конвертировать табуляции в пробелы (convert tabs to spaces)
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
expand — convert tabs to spaces
Синопсис (Synopsis)
expand [-t tablist] [file...]
Описание (Description)
The expand utility shall write files or the standard input to the
standard output with <tab> characters replaced with one or more
<space> characters needed to pad to the next tab stop. Any
<backspace> characters shall be copied to the output and cause
the column position count for tab stop calculations to be
decremented; the column position count shall not be decremented
below zero.
Параметры (Options)
The expand utility shall conform to the Base Definitions volume
of POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
The following option shall be supported:
-t tablist
Specify the tab stops. The application shall ensure
that the argument tablist consists of either a single
positive decimal integer or a list of tabstops. If a
single number is given, tabs shall be set that number
of column positions apart instead of the default 8.
If a list of tabstops is given, the application shall
ensure that it consists of a list of two or more
positive decimal integers, separated by <blank> or
<comma> characters, in ascending order. The <tab>
characters shall be set at those specific column
positions. Each tab stop N shall be an integer value
greater than zero, and the list is in strictly
ascending order. This is taken to mean that, from the
start of a line of output, tabbing to position N shall
cause the next character output to be in the (N+1)th
column position on that line.
In the event of expand having to process a <tab> at a
position beyond the last of those specified in a
multiple tab-stop list, the <tab> shall be replaced by
a single <space> in the output.
Операнды (Operands)
The following operand shall be supported:
file The pathname of a text file to be used as input.
Стандартный ввод (Stdin)
See the INPUT FILES section.
Входные файлы (Input files)
Input files shall be text files.
Переменные окружения (Environment variables)
The following environment variables shall affect the execution of
expand:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base
Definitions volume of POSIX.1‐2017, Section 8.2,
Internationalization Variables for the precedence of
internationalization variables used to determine the
values of locale categories.)
LC_ALL If set to a non-empty string value, override the values
of all the other internationalization variables.
LC_CTYPE Determine the locale for the interpretation of
sequences of bytes of text data as characters (for
example, single-byte as opposed to multi-byte
characters in arguments and input files), the
processing of <tab> and <space> characters, and for the
determination of the width in column positions each
character would occupy on an output device.
LC_MESSAGES
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to
standard error.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
Асинхронные события (Asynchronous events)
Default.
Стандартный вывод (Stdout)
The standard output shall be equivalent to the input files with
<tab> characters converted into the appropriate number of <space>
characters.
Стандартный вывод сообщений (Stderr)
The standard error shall be used only for diagnostic messages.
Выходные файлы (Output files)
None.
Расширенное описание (Extended description)
None.
Статус выхода (Exit)
The following exit values shall be returned:
0 Successful completion
>0 An error occurred.
Последствия ошибок (Consequences of errors)
The expand utility shall terminate with an error message and non-
zero exit status upon encountering difficulties accessing one of
the file operands.
The following sections are informative.
Использование в приложениях (Application usage)
None.
Примеры (Examples)
None.
Обоснование (Rationale)
The expand utility is useful for preprocessing text files (before
sorting, looking at specific columns, and so on) that contain
<tab> characters.
See the Base Definitions volume of POSIX.1‐2017, Section 3.103,
Column Position.
The tablist option-argument consists of integers in ascending
order. Utility Syntax Guideline 8 mandates that expand shall
accept the integers (within the single argument) separated using
either <comma> or <blank> characters.
Earlier versions of this standard allowed the following form in
the SYNOPSIS:
expand [-tabstop][-tab1,tab2,...,tabn][file ...]
This form is no longer specified by POSIX.1‐2008 but may be
present in some implementations.
Будущие направления (Future directions)
None.
Смотри также (See also)
tabs(1p), unexpand(1p)
The Base Definitions volume of POSIX.1‐2017, Section 3.103,
Column Position, Chapter 8, Environment Variables, Section 12.2,
Utility Syntax Guidelines
