coreutils: Backup options

1 
1 2.2 Backup options
1 ==================
1 
1 Some GNU programs (at least ‘cp’, ‘install’, ‘ln’, and ‘mv’) optionally
1 make backups of files before writing new versions.  These options
1 control the details of these backups.  The options are also briefly
1 mentioned in the descriptions of the particular programs.
1 
1 ‘-b’
1 ‘--backup[=METHOD]’
1      Make a backup of each file that would otherwise be overwritten or
1      removed.  Without this option, the original versions are destroyed.
1      Use METHOD to determine the type of backups to make.  When this
1      option is used but METHOD is not specified, then the value of the
1      ‘VERSION_CONTROL’ environment variable is used.  And if
1      ‘VERSION_CONTROL’ is not set, the default backup type is
1      ‘existing’.
1 
1      Note that the short form of this option, ‘-b’ does not accept any
1      argument.  Using ‘-b’ is equivalent to using ‘--backup=existing’.
1 
1      This option corresponds to the Emacs variable ‘version-control’;
1      the values for METHOD are the same as those used in Emacs.  This
1      option also accepts more descriptive names.  The valid METHODs are
1      (unique abbreviations are accepted):
1 
1      ‘none’
1      ‘off’
1           Never make backups.
1 
1      ‘numbered’
1      ‘t’
1           Always make numbered backups.
1 
1      ‘existing’
1      ‘nil’
1           Make numbered backups of files that already have them, simple
1           backups of the others.
1 
1      ‘simple’
1      ‘never’
1           Always make simple backups.  Please note ‘never’ is not to be
1           confused with ‘none’.
1 
1 ‘-S SUFFIX’
1 ‘--suffix=SUFFIX’
1      Append SUFFIX to each backup file made with ‘-b’.  If this option
1      is not specified, the value of the ‘SIMPLE_BACKUP_SUFFIX’
1      environment variable is used.  And if ‘SIMPLE_BACKUP_SUFFIX’ is not
1      set, the default is ‘~’, just as in Emacs.
1