NAME
expand - convert tabs to spaces
SYNOPSIS
expand [-t tablist][file ...]
DESCRIPTION
The expand utility shall write files or the standard input to the
standard output with <tab>s replaced with one or more <space>s needed
to pad to the next tab stop. Any <backspace>s 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.
OPTIONS
The expand utility shall conform to the Base Definitions volume of
IEEE Std 1003.1-2001, 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>s or commas, in ascending order. The tabs 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.
OPERANDS
The following operand shall be supported:
file The pathname of a text file to be used as input.
STDIN
See the INPUT FILES section.
INPUT FILES
Input files shall be text files.
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
IEEE Std 1003.1-2001, 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>s and <space>s, 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 .
ASYNCHRONOUS EVENTS
Default.
STDOUT
The standard output shall be equivalent to the input files with <tab>s
converted into the appropriate number of <space>s.
STDERR
The standard error shall be used only for diagnostic messages.
OUTPUT FILES
None.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
0 Successful completion
>0 An error occurred.
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.
APPLICATION USAGE
None.
EXAMPLES
None.
RATIONALE
The expand utility is useful for preprocessing text files (before
sorting, looking at specific columns, and so on) that contain <tab>s.
See the Base Definitions volume of IEEE Std 1003.1-2001, 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 commas or
<blank>s.
FUTURE DIRECTIONS
None.
SEE ALSO
tabs , unexpand
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.opengroup.org/unix/online.html .