expand - convert tabs to spaces
expand [ -t tablist ] [ file ]
The expand utility writes 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 will be
copied to the output and cause the column position count for tab stop
calculations to be decremented; the column position count will not be
decremented below zero.
expand may be used with the following options:
Specify the tab stops. The argument tablist must consist of a single
positive decimal integer or multiple positive decimal integers,
separated by blank characters or commas, in ascending order. If a
single number is given, tabs will be set tablist column positions
apart instead of the default 8. If multiple numbers are given, the
tabs will be set at those specific column positions.
Each tab-stop position N must be an integer value greater than zero,
and the list must be in strictly ascending order. This is taken to
mean that, from the start of a line of output, tabbing to position N
causes the next character be in the (N+1)th column position on that
In the event of expand having to process a tab character at a
position beyond the last of those specified in a multiple tab-stop
list, the tab character is replaced by a single space character in
The following operand is supported:
-t file The pathname of a text file to be used as input.
See INPUT FILES.
Input files must be text files.
ENVIRONMENT VARIABLES [Toc] [Back]
The following environment variables affect the execution of expand:
LANG Provide a default value for the internationalisation variables
that are unset or null. If LANG is unset or null, the corresponding value
from the implementation-specific default locale will be used. If any of
the internationalisation variables contains an invalid setting, the
utility will behave as if none of the variables had been defined.
LC_ALL If set to a non-empty string value, override the values of
all the other internationalisation variables.
LC_CTYPE Determine the locale for the interpretation of sequences of
bytes of text data as characters (for example, single- 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 a constant-width font
LC_MESSAGES Determine the locale that should be used to affect the
format and contents of diagnostic messages written to standard error.
The standard output is equivalent to the input files with tab characters
converted into the appropriate number of space characters.
Used only for diagnostic messages.
The following exit values are returned:
0 Successful completion.
>0 An error occurred.
CONSEQUENCES OF ERRORS
The expand utility will terminate with an error message and non-zero exit
status upon encountering difficulties accessing one of the file operands.
First released in Issue 4.
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