifier for tags matching <i>regexp</i> may
follow <i>replacement</i>, which will determine what kind of
tag is reported in the &quot;kind&quot; extension field (see
<b>TAG FILE FORMAT</b>, below). The full form of
<i>kind&minus;spec</i> is in the form of a single letter, a
comma, a name (without spaces), a comma, a description,
followed by a separator, which specify the short and long
forms of the kind value and its textual description
(displayed using <b>&minus;&minus;list&minus;kinds</b>).
Either the kind name and/or the description may be omitted.
If <i>kind&minus;spec</i> is omitted, it defaults to
&quot;<i>r,regex</i>&quot;. Finally, <i>flags</i> are one or
more single-letter characters having the following effect
upon the interpretation of <i>regexp</i>:</p>

<table width="100%" border=0 rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="23%"></td>
<td width="2%">


<p style="margin-top: 1em" valign="top"><i>b</i></p></td>
<td width="4%"></td>
<td width="71%">


<p style="margin-top: 1em" valign="top">The pattern is
interpreted as a Posix basic regular expression.</p></td>
<tr valign="top" align="left">
<td width="23%"></td>
<td width="2%">


<p style="margin-top: 1em" valign="top"><i>e</i></p></td>
<td width="4%"></td>
<td width="71%">


<p style="margin-top: 1em" valign="top">The pattern is
interpreted as a Posix extended regular expression
(default).</p> </td>
<tr valign="top" align="left">
<td width="23%"></td>
<td width="2%">


<p style="margin-top: 1em" valign="top"><i>i</i></p></td>
<td width="4%"></td>
<td width="71%">


<p style="margin-top: 1em" valign="top">The regular
expression is to be applied in a case-insensitive
manner.</p> </td>
</table>

<p style="margin-left:18%; margin-top: 1em">Note that this
option is available only if <b>ctags</b> was compiled with
support for regular expressions, which depends upon your
platform. You can determine if support for regular
expressions is compiled in by examining the output of the
<b>&minus;&minus;version</b> option, which will include
&quot;+regex&quot; in the compiled feature list.</p>

<p style="margin-left:18%; margin-top: 1em">For more
information on the regular expressions used by <b>ctags</b>,
see either the <b>regex(5,7)</b> man page, or the GNU info
documentation for regex (e.g. &quot;info regex&quot;).</p>


<p style="margin-left:11%;"><b>&minus;&minus;sort</b>[=<i>yes</i>|<i>no</i>|<i>foldcase</i>]</p>

<p style="margin-left:18%;">Indicates whether the tag file
should be sorted on the tag name (default is <i>yes</i>).
Note that the original <b>vi</b>(1) required sorted tags.
The <i>foldcase</i> 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
&quot;set ignorecase&quot;). This option must appear before
the first file name. [Ignored in etags mode]</p>


<p style="margin-left:11%;"><b>&minus;&minus;tag&minus;relative</b>[=<i>yes</i>|<i>no</i>]</p>

<p style="margin-left:18%;">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 <i>yes</i> when
running in etags mode (see the <b>&minus;e</b> option),
<i>no</i> otherwise.</p>


<p style="margin-left:11%;"><b>&minus;&minus;totals</b>[=<i>yes</i>|<i>no</i>]</p>

<p style="margin-left:18%;">Prints statistics about the
source files read and the tag file written during the
current invocation of <b>ctags</b>. This option is off by
default. This option must appear before the first file
name.</p>


<p style="margin-left:11%;"><b>&minus;&minus;verbose</b>[=<i>yes</i>|<i>no</i>]</p>

<p style="margin-left:18%;">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 <b>ctags</b>. Normally, <b>ctags</b> does not
read command line arguments until after options are read
from the configuration files (see <b>FILES</b>, below) and
the <b>CTAGS</b> 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 <i>no</i>.</p>


<p style="margin-left:11%;"><b>&minus;&minus;version</b></p>

<p style="margin-left:18%;">Prints a version identifier for
<b>ctags</b> to standard output, and then exits. This is
guaranteed to always contain the string &quot;Exuberant
Ctags&quot;.</p>

<a name="OPERATIONAL DETAILS"></a>
<h2>OPERATIONAL DETAILS</h2>


<p style="margin-left:11%; margin-top: 1em">As <b>ctags</b>
considers each file name in turn, it tries to determine the
language of the file by applying the following three tests
in order: if the file extension has been mapped to a
language, if the file name matches a shell pattern mapped to
a language, and finally if the file is executable and its
first line specifies an interpreter using the Unix-style
&quot;#!&quot; specification (if supported on the platform).
If a language was identified, the file is opened and then
the appropriate language parser is called to operate on the
currently open file. The parser parses through the file and
adds an entry to the tag file for each language object it is
written to handle. See <b>TAG FILE FORMAT</b>, below, for
details on these entries.</p>

<p style="margin-left:11%; margin-top: 1em">This
implementation of <b>ctags</b> 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.</p>

<p style="margin-left:11%; margin-top: 1em">In general,
<b>ctags</b> tries to be smart about conditional
preprocessor directives. If a preprocessor conditional is
encountered within a statement which defines a tag,
<b>ctags</b> follows only the first branch of that
conditional (except in the special case of &quot;#if
0&quot;, 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:</p>

<p style="margin-left:22%; margin-top: 1em">#ifdef
TWO_ALTERNATIVES <br>
struct { <br>
#else <br>
union { <br>
#endif</p>

<p style="margin-left:28%;">short a; <br>
long b;</p>

<p style="margin-left:22%;">}</p>

<p style="margin-left:11%; margin-top: 1em">Both branches
cannot be followed, or braces become unbalanced and
<b>ctags</b> would be unable to make sense of the
syntax.</p>

<p style="margin-left:11%; margin-top: 1em">If the
application of this heuristic fails to properly parse a
file, generally due to complicated and inconsistent pairing
within the conditionals, <b>ctags</b> 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 (&quot;}&quot;) in
column 1 as indicating the end of a block once any brace
imbalance results from following a #if conditional
branch.</p>

<p style="margin-left:11%; margin-top: 1em"><b>Ctags</b>
will also try to specially handle arguments lists enclosed
in double sets of parentheses in order to accept the
following conditional construct:</p>

<p style="margin-left:22%; margin-top: 1em">extern void foo
__ARGS((int one, char two));</p>

<p style="margin-left:11%; margin-top: 1em">Any name
immediately preceding the &quot;((&quot; will be
automatically ignored and the previous name will be
used.</p>

<p style="margin-left:11%; margin-top: 1em">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 &quot;operator &quot; (i.e. even if the actual
operator definition was written as
&quot;operator&lt;&lt;&quot;).</p>

<p style="margin-left:11%; margin-top: 1em">After creating
or appending to the tag file, it is sorted by the tag name,
removing identical tag lines.</p>

<a name="TAG FILE FORMAT"></a>
<h2>TAG FILE FORMAT</h2>


<p style="margin-left:11%; margin-top: 1em">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:</p>


<p style="margin-left:12%; margin-top: 1em">tag_name&lt;TAB&gt;file_name&lt;TAB&gt;ex_cmd;&quot;&lt;TAB&gt;extension_fields</p>

<p style="margin-left:11%; margin-top: 1em">The fields and
separators of these lines are specified as follows:</p>

<table width="100%" border=0 rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="17%"></td>
<td width="3%">


<p style="margin-top: 1em" valign="top">1.</p></td>
<td width="3%"></td>
<td width="77%">


<p style="margin-top: 1em" valign="top">tag name</p></td>
<tr valign="top" align="left">
<td width="17%"></td>
<td width="3%">


<p valign="top">2.</p></td>
<td width="3%"></td>
<td width="77%">


<p valign="top">single tab character</p></td>
<tr valign="top" align="left">
<td width="17%"></td>
<td width="3%">


<p valign="top">3.</p></td>
<td width="3%"></td>
<td width="77%">


<p valign="top">name of the file in which the object
associated with the tag is located</p></td>
<tr valign="top" align="left">
<td width="17%"></td>
<td width="3%">


<p valign="top">4.</p></td>
<td width="3%"></td>
<td width="77%">


<p valign="top">single tab character</p></td>
<tr valign="top" align="left">
<td width="17%"></td>
<td width="3%">


<p valign="top">5.</p></td>
<td width="3%"></td>
<td width="77%">


<p valign="top">EX command used to locate the tag within
the file; generally a search pattern (either /pattern/ or
?pattern?) or line number (see <b>&minus;&minus;excmd</b>).
Tag file format 2 (see <b>&minus;&minus;format</b>) 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 <b>vi</b>(1)
implementations.</p> </td>
</table>

<p style="margin-left:11%; margin-top: 1em">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.</p>

<p style="margin-left:11%; margin-top: 1em">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
<b>&minus;&minus;tag&minus;relative</b> option for how this
behavior can be modified.</p>

<p style="margin-left:11%; margin-top: 1em">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
&quot;<i>key</i>:<i>value</i>&quot;. Their presence in the
lines of the tag file are controlled by the
<b>&minus;&minus;fields</b> option. The possible keys and
the meaning of their values are as follows:</p>

<table width="100%" border=0 rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">


<p style="margin-top: 1em" valign="top"><i>access</i></p></td>
<td width="9%"></td>
<td width="71%">


<p style="margin-top: 1em" valign="top">Indicates the
visibility of this class member, where <i>value</i> is
specific to the language.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">


<p><i>file</i></p></td>
<td width="9%"></td>
<td width="71%">


<p>Indicates that the tag has file-limited visibility. This
key has no corresponding value.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">


<p><i>kind</i></p></td>
<td width="9%"></td>
<td width="71%">


<p>Indicates the type, or kind, of tag. Its value is either
one of the corresponding one-letter flags described under
the various <b>&minus;&minus;&lt;LANG&gt;&minus;kinds</b>
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
<b>&minus;&minus;fields</b> option.</p></td>
</table>

<p style="margin-left:11%;"><i>implementation</i></p>

<p style="margin-left:29%;">When present, this indicates a
limited implementation (abstract vs. concrete) of a routine
or class, where <i>value</i> is specific to the language
(&quot;virtual&quot; or &quot;pure virtual&quot; for C++;
&quot;abstract&quot; for Java).</p>

<table width="100%" border=0 rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="14%">



<p style="margin-top: 1em" valign="top"><i>inherits</i></p> </td>
<td width="4%"></td>
<td width="71%">


<p style="margin-top: 1em" valign="top">When present,
<i>value</i>. is a comma-separated list of classes from
which this class is derived (i.e. inherits from).</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="14%">


<p><i>signature</i></p></td>
<td width="4%"></td>
<td width="71%">


<p>When present, <i>value</i> 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.</p></td>
</table>

<p style="margin-left:11%; margin-top: 1em">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 &quot;struct:myStruct&quot;.</p>

<a name="HOW TO USE WITH VI"></a>
<h2>HOW TO USE WITH VI</h2>


<p style="margin-left:11%; margin-top: 1em">Vi will, by
default, expect a tag file by the name &quot;tags&quot; in
the current directory. Once the tag file is built, the
following commands exercise the tag indexing feature:</p>

<table width="100%" border=0 rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="14%">


<p style="margin-top: 1em" valign="top"><b>vi &minus;t
tag</b></p> </td>
<td width="4%"></td>
<td width="71%">


<p style="margin-top: 1em" valign="top">Start vi and
position the cursor at the file and line where
&quot;tag&quot; is defined.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="14%">


<p style="margin-top: 1em" valign="top"><b>:ta tag</b></p></td>
<td width="4%"></td>
<td width="71%">


<p style="margin-top: 1em" valign="top">Find a tag.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="14%">


<p style="margin-top: 1em" valign="top"><b>Ctrl-]</b></p></td>
<td width="4%"></td>
<td width="71%">


<p style="margin-top: 1em" valign="top">Find the tag under
the cursor.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="14%">


<p style="margin-top: 1em" valign="top"><b>Ctrl-T</b></p></td>
<td width="4%"></td>
<td width="71%">


<p style="margin-top: 1em" valign="top">Return to previous
location before jump to tag (not widely implemented).</p></td>
</table>

<a name="HOW TO USE WITH GNU EMACS"></a>
<h2>HOW TO USE WITH GNU EMACS</h2>


<p style="margin-left:11%; margin-top: 1em">Emacs will, by
default, expect a tag file by the name &quot;TAGS&quot; in
the current directory. Once the tag file is built, the
following commands exercise the tag indexing feature:
<b><br>
M-x visit&minus;tags&minus;table &lt;RET&gt; FILE
&lt;RET&gt;</b></p>

<p style="margin-left:26%;">Select the tag file,
&quot;FILE&quot;, to use.</p>

<p style="margin-left:11%;"><b>M-. [TAG]
&lt;RET&gt;</b></p>

<p style="margin-left:26%;">Find the first definition of
TAG. The default tag is the identifier under the cursor.</p>

<table width="100%" border=0 rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="11%">


<p style="margin-top: 1em" valign="top"><b>M-*</b></p></td>
<td width="4%"></td>
<td width="72%">


<p style="margin-top: 1em" valign="top">Pop back to where
you previously invoked &quot;M-.&quot;.</p></td>
<td width="2%">
</td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="11%">


<p style="margin-top: 1em" valign="top"><b>C-u M-.</b></p></td>
<td width="4%"></td>
<td width="72%">


<p style="margin-top: 1em" valign="top">Find the next
definition for the last tag.</p></td>
<td width="2%">
</td>
</table>

<p style="margin-left:11%; margin-top: 1em">For more
commands, see the <i>Tags</i> topic in the Emacs info
document.</p>

<a name="HOW TO USE WITH NEDIT"></a>
<h2>HOW TO USE WITH NEDIT</h2>


<p style="margin-left:11%; margin-top: 1em">NEdit version
5.1 and later can handle the new extended tag file format
(see <b>&minus;&minus;format</b>). To make NEdit use the tag
file, select &quot;File&minus;&gt;Load Tags File&quot;. To
jump to the definition for a tag, highlight the word, the
press Ctrl-D. NEdit 5.1 can can read multiple tag files from
different directories. Setting the X resource nedit.tagFile
to the name of a tag file instructs NEdit to automatically
load that tag file at startup time.</p>

<a name="CAVEATS"></a>
<h2>CAVEATS</h2>


<p style="margin-left:11%; margin-top: 1em">Because
<b>ctags</b> is neither a preprocessor nor a compiler, use
of preprocessor macros can fool <b>ctags</b> into either
missing tags or improperly generating inappropriate tags.
Although <b>ctags</b> 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 <b>ctags</b>.
You can work around many such problems by using the
<b>&minus;I</b> option.</p>

<p style="margin-left:11%; margin-top: 1em">Note that since
<b>ctags</b> generates patterns for locating tags (see the
<b>&minus;&minus;excmd</b> 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:</p>

<p style="margin-left:22%; margin-top: 1em">int
variable;</p>

<p style="margin-left:22%; margin-top: 1em">/* ... */ <br>
void foo(variable) <br>
int variable; <br>
{</p>

<p style="margin-left:28%;">/* ... */</p>

<p style="margin-left:22%;">}</p>

<p style="margin-left:11%; margin-top: 1em">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 <b>&minus;&minus;excmd</b>=<i>n</i> option.</p>

<a name="BUGS"></a>
<h2>BUGS</h2>


<p style="margin-left:11%; margin-top: 1em"><b>Ctags</b>
has more options than <b>ls</b>(1).</p>

<p style="margin-left:11%; margin-top: 1em">When parsing a
C++ member function definition (e.g.
&quot;className::function&quot;), <b>ctags</b> 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 <b>&minus;&minus;c++&minus;kinds</b>=<i>+p</i>).</p>

<p style="margin-left:11%; margin-top: 1em">No qualified
tags are generated for language objects inherited into a
class.</p>

<a name="ENVIRONMENT VARIABLES"></a>
<h2>ENVIRONMENT VARIABLES</h2>


<table width="100%" border=0 rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">


<p style="margin-top: 1em" valign="top"><b>CTAGS</b></p></td>
<td width="3%"></td>
<td width="77%">


<p style="margin-top: 1em" valign="top">If this environment
variable exists, it will be expected to contain a set of
default options which are read when <b>ctags</b> starts,
after the configuration files listed in <b>FILES</b>, 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.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">


<p><b>ETAGS</b></p></td>
<td width="3%"></td>
<td width="77%">


<p>Similar to the <b>CTAGS</b> variable above, this
variable, if found, will be read when <b>etags</b> starts.
If this variable is not found, <b>etags</b> will try to use
<b>CTAGS</b> instead.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">


<p><b>TMPDIR</b></p></td>
<td width="3%"></td>
<td width="77%">


<p>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. <b>ctags</b> creates temporary files only
if either (1) an emacs-style tag file is being generated,
(2) the tag file is being sent to standard output, or (3)
the program was compiled to use an internal sort algorithm
to sort the tag files instead of the the sort utility of the
operating system. If the sort utility of the operating
system is being used, it will generally observe this
variable also. Note that if <b>ctags</b> is setuid, the
value of TMPDIR will be ignored.</p></td>
</table>

<a name="FILES"></a>
<h2>FILES</h2>


<p style="margin-left:11%; margin-top: 1em"><i>/ctags.cnf
(on MSDOS, MSWindows only) <br>
/etc/ctags.conf <br>
/usr/local/etc/ctags.conf <br>
$HOME/.ctags <br>
$HOME/ctags.cnf (on MSDOS, MSWindows only) <br>
.ctags <br>
ctags.cnf (on MSDOS, MSWindows only)</i></p>

<p style="margin-left:22%;">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
<b>ctags</b> starts, but before the <b>CTAGS</b> environment
variable is read or any command line options are read. This
makes it possible to set up site-wide, personal or
project-level defaults. It is possible to compile
<b>ctags</b> to read an additional configuration file before
any of those shown above, which will be indicated if the
output produced by the <b>&minus;&minus;version</b> option
lists the &quot;custom-conf&quot; feature. Options appearing
in the <b>CTAGS</b> environment variable or on the command
line will override options specified in these files. Only
options will be read from these files. Note that the option
files are read in line-oriented mode in which spaces are
significant (since shell quoting is not possible). Each line
of the file is read as one command line parameter (as if it
were quoted with single quotes). Therefore, use new lines to
indicate separate command-line arguments.</p>

<table width="100%" border=0 rules="none" frame="void"
       cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="6%">


<p style="margin-top: 1em" valign="top"><i>tags</i></p></td>
<td width="5%"></td>
<td width="58%">


<p style="margin-top: 1em" valign="top">The default tag
file created by <b>ctags</b>.</p></td>
<td width="20%">
</td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="6%">


<p style="margin-top: 1em" valign="top"><i>TAGS</i></p></td>
<td width="5%"></td>
<td width="58%">


<p style="margin-top: 1em" valign="top">The default tag
file created by <b>etags</b>.</p></td>
<td width="20%">
</td>
</table>

<a name="SEE ALSO"></a>
<h2>SEE ALSO</h2>


<p style="margin-left:11%; margin-top: 1em">The official
Exuberant Ctags web site at:</p>


<p style="margin-left:22%; margin-top: 1em">http://ctags.sourceforge.net</p>

<p style="margin-left:11%; margin-top: 1em">Also
<b>ex</b>(1), <b>vi</b>(1), <b>elvis</b>, or, better yet,
<b>vim</b>, the official editor of <b>ctags</b>. For more
information on <b>vim</b>, see the VIM Pages web site
at:</p>


<p style="margin-left:22%; margin-top: 1em">http://www.vim.org/</p>

<a name="AUTHOR"></a>
<h2>AUTHOR</h2>


<p style="margin-left:11%; margin-top: 1em">Darren Hiebert
&lt;dhiebert at users.sourceforge.net&gt; <br>
http://DarrenHiebert.com/</p>

<a name="MOTIVATION"></a>
<h2>MOTIVATION</h2>


<p style="margin-left:11%; margin-top: 1em">&quot;Think ye
at all times of rendering some service to every member of
the human race.&quot;</p>

<p style="margin-left:11%; margin-top: 1em">&quot;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.&quot;</p>

<p style="margin-left:22%; margin-top: 1em">&minus;&minus;
From the Baha&rsquo;i Writings</p>

<a name="CREDITS"></a>
<h2>CREDITS</h2>


<p style="margin-left:11%; margin-top: 1em">This version of
<b>ctags</b> was originally derived from and inspired by the
ctags program by Steve Kirkendall
&lt;kirkenda@cs.pdx.edu&gt; that comes with the Elvis vi
clone (though virtually none of the original code
remains).</p>

<p style="margin-left:11%; margin-top: 1em">Credit is also
due Bram Moolenaar &lt;Bram@vim.org&gt;, the author of
<b>vim</b>, 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.</p>

<p style="margin-left:11%; margin-top: 1em">The section
entitled &quot;HOW TO USE WITH GNU EMACS&quot; was
shamelessly stolen from the info page for GNU
<b>etags</b>.</p>
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