expand, unexpand - Replaces tab characters with spaces or
spaces with tab characters
expand [-t tablist] [file...]
unexpand [-a | -t tablist] [file...]
Obsolescent syntax [Toc] [Back]
expand [-tabstop | -tab1,tab2,...,tabn] [file...]
Interfaces documented on this reference page conform to
industry standards as follows:
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Replaces spaces at the beginning of each line with a tab,
and inserts tab characters wherever their presence compresses
the resultant file by replacing two or more characters.
When the -t option is specified with the unexpand
command, the -a option has no effect. (This option
applies to the unexpand command only.) Specifies the tab
stops. The tablist argument consists of a single positive
decimal integer or multiple positive decimal integers,
separated by spaces or commas, in ascending order. If a
single number is specified, tabs are set tablist column
positions apart instead of the default (8). If multiple
numbers are specified, tabs are set at those specific column
positions. Tabbing to tab stop position n thus causes
the next character output to be in the (n+1)th column
position on that line.
If expand has 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 in the output. Sets tab stops tabstop
spaces apart instead of the default (8).
(Obsolescent) Sets tab stops at specified columns.
[Tru64 UNIX] Columns are measured in bytes.
The path name of a file to be processed. If you do not
specify this operand, standard input is read.
The expand command changes tab characters to spaces in the
named files, or the standard input, and writes the result
to the standard output.
The unexpand command puts tab characters into the data
from the standard input, or the named files, and writes
the result to the standard output.
Backspace characters are preserved in the output and
decrement the column count for tab calculations. The column
position count cannot be decremented below one. The
expand command is useful for preprocessing character files
(before sorting, looking at specific columns, and so on.)
that contain tab characters.
By default, unexpand converts only spaces that are within
sequences of spaces and tab characters at the beginnings
of lines. Use -a to convert other sequences of spaces.
If the expand command encounters difficulties opening any
specified file, it writes an error message to standard
error and terminates immediately with an error status.
If the unexpand command encounters difficulties opening
any specified file, it writes an error message to standard
error and continues operation. The exit status will
reflect the error.
The following exit values are returned by either command:
Successful completion. An error occurred.
To replace tab characters in file with spaces, enter:
expand file To replace the spaces in file with tab characters,
enter: unexpand -a file
ENVIRONMENT VARIABLES [Toc] [Back]
The following environment variables affect the execution
of expand and unexpand: Provides a default value for the
internationalization variables that are unset or null. If
LANG is unset or null, the corresponding value from the
default locale is used. If any of the internationalization
variables contain an invalid setting, the utility
behaves as if none of the variables had been defined. If
set to a non-empty string value, overrides the values of
all the other internationalization variables. Determines
the locale for the interpretation of sequences of bytes of
text data as characters (for example, single-byte as
opposed to multibyte characters in arguments). Determines
the locale for the format and contents of diagnostic messages
written to standard error. Determines the location
of message catalogues for the processing of LC_MESSAGES.
Commands: fold(1), tabs(1)
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