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LINT(1)			  BSD General Commands Manual		       LINT(1)

     lint -- a C program verifier

     lint [-abceghprvxzHFV] [-s	| -t] [-i | -nu] [-D name[=def]] [-U name]
	  [-I directory] [-L directory]	[-l library] [-o outputfile] file ...
     lint [-abceghprvzHFV] [-s | -t] -C	library	[-D name[=def]]	[-I directory]
	  [-U name] file ...

     The lint utility attempts to detect features of the named C program files
     that are likely to	be bugs, to be non-portable, or	to be wasteful.	 It
     also performs stricter type checking than the C compiler.	The lint util-
     ity runs the C preprocessor as its	first phase, with the preprocessor
     symbol "lint" defined to allow certain questionable code to be altered or
     skipped by	lint.  Therefore, this symbol should be	thought	of as a	re-
     served word for all code that is to be checked by lint.

     Among the possible	problems that are currently noted are unreachable
     statements, loops not entered at the top, variables declared and not
     used, and logical expressions with	constant values.  Function calls are
     checked for inconsistencies, such as calls	to functions that return val-
     ues in some places	and not	in others, functions called with varying num-
     bers of arguments,	function calls that pass arguments of a	type other
     than the type the function	expects	to receive, functions whose values are
     not used, and calls to functions not returning values that	use the	non-
     existent return value of the function.

     Filename arguments	ending with .c are taken to be C source	files.	File-
     name arguments with names ending with .ln are taken to be the result of
     an	earlier	invocation of lint, with either	the -i,	-o, or -C option in
     effect.  The .ln files are	analogous to the .o (object) files produced by
     cc(1) from	.c files.  The lint utility also accepts special libraries
     specified with the	-l option, which contain definitions of	library	rou-
     tines and variables.

     The lint utility takes all	the .c,	.ln, and llib-llibrary.ln (lint	li-
     brary) files and processes	them in	command-line order.  By	default, lint
     appends the standard C lint library (llib-lc.ln) to the end of the	list
     of	files.	When the -i option is used, the	.ln files are ignored.	Also,
     when the -o or -i options are used, the llib-llibrary.ln files are	ig-
     nored.  When the -i option	is omitted the second pass of lint checks this
     list of files for mutual compatibility.  At this point, if	a complaint
     stems not from a given source file, but from one of its included files,
     the source	filename will be printed followed by a question	mark.

     The options are as	follows:

     -a	     Report assignments	of long	values to variables that are not long.

     -aa     Additional	to -a, report all assignments of integer values	to
	     other integer values which	cause implicit narrowing conversion.

     -b	     Report break statements that cannot be reached.  This is not the
	     default because, unfortunately, most lex(1) and many yacc(1) out-
	     puts produce many such complaints.

     -c	     Complain about casts which	have questionable portability.

     -e	     Complain about unusual operations on enum-Types and combinations
	     of	enum- and integer-Types.

     -g	     Don't print warnings for some extensions of gcc(1)	to the C lan-
	     guage.  Currently these are nonconstant initializers in automatic
	     aggregate initializations,	arithmetic on pointer to void, zero
	     sized structures, subscripting of non-lvalue arrays, prototypes
	     overriding	old style function declarations	and long long integer
	     types.  The -g flag also turns on the keywords asm	and inline
	     (alternate	keywords with leading underscores for both asm and
	     inline are	always available).

     -h	     Apply a number of heuristic tests to attempt to intuit bugs, im-
	     prove style, and reduce waste.

     -i	     Produce a .ln file	for every .c file on the command line.	These
	     .ln files are the product of lint's first pass only, and are not
	     checked for compatibility between functions.

     -n	     Do	not check compatibility	against	the standard library.

     -p	     Attempt to	check portability of code to other dialects of C.

     -r	     In	case of	redeclarations report the position of the previous

     -s	     Strict ANSI C mode.  Issue	warnings and errors required by	ANSI
	     C.	 Also do not produce warnings for constructs which behave dif-
	     ferently in traditional C and ANSI	C.  With the -s	flag,
	     __STRICT_ANSI__ is	a predefined preprocessor macro.

     -t	     Traditional C mode.  __STDC__ is not predefined in	this mode.
	     Warnings are printed for constructs not allowed in	traditional C.
	     Warnings for constructs which behave differently in traditional C
	     and ANSI C	are suppressed.	 Preprocessor macros describing	the
	     machine type (e.g., sun3) and machine architecture	(e.g., m68k)
	     are defined without leading and trailing underscores.  The	key-
	     words const, volatile and signed are not available	in traditional
	     C mode (although the alternate keywords with leading underscores
	     still are).

     -u	     Do	not complain about functions and external variables used and
	     not defined, or defined and not used (this	is suitable for	run-
	     ning lint on a subset of files comprising part of a larger	pro-

     -v	     Suppress complaints about unused arguments	in functions.

     -x	     Report variables referred to by extern declarations, but never

     -z	     Do	not complain about structures that are never defined (for ex-
	     ample, using a structure pointer without knowing its contents).

     -C	library
	     Create a lint library with	the name llib-llibrary.ln.  This li-
	     brary is built from all .c	and .ln	input files.  After all	global
	     definitions of functions and variables in these files are written
	     to	the newly created library, lint	checks all input files,	in-
	     cluding libraries specified with the -l option, for mutual	com-

     -D	name[=def]
	     Define name for cpp(1), as	if by a	#define	directive.  If no def-
	     inition is	given, name is defined as 1.

     -I	directory
	     Add directory to the list of directories in which to search for
	     include files.

     -l	library
	     Include the lint library llib-llibrary.ln.

     -L	directory
	     Search for	lint libraries in directory and	directory/lint before
	     searching the standard place.

     -F	     Print pathnames of	files.	The lint utility normally prints the
	     filename without the path.

     -H	     If	a complaint stems from an included file	lint prints the	name
	     of	the included file instead of the source	file name followed by
	     a question	mark.

     -o	outputfile
	     Name the output file outputfile.  The output file produced	is the
	     input that	is given to lint's second pass.	 The -o	option simply
	     saves this	file in	the named output file.	If the -i option is
	     also used the files are not checked for compatibility.  To	pro-
	     duce a llib-llibrary.ln without extraneous	messages, use of the
	     -u	option is suggested.  The -v option is useful if the source
	     file(s) for the lint library are just external interfaces.

     -U	name
	     Remove any	initial	definition of name for the preprocessor.

     -V	     Print the command lines constructed by the	controller program to
	     run the C preprocessor and	lint's first and second	pass.

   Input Grammar
     lint's first pass reads standard C	source files.  The lint	utility	recog-
     nizes the following C comments as commands.

     /*	ARGSUSEDn */
	     makes lint	check only the first n arguments for usage; a missing
	     n is taken	to be 0	(this option acts like the -v option for the
	     next function).

	     suppress complaints about constant	operands for the next expres-

     /*	FALLTHRU */ or /* FALLTHROUGH */
	     suppress complaints about fall through to a case or default la-
	     belled statement.	This directive should be placed	immediately
	     preceding the label.

     /*	LINTLIBRARY */
	     At	the beginning of a file, mark all functions and	variables de-
	     fined in this file	as used.  Also shut off	complaints about un-
	     used function arguments.

     /*	LINTED [comment] */ or /* NOSTRICT [comment] */
	     Suppresses	any intra-file warning except those dealing with un-
	     used variables or functions.  This	directive should be placed on
	     the line immediately preceding where the lint warning occurred.

     /*	LONGLONG */
	     Suppress complaints about use of long long	integer	types.

     /*	NOTREACHED */
	     At	appropriate points, inhibit complaints about unreachable code.
	     (This comment is typically	placed just after calls	to functions
	     like exit(3)).

     /*	PRINTFLIKEn */
	     makes lint	check the first	(n-1) arguments	as usual.  The n-th
	     argument is interpreted as	a printf(3) format string that is used
	     to	check the remaining arguments.

     /*	PROTOLIBn */
	     causes lint to treat function declaration prototypes as function
	     definitions if n is non-zero.  This directive can only be used in
	     conjunction with the /* LINTLIBRARY */ directive.	If n is	zero,
	     function prototypes will be treated normally.

     /*	SCANFLIKEn */
	     makes lint	check the first	(n-1) arguments	as usual.  The n-th
	     argument is interpreted as	a scanf(3) format string that is used
	     to	check the remaining arguments.

     /*	VARARGSn */
	     Suppress the usual	checking for variable numbers of arguments in
	     the following function declaration.  The data types of the	first
	     n arguments are checked; a	missing	n is taken to be 0.

     The behavior of the -i and	the -o options allows for incremental use of
     lint on a set of C	source files.  Generally, one invokes lint once	for
     each source file with the -i option.  Each	of these invocations produces
     a .ln file	that corresponds to the	.c file, and prints all	messages that
     are about just that source	file.  After all the source files have been
     separately	run through lint, it is	invoked	once more (without the -i op-
     tion), listing all	the .ln	files with the needed -llibrary	options.  This
     will print	all the	inter-file inconsistencies.  This scheme works well
     with make(1); it allows make(1) to	be used	to lint	only the source	files
     that have been modified since the last time the set of source files were

     LIBDIR  the directory where the lint libraries specified by the
	     -l	library	option must exist.  If this environment	variable is
	     undefined,	then the default path /usr/libdata/lint	will be	used
	     to	search for the libraries.

     TMPDIR  usually the path for temporary files can be redefined by setting
	     this environment variable.

     /usr/libexec/lint[12]	   programs
     /usr/libdata/lint/llib-l*.ln  various prebuilt lint libraries
     /tmp/lint*			   temporaries

     cc(1), cpp(1), make(1)

     Jochen Pohl

     The routines exit(3), longjmp(3) and other	functions that do not return
     are not understood; this causes various incorrect diagnostics.

     Static functions which are	used only before their first extern declara-
     tion are reported as unused.

     Libraries created by the -o option	will, when used	in later lint runs,
     cause certain errors that were reported when the libraries	were created
     to	be reported again, and cause line numbers and file names from the
     original source used to create those libraries to be reported in error
     messages.	For these reasons, it is recommended to	use the	-C option to
     create lint libraries.

BSD				August 28, 1994				   BSD


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