ctags(C)

Syntax

Description

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 tags file, vi can quickly locate these object definitions. Depending on the options provided to ctags, the tagged objects will consist of subroutines, and typedef, #define, struct, enum, and union statements.

ctags takes the following options:

-a

Append to an existing tags file.

-B

Use backward searching patterns (?pattern?).

-d

Create tags for #define cpp(CP) macro statements that do not take arguments (this option is always active for XPG4 compatibility).

-f tagsfile

Place the tag descriptions in a file specified by the argument tagsfile. The default behavior is to place them in a file named tags in the current working directory.

-F

Use forward searching patterns (/pattern/) (this is the default).

-t

Create tags for typedefs, structs, unions, and enums (this option is always active for XPG4 compatibility).

-u

Update the specified files in the tags file, that is, all references to them are deleted, and the new values are appended to the file. (Note that this option is rather slow; it is usually faster to rebuild the tags file instead.)

-v

Print a list on the standard output containing the object name, file name, and page number (assuming 64 line pages). Since the output will be sorted into lexicographic order, it may be piped through sort(C).

-w

Suppress warning diagnostics.

-x

Prints a list of object names, the line number and file name on which each is defined together with the text of the line on the standard output. This is a simple index which can be printed out as an offline readable function index.

Files whose names end in .y are assumed to be yacc source files.

Files whose names end in .l are assumed to be LISP files if their first non-blank character is ``;'', ``('', or ``['', 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.

The tag main is treated specially for 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 practical in directories with more than one program.

yacc and lex files each have a special tag; yyparse is the start of the second section of the yacc file, and yylex is the start of the second section of the lex file.

Exit values

Limitations

ctags does not understand Pascal types.

The algorithm which looks for C, Pascal or FORTRAN functions is not completely foolproof. ctags relies on its input being well formed; any syntactical errors will confuse it.

ctags finds the syntax of some cpp conditional compilation statements confusing. For example, since ctags does not understand #ifdef statements, any code with unbalanced braces inside such statements will cause it to become somewhat disoriented. Similarly, multiple lines within #define and typedef statements will cause ctags to enter the last line of the object, rather than the first, as the searching pattern.

Files

/usr/bin/ctags

ctags executable

tags

default output tags file

See also

Standards conformance

ISO/IEC DIS 99452:1992, Information technology Portable Operating System Interface (POSIX) Part 2: Shell and Utilities (IEEE Std 1003.21992);
X/Open CAE Specification, Commands and Utilities, Issue 4, 1992.

ctags was developed at the University of California at Berkeley and is used with permission.