NAME
expand, unexpand — expand tabs to spaces, and vice versa
SYNOPSIS
expand
[-t
tablist]
[file ...]
unexpand
[-a]
[-t
tablist]
[file ...]
Obsolescent:
expand
[-
tabstop]
[-
tab1,tab2,
...,
tabn]
[file ...]
DESCRIPTION
expand
processes the named files or the standard input
and writes to the standard output with tabs changed into spaces.
Backspace characters are preserved in the output,
and the column count is decreased by one column for tab calculations.
For proper tab calculation, if a multi-column character is to be
"backspace'd", it should be followed by multiple backspace
characters which equal to it's column width.
If a tab character is found after the last tab position,
it is replaced by a single space.
expand
is useful for preprocessing character files
that contain tabs (before sorting, looking at specific columns, etc).
expand
recognizes the following command-line options and arguments:
- [-t tablist]
tablist
specifies where to set the tab positions instead of the default
8.
tablist
can take two forms.
If it is a single number, tabs are set
tablist
spaces apart.
tablist
can also be a blank- or comma-separated list
of increasing positions where tabs are to be set.
- [-tabstop]
This option is obsolescent and is equivalent to using
-t tabstop.
- [-tab1,tab2,...,tabn]
This option is obsolescent and is equivalent to using
-t
tab1,tab2, ...
,tabn.
unexpand
processes the named files or the standard input
and writes to the standard output
with spaces changed into tabs where possible.
By default, only leading spaces and tabs
are converted to maximal strings of tabs.
The default tab position is every 8 characters.
Backspace characters are preserved into the output,
and the column count is decreased by one column for tab calculations.
For proper tab calculation, if a multi-column character is to be
"backspace'd", it should be followed by multiple backspace
characters which equal to it's column width.
unexpand
recognizes the following command-line options and arguments:
- -a
Tabs are inserted whenever they would compress the resultant file
by replacing two or more spaces before a tab position.
- -t tablist
tablist
specifies the tab positions.
tablist
can take two forms.
If it is a single number, tabs are set every
tablist
spaces apart.
If
tablist
is a blank- or comma-separated list of increasing positions,
tabs are set at those locations.
The
-t
option implies the
-a
option.
If the
-t
option is not specified, the default is equivalent to specifying
-t 8
except that
-a
is not implied for this case.
EXTERNAL INFLUENCES
Environment Variables
LC_CTYPE
determines the interpretation of text as single and/or
multi-byte characters.
LC_MESSAGES
determines the language in which messages are displayed.
If
LC_CTYPE
or
LC_MESSAGES
is not specified in the environment or is set to
the empty string, the value of
LANG
is used as a default for each
unspecified or empty variable.
If
LANG
is not specified or is set to the empty string, a default of "C" (see
lang(5))
is used instead of
LANG.
If any internationalization variable contains an invalid setting,
expand
and
unexpand
behave as if all internationalization variables are set to "C".
See
environ(5).
If
LC_ALL
is set to a non-empty string value, it overrides the values
of all the other internationalization variables.
International Code Set Support
Single- and multi-byte character code sets are supported
with the exception that
unexpand
do not recognize multi-byte alternative space characters.
STANDARDS CONFORMANCE
expand: XPG4, POSIX.2
unexpand: XPG4, POSIX.2
Printable version
