INDENT(1L) INDENT(1L)
NAME
indent - changes the appearance of a C program by inserting or deleting whitespace.
SYNOPSIS
indent [options] [input-files]
indent [options] [single-input-file] [-o output-file]
indent --version
DESCRIPTION
This man page is generated from the file indent.texinfo. This is Edition of "The indent Manual", for Indent
Version , last updated .
The indent program can be used to make code easier to read. It can also convert from one style of writing C
to another.
indent understands a substantial amount about the syntax of C, but it also attempts to cope with incomplete
and misformed syntax.
In version 1.2 and more recent versions, the GNU style of indenting is the default.
OPTIONS
-bad, --blank-lines-after-declarations
Force blank lines after the declarations.
See BLANK LINES.
-bap, --blank-lines-after-procedures
Force blank lines after procedure bodies.
See BLANK LINES.
-bbb, --blank-lines-before-block-comments
Force blank lines before block comments.
See BLANK LINES.
-bbo, --break-before-boolean-operator
Prefer to break long lines before boolean operators.
See BREAKING LONG LINES.
-bc, --blank-lines-after-commas
Force newline after comma in declaration.
See DECLARATIONS.
-bl, --braces-after-if-line
Put braces on line after if, etc.
See STATEMENTS.
-blf, --braces-after-func-def-line
Put braces on line following function definition line.
See DECLARATIONS.
-blin, --brace-indentn
Indent braces n spaces.
See STATEMENTS.
-bls, --braces-after-struct-decl-line
Put braces on struct declaration line.
See DECLARATIONS.
-bs, --Bill-Shannon, --blank-before-sizeof
Put a space between sizeof and its argument.
See STATEMENTS.
-cn, --comment-indentationn
Put comments to the right of code in column n.
See COMMENTS.
-cbin, --case-brace-indentationn
Indent braces after a case label N spaces.
See STATEMENTS.
-cdn, --declaration-comment-columnn
Put comments to the right of the declarations in column n.
See COMMENTS.
-cdb, --comment-delimiters-on-blank-lines
Put comment delimiters on blank lines.
See COMMENTS.
-cdw, --cuddle-do-while
Cuddle while of do {} while; and preceding ‘}’.
See COMMENTS.
-ce, --cuddle-else
Cuddle else and preceding ‘}’.
See COMMENTS.
-cin, --continuation-indentationn
Continuation indent of n spaces.
See STATEMENTS.
-clin, --case-indentationn
Case label indent of n spaces.
See STATEMENTS.
-cpn, --else-endif-columnn
Put comments to the right of #else and #endif statements in column n.
See COMMENTS.
-cs, --space-after-cast
Put a space after a cast operator.
See STATEMENTS.
-dn, --line-comments-indentationn
Set indentation of comments not to the right of code to n spaces.
See COMMENTS.
-bfda, --break-function-decl-args
Break the line before all arguments in a declaration.
See DECLARATIONS.
-fc1, --format-first-column-comments
Format comments in the first column.
See COMMENTS.
-fca, --format-all-comments
Do not disable all formatting of comments.
See COMMENTS.
-gnu, --gnu-style
Use GNU coding style. This is the default.
See COMMON STYLES.
-hnl, --honour-newlines
Prefer to break long lines at the position of newlines in the input.
See BREAKING LONG LINES.
-in, --indent-leveln
Set indentation level to n spaces.
See INDENTATION.
-iln, --indent-labeln
Set offset for labels to column n.
See INDENTATION.
-ipn, --parameter-indentationn
Indent parameter types in old-style function definitions by n spaces.
See INDENTATION.
-kr, --k-and-r-style
Use Kernighan & Ritchie coding style.
See COMMON STYLES.
-ln, --line-lengthn
Set maximum line length for non-comment lines to n.
See BREAKING LONG LINES.
-lcn, --comment-line-lengthn
Set maximum line length for comment formatting to n.
See COMMENTS.
-linux, --linux-style
Use Linux coding style.
See COMMON STYLES.
-lp, --continue-at-parentheses
Line up continued lines at parentheses.
See INDENTATION.
-lps, --leave-preprocessor-space
Leave space between ‘#’ and preprocessor directive.
See INDENTATION.
-nlps, --remove-preprocessor-space
Do not prefer to break long lines before boolean operators.
See BREAKING LONG LINES.
-nbc, --no-blank-lines-after-commas
Do not force newlines after commas in declarations.
See DECLARATIONS.
-nbfda, --dont-break-function-decl-args
Don’t put each argument in a function declaration on a separate line.
See DECLARATIONS.
-ncdb, --no-comment-delimiters-on-blank-lines
Do not put comment delimiters on blank lines.
See COMMENTS.
-ncdw, --dont-cuddle-do-while
Do not cuddle } and the while of a do {} while;.
See STATEMENTS.
-nce, --dont-cuddle-else
Do not cuddle } and else.
See STATEMENTS.
-ncs, --no-space-after-casts
Do not put a space after cast operators.
See STATEMENTS.
-ndjn, --dont-left-justify-declarations
Comments after declarations are treated the same as comments after other statements.
See DECLARATIONS.
-nfc1, --dont-format-first-column-comments
Do not format comments in the first column as normal.
See COMMENTS.
-nfca, --dont-format-comments
Do not format any comments.
See COMMENTS.
-nhnl, --ignore-newlines
Do not prefer to break long lines at the position of newlines in the input.
See BREAKING LONG LINES.
-nip, --no-parameter-indentation
Zero width indentation for parameters.
See INDENTATION.
-nlp, --dont-line-up-parentheses
Do not line up parentheses.
See STATEMENTS.
-npcs, --no-space-after-function-call-names
Do not put space after the function in function calls.
See STATEMENTS.
-nsai, --no-space-after-if
Do not put a space after every if.
See STATEMENTS.
-nsaw, --no-space-after-while
Do not put a space after every while.
See STATEMENTS.
-nsc, --dont-star-comments
Do not put the ‘*’ character at the left of comments.
See COMMENTS.
-nsob, --leave-optional-blank-lines
Do not swallow optional blank lines.
See BLANK LINES.
-nss, --dont-space-special-semicolon
Do not force a space before the semicolon after certain statements. Disables ‘-ss’.
See STATEMENTS.
-nut, --no-tabs
Use spaces instead of tabs.
See INDENTATION.
-nv, --no-verbosity
Disable verbose mode.
See MISCELLANEOUS OPTIONS.
-orig, --original
Use the original Berkeley coding style.
See COMMON STYLES.
-npro, --ignore-profile
Do not read ‘.indent.pro’ files.
See INVOKING INDENT.
-pcs, --space-after-procedure-calls
Insert a space between the name of the procedure being called and the ‘(’.
See STATEMENTS.
-pin, --paren-indentationn
Specify the extra indentation per open parentheses ’(’ when a statement is broken.See STATEMENTS.
-pmt, --preserve-mtime
Preserve access and modification times on output files.See MISCELLANEOUS OPTIONS.
-ppin, --preprocessor-indentationn
Specify the indentation for preprocessor conditional statements.See INDENTATION.
-prs, --space-after-parentheses
Put a space after every ’(’ and before every ’)’.
See STATEMENTS.
-saw, --space-after-while
Put a space after each while.
See STATEMENTS.
-sbin, --struct-brace-indentationn
Indent braces of a struct, union or enum N spaces.
See STATEMENTS.
-sc, --start-left-side-of-comments
Put the ‘*’ character at the left of comments.
See COMMENTS.
-sob, --swallow-optional-blank-lines
Swallow optional blank lines.
See BLANK LINES.
-ss, --space-special-semicolon
On one-line for and while statements, force a blank before the semicolon.
See STATEMENTS.
-st, --standard-output
Write to standard output.
See INVOKING INDENT.
-T Tell indent the name of typenames.
See DECLARATIONS.
-tsn, --tab-sizen
Set tab size to n spaces.
See INDENTATION.
-ut, --use-tabs
Use tabs. This is the default.
See INDENTATION.
-v, --verbose
Enable verbose mode.
See MISCELLANEOUS OPTIONS.
-version
Output the version number of indent.
See MISCELLANEOUS OPTIONS.
INVOKING INDENT
As of version 1.3, the format of the indent command is:
indent [options] [input-files]
indent [options] [single-input-file] [-o output-file]
This format is different from earlier versions and other versions of indent.
fied, then the standard input is read.
As an example, each of the following commands will input the program ‘slithy_toves.c’ and write its indented
text to ‘slithy_toves.out’:
indent slithy_toves.c -o slithy_toves.out
indent -st slithy_toves.c > slithy_toves.out
cat slithy_toves.c | indent -o slithy_toves.out
Most other options to indent control how programs are formatted. As of version 1.2, indent also recognizes a
long name for each option name. Long options are prefixed by either ‘--’ or ‘+’. [ ‘+’ is being superseded
by ‘--’ to maintain consistency with the POSIX standard.]
In most of this document, the traditional, short names are used for the sake of brevity. See OPTION SUMMARY,
for a list of options, including both long and short names.
Here is another example:
indent -br test/metabolism.c -l85
This will indent the program ‘test/metabolism.c’ using the ‘-br’ and ‘-l85’ options, write the output back to
‘test/metabolism.c’, and write the original contents of ‘test/metabolism.c’ to a backup file in the directory
‘test’.
Equivalent invocations using long option names for this example would be:
indent --braces-on-if-line --line-length185 test/metabolism.c
indent +braces-on-if-line +line-length185 test/metabolism.c
If you find that you often use indent with the same options, you may put those options into a file named
‘.indent.pro’. indent will look for a profile file in three places. First it will check the environment vari‐
able INDENT_PROFILE. If that exists its value is expected to name the file that is to be used. If the environ‐
ment variable does not exist, indent looks for ‘.indent.pro’ in the current directory
and use that if found. Finally indent will search your home directory for ‘.indent.pro’ and use that file if
it is found. This behaviour is different from that of other versions of indent, which load both files if they
both exist.
The format of ‘.indent.pro’ is simply a list of options, just as they would appear on the command line, sepa‐
rated by white space (tabs, spaces, and newlines). Options in ‘.indent.pro’ may be surrounded by C or C++
comments, in which case they are ignored.
Command line switches are handled after processing ‘.indent.pro’. Options specified later override arguments
specified earlier, with one exception: Explicitly specified options always override background options (See
COMMON STYLES). You can prevent indent from reading an ‘.indent.pro’ file by specifying the ‘-npro’ option.
BACKUP FILES
As of version 1.3, GNU indent makes GNU-style backup files, the same way GNU Emacs does. This means that
necessary. For instance, setting this variable to "2" will lead to the backup file being named
‘momeraths.c.~04~’.
The type of backup file made is controlled by the value of the environment variable VERSION_CONTROL. If it is
the string ‘simple’, then only simple backups will be made. If its value is the string ‘numbered’, then num‐
bered backups will be made. If its value is ‘numbered-existing’, then numbered backups will be made if there
already exist numbered backups for the file being indented; otherwise, a simple backup is made. If VER‐
SION_CONTROL is not set, then indent assumes the behaviour of ‘numbered-existing’.
Other versions of indent use the suffix ‘.BAK’ in naming backup files. This behaviour can be emulated by set‐
ting SIMPLE_BACKUP_SUFFIX to ‘.BAK’.
Note also that other versions of indent make backups in the current directory, rather than in the directory of
the source file as GNU indent now does.
COMMON STYLES
There are several common styles of C code, including the GNU style, the Kernighan & Ritchie style, and the
original Berkeley style. A style may be selected with a single background option, which specifies a set of
values for all other options. However, explicitly specified options always override options implied by a
background option.
As of version 1.2, the default style of GNU indent is the GNU style. Thus, it is no longer necessary to spec‐
ify the option ‘-gnu’ to obtain this format, although doing so will not cause an error. Option settings which
correspond to the GNU style are:
-nbad -bap -nbc -bbo -bl -bli2 -bls -ncdb -nce -cp1 -cs -di2
-ndj -nfc1 -nfca -hnl -i2 -ip5 -lp -pcs -nprs -psl -saf -sai
-saw -nsc -nsob
The GNU coding style is that preferred by the GNU project. It is the style that the GNU Emacs C mode encour‐
ages and which is used in the C portions of GNU Emacs. (People interested in writing programs for Project GNU
should get a copy of "The GNU Coding Standards", which also covers semantic and portability issues such as
memory usage, the size of integers, etc.)
The Kernighan & Ritchie style is used throughout their well-known book "The C Programming Language". It is
enabled with the ‘-kr’ option. The Kernighan & Ritchie style corresponds to the following set of options:
-nbad -bap -bbo -nbc -br -brs -c33 -cd33 -ncdb -ce -ci4 -cli0
-cp33 -cs -d0 -di1 -nfc1 -nfca -hnl -i4 -ip0 -l75 -lp -npcs
-nprs -npsl -saf -sai -saw -nsc -nsob -nss
Kernighan & Ritchie style does not put comments to the right of code in the same column at all times (nor does
it use only one space to the right of the code), so for this style indent has arbitrarily chosen column 33.
The style of the original Berkeley indent may be obtained by specifying ‘-orig’ (or by specifying ‘--origi‐
nal’, using the long option name). This style is equivalent to the following settings:
-nbad -nbap -bbo -bc -br -brs -c33 -cd33 -cdb -ce -ci4 -cli0
-cp33 -di16 -fc1 -fca -hnl -i4 -ip4 -l75 -lp -npcs -nprs -psl
-saf -sai -saw -sc -nsob -nss -ts8
The Linux style is used in the linux kernel code and drivers. Code generally has to follow the Linux coding
style to be accepted. This style is equivalent to the following settings:
The ‘-bap’ option forces a blank line after every procedure body. The ‘-nbap’ option forces no such blank
line.
The ‘-bbb’ option forces a blank line before every boxed comment (See COMMENTS.) The ‘-nbbb’ option does not
force such blank lines.
The ‘-sob’ option causes indent to swallow optional blank lines (that is, any optional blank lines present in
the input will be removed from the output). If the ‘-nsob’ is specified, any blank lines present in the input
file will be copied to the output file.
--blank-lines-after-declarations
The ‘-bad’ option forces a blank line after every block of declarations. The ‘-nbad’ option does not add any
such blank lines.
For example, given the input
char *foo;
char *bar;
/* This separates blocks of declarations. */
int baz;
indent -bad produces
char *foo;
char *bar;
/* This separates blocks of declarations. */
int baz;
and indent -nbad produces
char *foo;
char *bar;
/* This separates blocks of declarations. */
int baz;
--blank-lines-after-procedures
The ‘-bap’ option forces a blank line after every procedure body.
For example, given the input
int
foo ()
{
puts("Hi");
}
/* The procedure bar is even less interesting. */
char *
bar ()
{
puts("Hello");
bar ()
{
puts ("Hello");
}
and indent -nbap produces
int
foo ()
{
puts ("Hi");
}
/* The procedure bar is even less interesting. */
char *
bar ()
{
puts ("Hello");
}
No blank line will be added after the procedure foo.
COMMENTS
indent formats both C and C++ comments. C comments are begun with ‘/*’, terminated with ‘*/’ and may contain
newline characters. C++ comments begin with the delimiter ‘//’ and end at the newline.
indent handles comments differently depending upon their context. indent attempts to distinguish between com‐
ments which follow statements, comments which follow declarations, comments following preprocessor directives,
and comments which are not preceded by code of any sort, i.e., they begin the text of the line (although not
necessarily in column 1).
indent further distinguishes between comments found outside of procedures and aggregates, and those found
within them. In particular, comments beginning a line found within a procedure will be indented to the column
at which code is currently indented. The exception to this is a comment beginning in the leftmost column;
such a comment is output at that column.
indent attempts to leave boxed comments unmodified. The general idea of such a comment is that it is enclosed
in a rectangle or ‘‘box’’ of stars or dashes to visually set it apart. More precisely, boxed comments are
defined as those in which the initial ‘/*’ is followed immediately by the character ‘*’, ‘=’, ‘_’, or ‘-’, or
those in which the beginning comment delimiter (‘/*’) is on a line by itself, and the following line begins
with a ‘*’ in the same column as the star of the opening delimiter.
Examples of boxed comments are:
/**********************
* Comment in a box!! *
**********************/
/*
* A different kind of scent,
* for a different kind of comment.
*/
indent attempts to leave boxed comments exactly as they are found in the source file. Thus the indentation of
The right margin for formatting defaults to 78, but may be changed with the ‘-lc’ option. If the margin spec‐
ified does not allow the comment to be printed, the margin will be automatically extended for the duration of
that comment. The margin is not respected if the comment is not being formatted.
If the comment begins a line (i.e., there is no program text to its left), it will be indented to the column
it was found in unless the comment is within a block of code. In that case, such a comment will be aligned
with the indented code of that block (unless the comment began in the first column). This alignment may be
affected by the ‘-d’ option, which specifies an amount by which such comments are moved to the left, or unin‐
dented. For example, ‘-d2’ places comments two spaces to the left of code. By default, comments are aligned
with code, unless they begin in the first column, in which case they are left there by default --- to get them
aligned with the code, specify ‘-fc1’.
Comments to the right of code will appear by default in column 33. This may be changed with one of three
options. ‘-c’ will specify the column for comments following code, ‘-cd’ specifies the column for comments
following declarations, and ‘-cp’ specifies the column for comments following preprocessor directives #else
and #endif. ‘-dj’ together with ‘-cd0’ can be used to suppress alignment of comments to the right of declara‐
tions, causing the comment to follow one tabstop from the end of the declaration. Normally ‘-cd0’ causes ‘-c’
to become effective.
If the code to the left of the comment exceeds the beginning column, the comment column will be extended to
the next tabstop column past the end of the code, or in the case of preprocessor directives, to one space past
the end of the directive. This extension lasts only for the output of that particular comment.
The ‘-cdb’ option places the comment delimiters on blank lines. Thus, a single line comment like /* Loving
hug */ can be transformed into:
/*
Loving hug
*/
Stars can be placed at the beginning of multi-line comments with the ‘-sc’ option. Thus, the single-line com‐
ment above can be transformed (with ‘-cdb -sc’) into:
/*
* Loving hug
*/
STATEMENTS
The ‘-br’ or ‘-bl’ option specifies how to format braces.
The ‘-br’ option formats statement braces like this:
if (x > 0) {
x--;
}
The ‘-bl’ option formats them like this:
if (x > 0)
{
x--;
}
if (x > 0) {
x--;
} else {
fprintf (stderr, "...something wrong?\n");
}
With ‘-br -nce’ that code would appear as
if (x > 0) {
x--;
}
else {
fprintf (stderr, "...something wrong?\n");
}
This causes the while in a do-while loop to cuddle up to the immediately preceding ‘}’. For example, with
‘-cdw’ you get the following:
do {
x--;
} while (x);
With ‘-ncdw’ that code would appear as
do {
x--;
}
while (x);
The ‘-cli’ option specifies the number of spaces that case labels should be indented to the right of the con‐
taining switch statement.
The default gives code like:
switch (i)
{
case 0:
break;
case 1:
{
++i;
}
default:
break;
}
Using the ‘-cli2’ that would become:
switch (i)
{
case 0:
break;
case 1:
case 0:
break;
case 1:
{
++i;
}
default:
break;
}
If a semicolon is on the same line as a for or while statement, the ‘-ss’ option will cause a space to be
placed before the semicolon. This emphasizes the semicolon, making it clear that the body of the for or while
statement is an empty statement. ‘-nss’ disables this feature.
The ‘-pcs’ option causes a space to be placed between the name of the procedure being called and the ‘(’ (for
example, puts ("Hi");. The ‘-npcs’ option would give puts("Hi");).
If the ‘-cs’ option is specified, indent puts a space between a cast operator and the object to be cast. The
‘-ncs’ ensures that there is no space between the cast operator and the object. Remember that indent only
knows about the standard C data types and so cannot recognise user-defined types in casts. Thus (mytype)thing
is not treated as a cast.
The ‘-bs’ option ensures that there is a space between the keyword sizeof and its argument. In some versions,
this is known as the ‘Bill_Shannon’ option.
The ‘-saf’ option forces a space between a for and the following parenthesis. This is the default.
The ‘-sai’ option forces a space between a if and the following parenthesis. This is the default.
The ‘-saw’ option forces a space between a while and the following parenthesis. This is the default.
The ‘-prs’ option causes all parentheses to be separated with a space from whatever is between them. For
example, using ‘-prs’ results in code like:
while ( ( e_code - s_code ) < ( dec_ind - 1 ) )
{
set_buf_break ( bb_dec_ind );
*e_code++ = ’ ’;
}
DECLARATIONS
By default indent will line up identifiers, in the column specified by the ‘-di’ option. For example, ‘-di16’
makes things look like:
int foo;
char *bar;
Using a small value (such as one or two) for the ‘-di’ option can be used to cause the identifiers to be
placed in the first available position; for example:
int foo;
char *bar;
With the ‘-nbc’ option this would look like
int a, b, c;
The ‘-bfda’ option causes a newline to be forced after the comma separating the arguments of a function decla‐
ration. The arguments will appear at one indention level deeper than the function declaration. This is par‐
ticularly helpful for functions with long argument lists. The option ‘-bfde’ causes a newline to be forced
before the closing bracket of the function declaration. For both options the ’n’ setting is the default:
-nbdfa and -nbdfe.
For example,
void foo (int arg1, char arg2, int *arg3, long arg4, char arg5);
With the ‘-bfda’ option this would look like
void foo (
int arg1,
char arg2,
int *arg3,
long arg4,
char arg5);
With, in addition, the ‘-bfde’ option this would look like
void foo (
int arg1,
char arg2,
int *arg3,
long arg4,
char arg5
);
The ‘-psl’ option causes the type of a procedure being defined to be placed on the line before the name of the
procedure. This style is required for the etags program to work correctly, as well as some of the c-mode
functions of Emacs.
You must use the ‘-T’ option to tell indent the name of all the typenames in your program that are defined by
typedef. ‘-T’ can be specified more than once, and all names specified are used. For example, if your pro‐
gram contains
typedef unsigned long CODE_ADDR;
typedef enum {red, blue, green} COLOR;
you would use the options ‘-T CODE_ADDR -T COLOR’.
The ‘-brs’ or ‘-bls’ option specifies how to format braces in struct declarations. The ‘-brs’ option formats
braces like this:
struct foo {
int x;
};
int one(void) {
return 1;
};
The ‘-blf’ option formats them like this:
int one(void)
{
return 1;
};
INDENTATION
One issue in the formatting of code is how far each line should be indented from the left margin. When the
beginning of a statement such as if or for is encountered, the indentation level is increased by the value
specified by the ‘-i’ option. For example, use ‘-i8’ to specify an eight character indentation for each
level. When a statement is broken across two lines, the second line is indented by a number of additional
spaces specified by the ‘-ci’ option. ‘-ci’ defaults to 0. However, if the ‘-lp’ option is specified, and a
line has a left parenthesis which is not closed on that line, then continuation lines will be lined up to
start at the character position just after the left parenthesis. This processing also applies to ‘[’ and
applies to ‘{’ when it occurs in initialization lists. For example, a piece of continued code might look like
this with ‘-nlp -ci3’ in effect:
p1 = first_procedure (second_procedure (p2, p3),
third_procedure (p4, p5));
With ‘-lp’ in effect the code looks somewhat clearer:
p1 = first_procedure (second_procedure (p2, p3),
third_procedure (p4, p5));
When a statement is broken in between two or more paren pairs (...), each extra pair causes the indentation
level extra indentation:
if ((((i < 2 &&
k > 0) || p == 0) &&
q == 1) ||
n = 0)
The option ‘-ipN’ can be used to set the extra offset per paren. For instance, ‘-ip0’ would format the above
as:
if ((((i < 2 &&
k > 0) || p == 0) &&
q == 1) ||
n = 0)
indent assumes that tabs are placed at regular intervals of both input and output character streams. These
intervals are by default 8 columns wide, but (as of version 1.2) may be changed by the ‘-ts’ option. Tabs are
treated as the equivalent number of spaces.
The indentation of type declarations in old-style function definitions is controlled by the ‘-ip’ parameter.
This is a numeric parameter specifying how many spaces to indent type declarations. For example, the default
ANSI C allows white space to be placed on preprocessor command lines between the character ‘#’ and the command
name. By default, indent removes this space, but specifying the ‘-lps’ option directs indent to leave this
space unmodified. The option ‘-ppi’ overrides ‘-nlps’ and ‘-lps’.
This option can be used to request that preprocessor conditional statements can be indented by to given number
of spaces, for example with the option ‘-ppi 3’
#if X
#if Y
#define Z 1
#else
#define Z 0
#endif
#endif
becomes
#if X
# if Y
# define Z 1
# else
# define Z 0
# endif
#endif
This option sets the offset at which a label (except case labels) will be positioned. If it is set to zero or
a positive number, this indicates how far from the left margin to indent a label. If it is set to a negative
number, this indicates how far back from the current indent level to place the label. The default setting is
-2 which matches the behaviour of earlier versions of indent. Note that this parameter does not affect the
placing of case labels; see the ‘-cli’ parameter for that. For example with the option ‘-il 1’
group
function()
{
if (do_stuff1() == ERROR)
goto cleanup1;
if (do_stuff2() == ERROR)
goto cleanup2;
return SUCCESS;
cleanup2:
do_cleanup2();
cleanup1:
do_cleanup1();
return ERROR;
}
becomes
group
function()
{
if (do_stuff1() == ERROR)
return ERROR;
}
BREAKING LONG LINES
With the option ‘-ln’, or ‘--line-lengthn’, it is possible to specify the maximum length of a line of C code,
not including possible comments that follow it.
When lines become longer than the specified line length, GNU indent tries to break the line at a logical
place. This is new as of version 2.1 however and not very intelligent or flexible yet.
Currently there are two options that allow one to interfere with the algorithm that determines where to break
a line.
The ‘-bbo’ option causes GNU indent to prefer to break long lines before the boolean operators && and ||. The
‘-nbbo’ option causes GNU indent not have that preference. For example, the default option ‘-bbo’ (together
with ‘--line-length60’ and ‘--ignore-newlines’) makes code look like this:
if (mask
&& ((mask[0] == ’\0’)
|| (mask[1] == ’\0’
&& ((mask[0] == ’0’) || (mask[0] == ’*’)))))
Using the option ‘-nbbo’ will make it look like this:
if (mask &&
((mask[0] == ’\0’) ||
(mask[1] == ’\0’ &&
((mask[0] == ’0’) || (mask[0] == ’*’)))))
The default ‘-hnl’, however, honours newlines in the input file by giving them the highest possible priority
to break lines at. For example, when the input file looks like this:
if (mask
&& ((mask[0] == ’\0’)
|| (mask[1] == ’\0’ && ((mask[0] == ’0’) || (mask[0] == ’*’)))))
then using the option ‘-hnl’, or ‘--honour-newlines’, together with the previously mentioned ‘-nbbo’ and
‘--line-length60’, will cause the output not to be what is given in the last example but instead will prefer
to break at the positions where the code was broken in the input file:
if (mask
&& ((mask[0] == ’\0’)
|| (mask[1] == ’\0’ &&
((mask[0] == ’0’) || (mask[0] == ’*’)))))
The idea behind this option is that lines which are too long, but are already broken up, will not be touched
by GNU indent. Really messy code should be run through indent at least once using the ‘--ignore-newlines’
option though.
DISABLING FORMATTING
Formatting of C code may be disabled for portions of a program by embedding special control comments in the
tion. Thus, for example, turning off formatting in the middle of a function and continuing it after the end
of the function may lead to bizarre results. It is therefore wise to be somewhat modular in selecting code to
be left unformatted.
As a historical note, some earlier versions of indent produced error messages beginning with *INDENT**. These
versions of indent were written to ignore any input text lines which began with such error messages. I have
removed this incestuous feature from GNU indent.
MISCELLANEOUS OPTIONS
To find out what version of indent you have, use the command indent -version. This will report the version
number of indent, without doing any of the normal processing.
The ‘-v’ option can be used to turn on verbose mode. When in verbose mode, indent reports when it splits one
line of input into two more more lines of output, and gives some size statistics at completion.
The ‘-pmt’ option causes indent to preserve the access and modification times on the output files. Using this
option has the advantage that running indent on all source and header files in a project won’t cause make to
rebuild all targets. This option is only available on Operating Systems that have the POSIX utime(2) func‐
tion.
BUGS
Please report any bugs to [email protected].
When indent is run twice on a file, with the same profile, it should never change that file the second time.
With the current design of indent, this can not be guaranteed, and it has not been extensively tested.
indent does not understand C. In some cases this leads to the inability to join lines. The result is that
running a file through indent is irreversible, even if the used input file was the result of running indent
with a given profile (‘.indent.pro’).
While an attempt was made to get indent working for C++, it will not do a good job on any C++ source except
the very simplest.
indent does not look at the given ‘--line-length’ option when writing comments to the output file. This
results often in comments being put far to the right. In order to prohibit indent from joining a broken line
that has a comment at the end, make sure that the comments start on the first line of the break.
indent does not count lines and comments (see the ‘-v’ option) when indent is turned off with /* *INDENT-OFF*
*/.
Comments of the form /*UPPERCASE*/ are not treated as comment but as an identifier, causing them to be joined
with the next line. This renders comments of this type useless, unless they are embedded in the code to begin
with.
COPYRIGHT
The following copyright notice applies to the indent program. The copyright and copying permissions for this
manual appear near the beginning of ‘indent.texinfo’ and ‘indent.info’, and near the end of ‘indent.1’.
Copyright (c) 2001 David Ingamells.
Copyright (c) 1999 Carlo Wood.
Copyright (c) 1995, 1996 Joseph Arceneaux.
Urbana, and Sun Microsystems, Inc. The name of either University
or Sun Microsystems may not be used to endorse or promote products
derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED ‘‘AS IS’’ AND WITHOUT ANY EXPRESS OR
IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
PURPOSE.
Options’ Cross Key
Here is a list of options alphabetized by long option, to help you find the corresponding short option.
--blank-lines-after-commas -bc
--blank-lines-after-declarations -bad
--blank-lines-after-procedures -bap
--blank-lines-before-block-comments -bbb
--braces-after-if-line -bl
--braces-after-func-def-line -blf
--brace-indent -bli
--braces-after-struct-decl-line -bls
--braces-on-if-line -br
--braces-on-func-def-line -brf
--braces-on-struct-decl-line -brs
--break-after-boolean-operator -nbbo
--break-before-boolean-operator -bbo
--break-function-decl-args -bfda
--break-function-decl-args-end -bfde
--case-indentation -clin
--case-brace-indentation -cbin
--comment-delimiters-on-blank-lines -cdb
--comment-indentation -cn
--continuation-indentation -cin
--continue-at-parentheses -lp
--cuddle-do-while -cdw
--cuddle-else -ce
--declaration-comment-column -cdn
--declaration-indentation -din
--dont-break-function-decl-args -nbfda
--dont-break-function-decl-args-end -nbfde
--dont-break-procedure-type -npsl
--dont-cuddle-do-while -ncdw
--dont-cuddle-else -nce
--dont-format-comments -nfca
--dont-format-first-column-comments -nfc1
--dont-line-up-parentheses -nlp
--dont-left-justify-declarations -ndj
--dont-space-special-semicolon -nss
--dont-star-comments -nsc
--else-endif-column -cpn
--format-all-comments -fca
--format-first-column-comments -fc1
--gnu-style -gnu
--honour-newlines -hnl
--no-blank-lines-after-declarations -nbad
--no-blank-lines-after-procedures -nbap
--no-blank-lines-before-block-comments -nbbb
--no-comment-delimiters-on-blank-lines -ncdb
--no-space-after-casts -ncs
--no-parameter-indentation -nip
--no-space-after-for -nsaf
--no-space-after-function-call-names -npcs
--no-space-after-if -nsai
--no-space-after-parentheses -nprs
--no-space-after-while -nsaw
--no-tabs -nut
--no-verbosity -nv
--original -orig
--parameter-indentation -ipn
--paren-indentation -pin
--preserve-mtime -pmt
--preprocessor-indentation -ppin
--procnames-start-lines -psl
--remove-preprocessor-space -nlps
--space-after-cast -cs
--space-after-for -saf
--space-after-if -sai
--space-after-parentheses -prs
--space-after-procedure-calls -pcs
--space-after-while -saw
--space-special-semicolon -ss
--standard-output -st
--start-left-side-of-comments -sc
--struct-brace-indentation -sbin
--swallow-optional-blank-lines -sob
--tab-size -tsn
--use-tabs -ut
--verbose -v
RETURN VALUE
Unknown
FILES
$HOME/.indent.pro holds default options for indent.
AUTHORS
Carlo Wood
Joseph Arceneaux
Jim Kingdon
David Ingamells
HISTORY
Derived from the UCB program "indent".
COPYING
Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996 Free Software Foundation, Inc. Copyright (C) 1995, 1996
Joseph Arceneaux. Copyright (C) 1999 Carlo Wood. Copyright (C) 2001 David Ingamells.
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