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LINT(1) NetBSD General Commands Manual LINT(1)
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lint -- a C program verifier
lint [-abceFgHhPprTVvwxz] [-i | -nu] [-S | -s | -t | -Ac11 | -Ac23]
[-B directory] [-D name[=def]] [-d directory] [-I directory]
[-L directory] [-MD] [-l library] [-o outputfile] [-q id[,id]...]
[-U name] [-W cppwarnarg] [-X id[,id]...] [-Z cpparg] file ...
lint [-abceFgHhprTVvwz] [-S | -s | -t | -Ac11 | -Ac23] -C library
[-B directory] [-D name[=def]] [-d directory] [-I directory] [-MD]
[-R old=new] [-U name] [-W cppwarnarg] [-X id[,id]...] [-Z cpparg]
lint 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 per-
forms stricter type checking than traditional pre-C90 C compilers. The
list of errors and warnings that lint produces are enumerated in lint(7).
In the first synopsis form, lint checks each given file as a separate
translation unit. In the second synopsis form, lint cross-checks the
results of the first synopsis form for inconsistencies between transla-
lint runs the C preprocessor as its first phase, with the following pre-
processor symbols defined to allow certain questionable code to be
altered or skipped: __LINT__, lint, __lint, __lint__. These symbols
should therefore be thought of as reserved words 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, non-prototype functions called with
varying numbers of arguments, non-prototype function calls that pass
arguments of a type other than the type the function expects to receive,
functions whose return values are not used, and calls to non-prototype
functions not returning values that nevertheless 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. lint also accepts special libraries specified with
the -l option, which contain definitions of library routines and vari-
lint takes all the .c, .ln, and llib-llibrary.ln (lint library) files and
processes them in command-line order. By default, lint appends the stan-
dard 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 ignored. When the -i
option is omitted, the second pass of lint checks this list of files for
mutual compatibility but always exits successfully. 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 ques-
-Ac11 Allow features from C11, C99 and C90.
-Ac23 Allow features from C23, C17, C11, C99 and C90.
-a Report assignments of long values to variables that are not
-aa Additional to -a, report all assignments of integer values
to other integer values which cause implicit narrowing con-
-Bpath Path to use when looking for the lint1 and lint2 binaries.
Defaults to /usr/libexec.
-b Report break statements that cannot be reached. This is
not the default because, unfortunately, most lex(1) and
many yacc(1) outputs produce many such complaints.
-Clibrary Create a lint library with the name llib-llibrary.ln. This
library 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, including libraries specified with the -l
option, for mutual compatibility.
-c Complain about casts which have questionable portability.
-Dname[=def] Define name for cpp(1), as if by a #define directive. If
no definition is given, name is defined as 1.
-ddirectory Use directory as the root directory (DESTDIR) to find
-e Complain about unusual operations on enum types and combi-
nations of enum and integer types.
-F Print pathnames of files, not only the basenames. lint
normally prints the filename without the path.
-g Don't print warnings for some extensions of gcc(1) to the C
language. Currently these are nonconstant initializers in
automatic aggregate initializations, arithmetic on pointer
to void, trailing commas in enum declarations, C++ -style
``//'' comments, 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 (alternative keywords
with leading underscores for both asm and inline are always
-H If a complaint stems from an included file, print the name
of the included file instead of the source file name fol-
lowed by a question mark.
-h Apply a number of heuristic tests to attempt to intuit
bugs, improve style, and reduce waste.
-Idirectory Add directory to the list of directories in which to search
for include files.
-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.
-Ldirectory Search for lint libraries in directory and directory/lint
before searching the standard place.
-llibrary Include the lint library llib-llibrary.ln.
-MD Pass -MD to cpp(1), causing cpp to create files containing
dependency information for each source file.
-n Do not check compatibility against the standard library.
-ooutputfile 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 produce 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.
-P Enable more portability warnings: enum comparisons, sign
extension issues when assigning to wider integer types,
overflow warnings when assigning to wider types.
-p Attempt to check portability of code to other platforms of
In addition to the usual warnings and errors, run the
selected queries, which are listed in lint(7). These
queries are similar to warnings, they do not highlight pos-
sible bugs though, but instead point to other events in the
code that may be interesting to look at on a case-by-case
basis. The most convenient way to run queries on a source
file is to run:
make LINT="lint -q3,5,7" source.ln
To allow this command to be run repeatedly, the option -q
prevents creating the .ln file.
-R old=new Remap old directory prefixes to new for reproducible
-r In case of redeclarations, report the position of the pre-
-S C99 mode. Currently not fully implemented.
-s Strict ISO C90 mode. Issue warnings and errors required by
ISO C90, as opposed to traditional C. Also do not produce
warnings for constructs which behave differently in tradi-
tional C and ISO C90. With the -s flag, __STRICT_ANSI__ is
a predefined preprocessor macro.
-T Treat _Bool as a data type that is incompatible with all
other scalar types.
-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 dif-
ferently in traditional C and C90 are suppressed. Pre-
processor macros describing the machine type (e.g. sun3)
and machine architecture (e.g. m68k) are defined without
leading and trailing underscores. The keywords const,
volatile and signed are not available in traditional C mode
(although the alternative keywords with leading underscores
-Uname Remove any initial definition of name for the preprocessor.
-u Do not complain about functions and external variables used
and not defined, or defined and not used (this is suitable
for running lint on a subset of files comprising part of a
-V Print the command lines constructed by the controller pro-
gram to run the C preprocessor and lint's first and second
-v Suppress complaints about unused parameters in functions.
Pass the warning directive to cpp(1).
-w Treat warnings as errors.
Suppress error messages identified by the list of ids. A
list of messages and ids can be found in lint(7).
-x Report variables referred to by extern declarations, but
-Z cpparg Pass cpparg to cpp(1) directly. Multiple -Z cppargs can be
passed in the order they are received.
-z Do not complain about structures that are never defined
(for example, using a structure pointer without knowing its
lint's first pass reads standard C source files. lint recognizes the
following C comments as commands.
/* ARGSUSEDn */
Makes lint check only the first n parameters for usage; a
missing n is taken to be 0 (this option acts like the -v
option for the next function).
/* BITFIELDTYPE */
Suppress error messages about illegal bitfield types if the
type is an integer type, and suppress non-portable bitfield
/* CONSTCOND */ or /* CONSTANTCOND */ or /* CONSTANTCONDITION */
Suppress complaints about constant operands for the next
/* FALLTHRU */ or /* FALLTHROUGH */
Suppress complaints about fall through to a case or default
labeled statement. This directive should be placed immedi-
ately preceding the label.
/* LINTLIBRARY */
At the beginning of a file, mark all functions and variables
defined in this file as used. Also shut off complaints about
unused function parameters.
/* LINTEDn [comment] */ or /* NOSTRICTn [comment] */
Suppresses any intra-file warning except those dealing with
unused variables or functions. This directive should be
placed on the line immediately preceding where the lint warn-
ing occurred. The optional numeric argument suppresses the
specific numbered message instead of every message. A list
of messages and ids can be found in lint(7).
/* 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 format string that
is used to check the remaining arguments.
/* PROTOLIBn */
Causes lint to treat function declaration prototypes as func-
tion 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 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
option), 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
The lint utility exits 0 on success, and >0 if an error occurs. If the
-w flag is given, warnings are considered errors.
LIBDIR The directory where the lint libraries specified by the
-llibrary option must exist. If this environment variable is
undefined, then the default path /usr/libdata/lint will be
used to search for the libraries.
If set to `yes', or if set to `on-error' and lint exits
unsuccessfully, do no delete the output from the C preproces-
sor, allowing for manual inspection.
TMPDIR Usually the path for temporary files can be redefined by set-
ting this environment variable.
CC Location of the C compiler program. Defaults to /usr/bin/cc.
/usr/libdata/lint/llib-l*.ln various prebuilt lint libraries
lint -i -Sg source.c
Run lint in C99 mode with GNU extensions, with only few
checks, creating source.ln.
lint -i -abcFghprSxz source.c
Run lint with the same checks as in the NetBSD build.
lint -i -Ac11 -g -aabceFhpPrTxz source.c
Run lint in C11 mode with GNU extensions, enabling all
available checks, including lossy conversions on small
integer types, unusual operations on enum types, more
portability warnings, and strict bool mode.
cc(1), cpp(1), make(1), lint(7)
Jochen Pohl (1995)
Roland Illig (2021 to 2023)
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.
NetBSD 10.99 August 2, 2023 NetBSD 10.99