Do not use the wget command without the mentioned arguments ! Otherwise, the downloaded file will be saved to disk. The wget command is used to save web content to disk.
If you remove the -O - it means that the downloaded content from the web will be saved to disk... but not to std-out (which is usually your LCD display - i.e. an open terminal with a Linux Shell interpreter). This is ensured by the -O - argument... so... that the downloaded content is "saved" to the standard output (on the monitor display - in layman's terms). Subsequently, at the end of the wget command-line, we will use redirection to the null-device, from this standard output (even in this case, of course, it is considered the standard output... and it means your LCD display - in layman's terms).
WGET man-page / download options: https://www.gnu.org/...ownload-Options
-O file
--output-document=file
The documents will not be written to the appropriate files, but all will be concatenated together and written to file. If ‘-’ is used as file, documents will be printed to standard output, disabling link conversion. (Use ‘./-’ to print to a file literally named ‘-’.)
Use of -O is not intended to mean simply “use the name file instead of the one in the URL;” rather, it is analogous to shell redirection: wget -O file http://foo is intended to work like wget -O - http://foo > file ; file will be truncated immediately, and all downloaded content will be written there.
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