elvtags

CTAGS(1)                    General Commands Manual                   CTAGS(1)



NAME
       ctags - Generates "tags" and (optionally) "refs" files

SYNOPSIS
       ctags [-D word] [-FBNitvshlpxra] files...

DESCRIPTION
       This page describes the elvis version of ctags.

       ctags generates the "tags" and "refs" files from a group of C source
       files.  The "tags" file is used by Elvis' ":tag" command, ^] command,
       and -t option.  The "refs" file is sometimes used by the ref(1)
       program.

       Each C source file is scanned for #define statements and global
       function definitions.  The name of the macro or function becomes the
       name of a tag.  For each tag, a line is added to the "tags" file.

       The filenames list will typically be the names of all C source files in
       the current directory, like this:

              $ ctags *.c *.h

OPTIONS
       If no options are given, then ctags acts as though the -l -i -t -v and
       -s option flags were given.  If you want to omit those options, you can
       do so by explicitly giving a harmless option such as -F.

       -Dword This causes elvis to ignore any instance of word in your source
              code.  This is handy if you're using a macro for conditionally
              declaring the arguments to functions, in order to make your code
              be backward-compatible with older K&R C compilers.  ctags always
              ignores "P_" and "__P"; the -Dword flag allows you to make it
              ignore a third word.

       -F     Enclose regular expressions in slashes (/regexp/) which will
              cause elvis(1) to search form the top of the file.  This is the
              default.

       -B     Enclose the regular expressions in question marks (?regexp?) so
              elvis(1) will search backward from the bottom of the file.  The
              search direction rarely matters; this option exists mostly for
              compatibility with earlier versions of ctags.

       -N     This causes ctags to use line numbers for all tags.  Without
              this flag, it would use numbers for #define'ed macros, and
              regular expressions for anything else.

       -i     Include inline definitions.  A tag will be generated for each
              function which is declared as being inline, __inline, or
              __inline__.

       -t     Include typedefs.  A tag will be generated for each user-defined
              type.  Also tags will be generated for struct and enum names.
              Types are considered to be global if they are defined in a
              header file, and static if they are defined in a C source file.

       -v     Include variable declarations.  A tag will be generated for each
              variable, except for those that are declared inside the body of
              a function.

       -s     Include static tags.  ctags will normally put global tags in the
              "tags" file, and silently ignore the static tags.  This flag
              causes both global and static tags to be added.

       -e     Include extern tags.  ctags will normally ignore extern
              declarations of functions or variables; that's handy when
              generating tags for your own programs.  A tags file for the
              extern declarations in the system's standard header files can be
              a very handy resource, so this -e flag was created.

       -h     Add hints that may help elvis handle overloaded tags better.
              The resulting tags file may be unreadable by programs other than
              elvis, though.

       -l     Add "ln" line number hints.  This implies -h, since it would be
              pointless if hints weren't allowed.  The "ln" hints are used by
              elvis(1) to make its "showtag" option work much faster.

       -p     Write parsing information to stdout.  This is intended mainly as
              an aid to debugging the ctags command itself.  If ctags doesn't
              generate all of the tags that you expect it to, then try
              studying the -p output to determine what syntax feature is
              tripping it up.

       -x     Generate a human-readable tag list instead of a "tags" file.
              The list is written to stdout.  Each line contains a tag name,
              the line number and file name where the tag is defined, and the
              text of that line.

       -r     This causes ctags to generate both "tags" and "refs".  Without
              -r, it would only generate "tags".

       -a     Append to "tags", and maybe "refs".  Normally, ctags overwrites
              these files each time it is invoked.  This flag is useful when
              you have too many files in the current directory for you to list
              them on a single command-line; it allows you to split the
              arguments among several invocations.  This may result in an
              unsorted tags file.

FORMAT OF THE TAGS FILE
       The "tags" file is a text file.  Each line stores the attributes of a
       single tag.  The basic format of a line is:
                     - the name of the tag
                     - a tab character
                     - the name of the file containing the tag
                     - a tab character
                     - the tag's address within that file

       The tag address may be given as either line number (a string of
       digits), or a regular expression using ex/vi's "nomagic" syntax,
       delimited by either slashes or question marks.  Regular expressions are
       allowed to contain tab characters.

       The authors of elvis, vim, and "exuberant" ctags have agreed on a
       standard format for adding additional attributes to tags.  In this
       format, the first three fields of all tags are identical to the
       traditional format, except that a semicolon-doublequote character pair
       is appended to the tag address field, with the extra attributes
       appearing after that.

       The semicolon-doublequote character pair is present because it has the
       surprising side-effect of making the original ex/vi ignore the
       remainder of the line, thus allowing the original ex/vi to read new-
       format tags files.  The original ex/vi will simply ignore the extra
       attributes.

       Any additional attributes are appended to the tag's line.  They may be
       appended in any order.  Each attribute will use the following format:
                   - a tab character
                   - the name of the attribute
                   - a colon character, ':'
                   - the value of the attribute.
       Note that each additional attribute has an explicit name.  Different
       tags files may use totally different names for additional attributes,
       and even within a single file, most tags will use only a subset of the
       possible attributes.  This version of ctags uses the following names:

       file   This attribute is used to mark static tags -- i.e., tags for
              C/C++ functions or variables whose scope is limited to the
              function in which they are defined.  The value is the name of
              the file where it is defined, except that if the file is the
              same as field 2 (and it nearly always is) then the value may be
              given as a zero-length string.

       class  This is used to mark member functions of C++ classes.  The value
              is the class name.  However, currently ctags doesn't do a very
              good job of detecting whether a function is a member function or
              not.

       kind   This attribute's value is a single letter, indicating the
              lexical type of the tagged identifier: f for a function, t for a
              typedef, s for a struct tag, u for a union tag, v for a
              variable, d for a macro definition, or x for an extern
              declaration.

              Note that in the tags file, the "kind:" label is omitted, for
              the sake of compactness.

       ln     This gives the line number where the tag was defined.  It is
              redundant, but it is still somewhat useful because it allows
              elvis(1)'s "showtag" option to work faster.

       The values can only contain tabs if those tabs are converted to the
       '\t' (backslash-t) notation.  Similarly, a newline, carriage return, or
       literal backslash can be given as '\n', '\r', or '\\' respectively.
       For MS-DOS file names, this means the names must use double
       backslashes.  Space characters don't require any special encoding.
       (This doesn't apply to file names in the tagfile field, where names can
       be given without any special encoding.  It only applies to file names
       in extra fields.)

       As a special case, if an extra attribute contains no ':' to delimit the
       name from the value, then the attribute string is assumed to be the
       value of an attribute named "kind".  Usually this will be a single
       letter indicating what type of token the tag represents -- 'f' for
       function, 'v' for variable, and so on.

       Here's an example of a new-format tag:
              bar  foo.c     /^void Foo::bar(int zot)$/;"  class:Foo
       The tagname is "bar", to match its function's name.  The tagfile is
       "foo.c".  The tagaddress is a regular expression containing the whole
       definition line.  Note that a semicolon-doublequote character pair has
       been appended to the tagaddress.  There is only one additional
       attribute, with the name "class" and the value "Foo".

FILES
       tags   A cross-reference that lists each tag name, the name of the
              source file that contains it, and a way to locate a particular
              line in the source file.

       refs   The "refs" file contains the definitions for each tag in the
              "tags" file, and very little else.  This file can be useful, for
              example, when licensing restrictions prevent you from making the
              source code to the standard C library readable by everybody, but
              you still want everybody to know what arguments the library
              functions need.

BUGS
       ctags is sensitive to indenting and line breaks.  Consequently, it
       might not discover all of the tags in a file that is formatted in an
       unusual way.

       The -a flag causes tag files to be appended, but not necessarily
       sorted.  Some programs expect tags files to be sorted, and will
       misbehave if they aren't.  Also, the new format allows a
       "!_TAG_FILE_SORTED" marker near the top of the file to indicate whether
       the file is sorted, but that might not be accurate after new tags are
       appended to the file.  Consequently, you should avoid the use of -a.

       The new standard doesn't specify how overloaded operators are to be
       labelled.  If your C++ source contains a definition of operator+=(),
       then this version of ctags will store a tag named "operator+=".  Other
       versions of ctags could simply use the name "+=".


SEE ALSO
       elvis(1), ref(1)

AUTHOR
       Steve Kirkendall
       kirkenda@cs.pdx.edu



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