CTAGS(1HAS) User Commands CTAGS(1HAS)


ctags - create a tags file for use with ex and vi


/usr/bin/ctags [-aBFtuvwx] [-f tagsfile] file...

/usr/xpg4/bin/ctags [-aBFuvwx] [-f tagsfile] file...


The ctags utility makes a tags file for ex(1) from the specified C, C++,
Pascal, FORTRAN, yacc(1), and lex(1) sources. A tags file gives the
locations of specified objects (in this case functions and typedefs) in a
group of files. Each line of the tags file contains the object name, the
file in which it is defined, and an address specification for the object
definition. Functions are searched with a pattern, typedefs with a line
number. Specifiers are given in separate fields on the line, separated
by SPACE or TAB characters. Using the tags file, ex can quickly find
these objects' definitions.

Normally, ctags places the tag descriptions in a file called tags; this
may be overridden with the -f option.

Files with names ending in .c or .h are assumed to be either C or C++
source files and are searched for C/C++ routine and macro definitions.
Files with names ending in .cc, .C, or .cxx are assumed to be C++ source
files. Files with names ending in .y are assumed to be yacc source
files. Files with names ending in .l are assumed to be lex files.
Others are first examined to see if they contain any Pascal or FORTRAN
routine definitions; if not, they are processed again looking for C

The tag main is treated specially in C or C++ programs. The tag formed
is created by prepending M to file, with a trailing .c, .cc, .C, or .cxx
removed, if any, and leading path name components also removed. This
makes use of ctags practical in directories with more than one program.


The precedence of the options that pertain to printing is -x, -v, then
the remaining options. The following options are supported:

Appends output to an existing tags file.

Uses backward searching patterns (?...?).

-f tagsfile
Places the tag descriptions in a file called tagsfile
instead of tags.

Uses forward searching patterns (/.../) (default).

Creates tags for typedefs. /usr/xpg4/bin/ctags creates
tags for typedefs by default.

Updates the specified files in tags, that is, all
references to them are deleted, and the new values are
appended to the file. Beware: this option is implemented
in a way that is rather slow; it is usually faster to
simply rebuild the tags file.

Produces on the standard output an index listing the
function 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 -f.

Suppresses warning diagnostics.

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 function index.


The following file operands are supported:

Files with basenames ending with the .c suffix are treated as
C-language source code.

Files with basenames ending with the .h suffix are treated as
C-language source code.

Files with basenames ending with the .f suffix are treated as
FORTRAN-language source code.


The -v option is mainly used with vgrind which will be part of the
optional BSD Compatibility Package.


Example 1: Producing entries in alphabetical order

Using ctags with the -v option produces entries in an order which may not
always be appropriate for vgrind. To produce results in alphabetical
order, you may want to run the output through sort -f.

example% ctags -v filename.c filename.h | sort -f > index
example% vgrind -x index

Example 2: Building a tags file

To build a tags file for C sources in a directory hierarchy rooted at
sourcedir, first create an empty tags file, and then run find(1)

example% cd sourcedir ; rm -f tags ; touch tags
example% find . \( -name SCCS -prune -name \\
'*.c' -o -name '*.h' \) -exec ctags -u {} \;

Notice that spaces must be entered exactly as shown.


See environ(7) for descriptions of the following environment variables
that affect the execution of ctags: LANG, LC_ALL, LC_COLLATE, LC_CTYPE,


The following exit values are returned:

Successful completion.

An error occurred.


output tags file



|Interface Stability | Standard |


ex(1), lex(1), vgrind(1), vi(1), yacc(1), attributes(7), environ(7),


Recognition of functions, subroutines, and procedures for FORTRAN and
Pascal is done in a very simpleminded 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.

The method of deciding whether to look for C or Pascal and FORTRAN
functions is a hack.

The ctags utility does not know about #ifdefs.

The ctags utility should know about Pascal types. Relies on the input
being well formed to detect typedefs. Use of -tx shows only the last line
of typedefs.

March 18, 1997 CTAGS(1HAS)