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.\"     @(#)ctags.1	8.1 (Berkeley) 6/6/93
.\" $FreeBSD$
.\"
.Dd June 6, 1993
.Dt CTAGS 1
.Os
.Sh NAME
.Nm ctags
.Nd create a
.Pa tags
file
.Sh SYNOPSIS
.Nm
.Op Fl BFTaduwvx
.Op Fl f Ar tagsfile
.Ar
.Sh DESCRIPTION
The
.Nm
utility makes a
.Pa tags
file for
.Xr ex 1
from the specified C,
Pascal, Fortran,
.Xr yacc 1 ,
.Xr lex 1 ,
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
white-space.
Using the
.Pa tags
file,
.Xr ex 1
can quickly locate these object definitions.
Depending upon the options provided to
.Nm ,
objects will consist of subroutines, typedefs, defines, structs,
enums and unions.
.Pp
The following options are available:
.Bl -tag -width indent
.It Fl B
Use backward searching patterns
.Pq Li ?...? .
.It Fl F
Use forward searching patterns
.Pq Li /.../
(the default).
.It Fl T
Do not create tags for typedefs, structs, unions, and enums.
.It Fl a
Append to
.Pa tags
file.
.It Fl d
Create tags for
.Li #defines
that do not take arguments;
.Li #defines
that take arguments are tagged automatically.
.It Fl f
Place the tag descriptions in a file called
.Ar tagsfile .
The default behaviour is to place them in a file called
.Pa tags .
.It Fl u
Update the specified files in the
.Pa tags
file, 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 which is rather
slow; it is usually faster to simply rebuild the
.Pa tags
file.)
.It Fl v
An index of the form expected by
.Xr vgrind 1
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
.Xr sort 1 .
Sample use:
.Bd -literal -offset indent
ctags -v files | sort -f > index
vgrind -x index
.Ed
.It Fl w
Suppress warning diagnostics.
.It Fl x
.Nm
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.
.El
.Pp
Files whose names end in
.Pa .c
or
.Pa .h
are assumed to be C
source files and are searched for C style routine and macro definitions.
Files whose names end in
.Pa .y
are assumed to be
.Xr yacc 1
source files.
Files whose names end in
.Pa .l
are assumed to be Lisp files if their
first non-blank character is
.Ql \&; ,
.Ql \&( ,
or
.Ql \&[ ,
otherwise, they are
treated as
.Xr lex 1
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.
.Pp
The tag
.Dq Li main
is treated specially in C programs.
The tag formed
is created by prepending
.Ql M
to the name of the file, with the
trailing
.Pa .c
and any leading pathname components removed.
This makes use of
.Nm
practical in directories with more than one
program.
.Pp
The
.Xr yacc 1
and
.Xr lex 1
files each have a special tag.
.Dq Li yyparse
is the start
of the second section of the
.Xr yacc 1
file, and
.Dq Li yylex
is the start of
the second section of the
.Xr lex 1
file.
.Sh FILES
.Bl -tag -width ".Pa tags" -compact
.It Pa tags
default output tags file
.El
.Sh EXIT STATUS
The
.Nm
utility exits with a value of 1 if an error occurred, 0 otherwise.
Duplicate objects are not considered errors.
.Sh COMPATIBILITY
The
.Fl t
option is a no-op for compatibility with previous versions of
.Nm
that did not create tags for typedefs, enums, structs and unions
by default.
.Sh SEE ALSO
.Xr ex 1 ,
.Xr vi 1
.Sh STANDARDS
The
.Nm
utility conforms to
.St -p1003.1-2001 .
.Sh HISTORY
The
.Nm
utility appeared in
.Bx 3.0 .
.Sh BUGS
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
.Nm
utility does not
understand about Pascal types.
.Pp
The method of deciding whether to look for C, Pascal or
Fortran
functions is a hack.
.Pp
The
.Nm
utility 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 does not understand
.Li #ifdef Ns 's
(incidentally, that is a feature, not a bug), any code with unbalanced
braces inside
.Li #ifdef Ns 's
will 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 multiple line
.Li typedef Ns 's
will similarly be noted.