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Test Your Knowledge in Computers #202
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At compile time, the interpreter parses Perl code into a recursive flat-space module.
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ctags(1) [osx man page]

CTAGS(1)						    BSD General Commands Manual 						  CTAGS(1)

NAME
ctags -- create a tags file SYNOPSIS
ctags [-BFadtuwvx] [-f tags_file] name ... DESCRIPTION
ctags makes a tags file for ex(1) 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 white-space. Using the tags file, ex(1) can quickly locate these object definitions. Depending upon the options provided to ctags, objects will consist of subroutines, typedefs, defines, structs, enums, and unions. -a append to tags file. -B use backward searching patterns (?...?). -d create tags for #defines that don't take arguments; #defines that take arguments are tagged automatically. -F use forward searching patterns (/.../) (the default). -f Places the tag descriptions in a file called tags_file. The default behavior is to place them in a file called tags. -t create tags for typedefs, structs, unions, and enums. -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. (Beware: this option is implemented in a way which is rather slow; it is usually faster to simply rebuild the tags file.) -v An index of the form expected by vgrind(1) is produced on the standard output. This listing contains the object name, file name, and page number (assuming 64-line pages). Because the output will be sorted into lexicographic order, it may be desirable to run the output through sort(1). Sample use: ctags -v files | sort -f > index vgrind -x index -w suppress warning diagnostics. -x 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 function index which can be printed out for reading off-line. 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 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; if not, they are searched for C-style definitions. The tag main 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 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 sec- ond section of the lex file. FILES
tags default output tags file DIAGNOSTICS
ctags exits with a value of 1 if an error occurred, 0 otherwise. Duplicate objects are not considered to be errors. SEE ALSO
cc(1), ex(1), lex(1), sort(1), vgrind(1), vi(1), yacc(1) BUGS
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 Pascal procedures with the same name in different blocks, you lose. ctags doesn't understand about Pascal types. The method of deciding whether to look for C, Pascal, or FORTRAN functions is a hack. ctags relies on the input being well formed, so any syntactical errors will completely confuse it. It also finds some legal syntax to be confusing; for example, because it doesn't understand #ifdef's (incidentally, that's a feature, not a bug), any code with unbalanced braces inside #ifdef'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 typedef's will simi- larly be noted. HISTORY
The ctags command appeared in 3.0BSD. 4th Berkeley Distribution June 6, 1993 4th Berkeley Distribution

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