неинтерактивный сетевой загрузчик (The non-interactive network downloader.)
Статус выхода (Exit)
Wget may return one of several error codes if it encounters
problems.
0 No problems occurred.
1 Generic error code.
2 Parse error---for instance, when parsing command-line
options, the .wgetrc or .netrc...
3 File I/O error.
4 Network failure.
5 SSL verification failure.
6 Username/password authentication failure.
7 Protocol errors.
8 Server issued an error response.
With the exceptions of 0 and 1, the lower-numbered exit codes
take precedence over higher-numbered ones, when multiple types of
errors are encountered.
In versions of Wget prior to 1.12, Wget's exit status tended to
be unhelpful and inconsistent. Recursive downloads would
virtually always return 0 (success), regardless of any issues
encountered, and non-recursive fetches only returned the status
corresponding to the most recently-attempted download.
