— create a
makes a tags file from the specified C,
Pascal, Fortran, YACC, lex, and Lisp sources. A tags file gives the locations
of specified objects in a group of files. Each line of the tags file contains
the object name, the file in which it is defined, and a search pattern for the
object definition, separated by whitespace.
Using the tags
file, a text editor such as
can quickly locate these
object definitions. Indexed objects include subroutines, typedefs, defines,
structs, enums, and unions.
The options are as follows:
- Append to tags file.
- Use backward searching patterns
- Create tags for
#defines that don't
#defines that take arguments are
- Use forward searching patterns
/.../) (the default).
- Places the tag descriptions in a file called
tagsfile. The default behaviour is to
place them in a file called tags.
- Update the specified files in the
tags file; that is, all references to
them are regenerated, keeping only the other values in the file.
- An index of the form expected by vgrind is produced on the
standard output. This listing contains the object name, file name, and
page number (assuming 64 line pages). Since the output will be sorted into
lexicographic order, it may be desired to run the output through
sort(1). Sample use:
$ ctags -v files | sort -f > index
$ vgrind -x index
- Suppress warning diagnostics.
- ctags produces a list of
object names, the line number and file name on which each is defined, as
well as the text of that line and prints this on the standard output. This
is a simple index which can be printed out as an off-line readable
Files whose names end in “.c” or “.h” are assumed to
be C source files and are searched for C style routine and macro definitions.
Files whose names end in “.y” are assumed to be
source files. Files whose
names end in “.l” are assumed to be Lisp files if their first
non-blank character is ‘
’, otherwise, they are treated as lex
files. Other files are first examined to see if they contain any Pascal or
Fortran routine definitions and, if not, are searched for C style definitions.
is treated specially in C programs. The tag
formed is created by prepending ‘M’ to the name of the file,
with the trailing “.c” and any leading pathname components
removed. This makes use of ctags
directories with more than one program.
Yacc and lex files each have a special tag.
is the start of the second section of
the yacc file, and yylex
is the start of the
second section of the lex file.
- default output tags file
utility exits 0 on success,
and >0 if an error occurs.
Duplicate objects are not considered errors.
utility is compliant with the
IEEE Std 1003.1-2008
specification, though its presence is
The flags [-BdFuvw
extensions to that specification.
Support for Pascal, YACC, lex, and Lisp source files is an
IEEE Std 1003.1-2008
extension. The standard notes that
is “not required to accommodate
these languages, although implementors are encouraged to do so”.
command appeared in
Recognition of functions, subroutines, and procedures for FORTRAN and Pascal is
done in a very simple-minded way. No attempt is made to deal with block
structure; if you have two Pascal procedures in different blocks with the same
name you lose. ctags
doesn't understand about
The method of deciding whether to look for C, Pascal or FORTRAN functions is a
relies on the input being well formed, and
any syntactical errors will completely confuse it. It also finds some legal
syntax confusing; for example, since it doesn't understand
's (incidentally, that's a feature, not a bug),
any code with unbalanced braces inside
cause it to become somewhat disoriented. In a similar fashion, multiple line
changes within a definition will cause it to enter the last line of the
object, rather than the first, as the searching pattern. The last line of
's will similarly be noted.