coreutils: unexpand invocation

1 
1 9.3 ‘unexpand’: Convert spaces to tabs
1 ======================================
1 
1 ‘unexpand’ writes the contents of each given FILE, or standard input if
1 none are given or for a FILE of ‘-’, to standard output, converting
1 blanks at the beginning of each line into as many tab characters as
1 needed.  In the default POSIX locale, a “blank” is a space or a tab;
1 other locales may specify additional blank characters.  Synopsis:
1 
1      unexpand [OPTION]... [FILE]...
1 
1    By default, ‘unexpand’ converts only initial blanks (those that
1 precede all non-blank characters) on each line.  It preserves backspace
1 characters in the output; they decrement the column count for tab
1 calculations.  By default, tabs are set at every 8th column.
1 
11    The program accepts the following options.  Also see ⇒Common
 options.
1 
1 ‘-t TAB1[,TAB2]...’
1 ‘--tabs=TAB1[,TAB2]...’
1      If only one tab stop is given, set the tabs TAB1 columns apart
1      instead of the default 8.  Otherwise, set the tabs at columns TAB1,
1      TAB2, ... (numbered from 0), and leave blanks beyond the tab stops
1      given unchanged.  Tab stops can be separated by blanks as well as
1      by commas.
1 
1      As a GNU extension the last TAB specified can be prefixed with a
1      ‘/’ to indicate a tab size to use for remaining positions.  For
1      example, ‘--tabs=2,4,/8’ will set tab stops at position 2 and 4,
1      and every multiple of 8 after that.
1 
1      Also the last TAB specified can be prefixed with a ‘+’ to indicate
1      a tab size to use for remaining positions, offset from the final
1      explicitly specified tab stop.  For example, to ignore the 1
1      character gutter present in diff output, one can specify a 1
1      character offset using ‘--tabs=1,+8’, which will set tab stops at
1      positions 1,9,17,...
1 
1      This option implies the ‘-a’ option.
1 
1      For compatibility, GNU ‘unexpand’ supports the obsolete option
1      syntax, ‘-TAB1[,TAB2]...’, where tab stops must be separated by
1      commas.  (Unlike ‘-t’, this obsolete option does not imply ‘-a’.)
1      New scripts should use ‘--first-only -t TAB1[,TAB2]...’ instead.
1 
1 ‘-a’
1 ‘--all’
1      Also convert all sequences of two or more blanks just before a tab
1      stop, even if they occur after non-blank characters in a line.
1 
1    An exit status of zero indicates success, and a nonzero value
1 indicates failure.
1