File: coreutils.info,  Node: Backup options,  Next: Block size,  Up: Common options

2.1 Backup options
==================

Some GNU programs (at least ‘cp’, ‘install’, ‘ln’, and ‘mv’) optionally
make backups of files before writing new versions.  These options
control the details of these backups.  The options are also briefly
mentioned in the descriptions of the particular programs.

‘-b’
‘--backup[=METHOD]’
     Make a backup of each file that would otherwise be overwritten or
     removed.  Without this option, the original versions are destroyed.
     Use METHOD to determine the type of backups to make.  When this
     option is used but METHOD is not specified, then the value of the
     ‘VERSION_CONTROL’ environment variable is used.  And if
     ‘VERSION_CONTROL’ is not set, the default backup type is
     ‘existing’.

     Note that the short form of this option, ‘-b’ does not accept any
     argument.  Using ‘-b’ is equivalent to using ‘--backup=existing’.

     This option corresponds to the Emacs variable ‘version-control’;
     the values for METHOD are the same as those used in Emacs.  This
     option also accepts more descriptive names.  The valid METHODs are
     (unique abbreviations are accepted):

     ‘none’
     ‘off’
          Never make backups.

     ‘numbered’
     ‘t’
          Always make numbered backups.

     ‘existing’
     ‘nil’
          Make numbered backups of files that already have them, simple
          backups of the others.

     ‘simple’
     ‘never’
          Always make simple backups.  Please note ‘never’ is not to be
          confused with ‘none’.

‘-S SUFFIX’
‘--suffix=SUFFIX’
     Append SUFFIX to each backup file made with ‘-b’.  If this option
     is not specified, the value of the ‘SIMPLE_BACKUP_SUFFIX’
     environment variable is used.  And if ‘SIMPLE_BACKUP_SUFFIX’ is not
     set, the default is ‘~’, just as in Emacs.