EXPAND(1P) POSIX Programmer's Manual EXPAND(1P)
PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the correspond-
ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
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> 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.
OPTIONS
The expand utility shall conform to the Base Definitions volume of POSIX.1-2008, 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 inte-
ger 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 posi-
tions. 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
POSIX.1-2008, 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.
ASYNCHRONOUS EVENTS
Default.
STDOUT
The standard output shall be equivalent to the input files with <tab> characters converted into the appropriate number of <space> charac-
ters.
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> char-
acters.
See the Base Definitions volume of POSIX.1-2008, 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 inte-
gers (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.
FUTURE DIRECTIONS
None.
SEE ALSO
tabs, unexpand
The Base Definitions volume of POSIX.1-2008, Section 3.103, Column Position, Chapter 8, Environment Variables, Section 12.2, Utility Syntax
Guidelines
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition, Standard for Information Technol-
ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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 Stan-
dard is the referee document. The original Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source
files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE
/The Open Group 2013 EXPAND(1P)