coreutils.texi

Linux下文件工具。

line numbers or logical pages between files.

@cindex headers, numbering
@cindex body, numbering
@cindex footers, numbering
A logical page consists of three sections: header, body, and footer.
Any of the sections can be empty.  Each can be numbered in a different
style from the others.

The beginnings of the sections of logical pages are indicated in the
input file by a line containing exactly one of these delimiter strings:

@table @samp
@item \:\:\:
start of header;
@item \:\:
start of body;
@item \:
start of footer.
@end table

The two characters from which these strings are made can be changed from
@samp{\} and @samp{:} via options (see below), but the pattern and
length of each string cannot be changed.

A section delimiter is replaced by an empty line on output.  Any text
that comes before the first section delimiter string in the input file
is considered to be part of a body section, so @command{nl} treats a
file that contains no section delimiters as a single body section.

The program accepts the following options.  Also see @ref{Common options}.

@table @samp

@item -b @var{style}
@itemx --body-numbering=@var{style}
@opindex -b
@opindex --body-numbering
Select the numbering style for lines in the body section of each
logical page.  When a line is not numbered, the current line number
is not incremented, but the line number separator character is still
prepended to the line.  The styles are:

@table @samp
@item a
number all lines,
@item t
number only nonempty lines (default for body),
@item n
do not number lines (default for header and footer),
@item p@var{regexp}
number only lines that contain a match for @var{regexp}.
@end table

@item -d @var{cd}
@itemx --section-delimiter=@var{cd}
@opindex -d
@opindex --section-delimiter
@cindex section delimiters of pages
Set the section delimiter characters to @var{cd}; default is
@samp{\:}. If only @var{c} is given, the second remains @samp{:}.
(Remember to protect @samp{\} or other metacharacters from shell
expansion with quotes or extra backslashes.)

@item -f @var{style}
@itemx --footer-numbering=@var{style}
@opindex -f
@opindex --footer-numbering
Analogous to @option{--body-numbering}.

@item -h @var{style}
@itemx --header-numbering=@var{style}
@opindex -h
@opindex --header-numbering
Analogous to @option{--body-numbering}.

@item -i @var{number}
@itemx --page-increment=@var{number}
@opindex -i
@opindex --page-increment
Increment line numbers by @var{number} (default 1).

@item -l @var{number}
@itemx --join-blank-lines=@var{number}
@opindex -l
@opindex --join-blank-lines
@cindex empty lines, numbering
@cindex blank lines, numbering
Consider @var{number} (default 1) consecutive empty lines to be one
logical line for numbering, and only number the last one.  Where fewer
than @var{number} consecutive empty lines occur, do not number them.
An empty line is one that contains no characters, not even spaces
or tabs.

@item -n @var{format}
@itemx --number-format=@var{format}
@opindex -n
@opindex --number-format
Select the line numbering format (default is @code{rn}):

@table @samp
@item ln
@opindex ln @r{format for @command{nl}}
left justified, no leading zeros;
@item rn
@opindex rn @r{format for @command{nl}}
right justified, no leading zeros;
@item rz
@opindex rz @r{format for @command{nl}}
right justified, leading zeros.
@end table

@item -p
@itemx --no-renumber
@opindex -p
@opindex --no-renumber
Do not reset the line number at the start of a logical page.

@item -s @var{string}
@itemx --number-separator=@var{string}
@opindex -s
@opindex --number-separator
Separate the line number from the text line in the output with
@var{string} (default is the TAB character).

@item -v @var{number}
@itemx --starting-line-number=@var{number}
@opindex -v
@opindex --starting-line-number
Set the initial line number on each logical page to @var{number} (default 1).

@item -w @var{number}
@itemx --number-width=@var{number}
@opindex -w
@opindex --number-width
Use @var{number} characters for line numbers (default 6).

@end table


@node od invocation
@section @command{od}: Write files in octal or other formats

@pindex od
@cindex octal dump of files
@cindex hex dump of files
@cindex ASCII dump of files
@cindex file contents, dumping unambiguously

@command{od} writes an unambiguous representation of each @var{file}
(@samp{-} means standard input), or standard input if none are given.
Synopses:

@example
od [@var{option}]@dots{} [@var{file}]@dots{}
od --traditional [@var{file}] [[+]@var{offset} [[+]@var{label}]]
@end example

Each line of output consists of the offset in the input, followed by
groups of data from the file. By default, @command{od} prints the offset in
octal, and each group of file data is two bytes of input printed as a
single octal number.

The program accepts the following options.  Also see @ref{Common options}.

@table @samp

@item -A @var{radix}
@itemx --address-radix=@var{radix}
@opindex -A
@opindex --address-radix
@cindex radix for file offsets
@cindex file offset radix
Select the base in which file offsets are printed.  @var{radix} can
be one of the following:

@table @samp
@item d
decimal;
@item o
octal;
@item x
hexadecimal;
@item n
none (do not print offsets).
@end table

The default is octal.

@item -j @var{bytes}
@itemx --skip-bytes=@var{bytes}
@opindex -j
@opindex --skip-bytes
Skip @var{bytes} input bytes before formatting and writing.  If
@var{bytes} begins with @samp{0x} or @samp{0X}, it is interpreted in
hexadecimal; otherwise, if it begins with @samp{0}, in octal; otherwise,
in decimal.  Appending @samp{b} multiplies @var{bytes} by 512, @samp{k}
by 1024, and @samp{m} by 1048576.

@item -N @var{bytes}
@itemx --read-bytes=@var{bytes}
@opindex -N
@opindex --read-bytes
Output at most @var{bytes} bytes of the input.  Prefixes and suffixes on
@code{bytes} are interpreted as for the @option{-j} option.

@item -s @var{n}
@itemx --strings[=@var{n}]
@opindex -s
@opindex --strings
@cindex string constants, outputting
Instead of the normal output, output only @dfn{string constants}: at
least @var{n} consecutive @acronym{ASCII} graphic characters,
followed by a null (zero) byte.

If @var{n} is omitted with @option{--strings}, the default is 3.  On
older systems, @sc{gnu} @command{od} instead supports an obsolete
option @option{-s[@var{n}]}, where @var{n} also defaults to 3.
@acronym{POSIX} 1003.1-2001 (@pxref{Standards conformance}) does not allow
@option{-s} without an argument; use @option{--strings} instead.

@item -t @var{type}
@itemx --format=@var{type}
@opindex -t
@opindex --format
Select the format in which to output the file data.  @var{type} is a
string of one or more of the below type indicator characters.  If you
include more than one type indicator character in a single @var{type}
string, or use this option more than once, @command{od} writes one copy
of each output line using each of the data types that you specified,
in the order that you specified.

Adding a trailing ``z'' to any type specification appends a display
of the @acronym{ASCII} character representation of the printable characters
to the output line generated by the type specification.

@table @samp
@item a
named character
@item c
@acronym{ASCII} character or backslash escape,
@item d
signed decimal
@item f
floating point
@item o
octal
@item u
unsigned decimal
@item x
hexadecimal
@end table

The type @code{a} outputs things like @samp{sp} for space, @samp{nl} for
newline, and @samp{nul} for a null (zero) byte.  Type @code{c} outputs
@samp{ }, @samp{\n}, and @code{\0}, respectively.

@cindex type size
Except for types @samp{a} and @samp{c}, you can specify the number
of bytes to use in interpreting each number in the given data type
by following the type indicator character with a decimal integer.
Alternately, you can specify the size of one of the C compiler's
built-in data types by following the type indicator character with
one of the following characters.  For integers (@samp{d}, @samp{o},
@samp{u}, @samp{x}):

@table @samp
@item C
char
@item S
short
@item I
int
@item L
long
@end table

For floating point (@code{f}):

@table @asis
@item F
float
@item D
double
@item L
long double
@end table

@item -v
@itemx --output-duplicates
@opindex -v
@opindex --output-duplicates
Output consecutive lines that are identical.  By default, when two or
more consecutive output lines would be identical, @command{od} outputs only
the first line, and puts just an asterisk on the following line to
indicate the elision.

@item -w @var{n}
@itemx --width[=@var{n}]
@opindex -w
@opindex --width
Dump @code{n} input bytes per output line.  This must be a multiple of
the least common multiple of the sizes associated with the specified
output types.

If this option is not given at all, the default is 16.  If @var{n} is
omitted with @option{--width}, the default is 32.  On older systems,
@sc{gnu} @command{od} instead supports an obsolete option
@option{-w[@var{n}]}, where @var{n} also defaults to 32.  @acronym{POSIX}
1003.1-2001 (@pxref{Standards conformance}) does not allow @option{-w}
without an argument; use @option{--width} instead.

@end table

The next several options are shorthands for format specifications.
@sc{gnu} @command{od} accepts any combination of shorthands and format
specification options.  These options accumulate.

@table @samp

@item -a
@opindex -a
Output as named characters.  Equivalent to @option{-ta}.

@item -b
@opindex -b
Output as octal bytes.  Equivalent to @option{-toC}.

@item -c
@opindex -c
Output as @acronym{ASCII} characters or backslash escapes.  Equivalent to
@option{-tc}.

@item -d
@opindex -d
Output as unsigned decimal shorts.  Equivalent to @option{-tu2}.

@item -f
@opindex -f
Output as floats.  Equivalent to @option{-tfF}.

@item -h
@opindex -h
Output as hexadecimal shorts.  Equivalent to @option{-tx2}.

@item -i
@opindex -i
Output as decimal shorts.  Equivalent to @option{-td2}.

@item -l
@opindex -l
Output as decimal longs.  Equivalent to @option{-td4}.

@item -o
@opindex -o
Output as octal shorts.  Equivalent to @option{-to2}.

@item -x
@opindex -x
Output as hexadecimal shorts.  Equivalent to @option{-tx2}.