Certain options are available in all these programs. Rather than writing identical descriptions for each of the programs, they are described here. (In fact, every GNU program accepts (or should accept) these options.)
Some GNU programs (at least
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.
SIMPLE_BACKUP_SUFFIXenvironment variable is used. And if
SIMPLE_BACKUP_SUFFIXis not set, the default is `~', just as in Emacs.
VERSION_CONTROLenvironment variable is used. And if
VERSION_CONTROLis not set, the default backup type is `existing'. This option corresponds to the Emacs variable `version-control'; the same values for method are accepted as in Emacs. This options also more descriptive name. The valid methods (unique abbreviations are accepted):