If a file is downloaded more than once in the same directory, Wget's behavior depends on a few
options, including -nc. In certain cases, the local file will be clobbered, or overwritten, upon
repeated download. In other cases it will be preserved.
When running Wget without -N, -nc, -r, or -p, downloading the same file in the same directory will
result in the original copy of file being preserved and the second copy being named file.1. If that
file is downloaded yet again, the third copy will be named file.2, and so on. (This is also the
behavior with -nd, even if -r or -p are in effect.) When -nc is specified, this behavior is
suppressed, and Wget will refuse to download newer copies of file. Therefore, ""no-clobber"" is
actually a misnomer in this mode---it's not clobbering that's prevented (as the numeric suffixes were
already preventing clobbering), but rather the multiple version saving that's prevented.
When running Wget with -r or -p, but without -N, -nd, or -nc, re-downloading a file will result in
the new copy simply overwriting the old. Adding -nc will prevent this behavior, instead causing the
original version to be preserved and any newer copies on the server to be ignored.
When running Wget with -N, with or without -r or -p, the decision as to whether or not to download a
newer copy of a file depends on the local and remote timestamp and size of the file. -nc may not be
specified at the same time as -N.
Note that when -nc is specified, files with the suffixes .html or .htm will be loaded from the local
disk and parsed as if they had been retrieved from the Web.