What does “wget -O” mean?

问题

I have an wget command like this in my shell script:

reponse="`wget -O- http:localhost:8080/app/index.html`"

I don't understand the -O- option. I was explained that -O is output to somewhere and - is output to the current stream. I don't see any explaination of "-" in wget. Is that a standard thing for shell scripting. Where I can find reference to it?

Thanks,

回答1:

Here's the man page of wget -O:

http://www.gnu.org/software/wget/manual/html_node/Download-Options.html#Download-Options

Here's a few examples:

wget with no flag
```
wget www.stackoverflow.com
```
Output:

A file named as index.html
wget with -O flag
```
wget -O filename.html www.stackoverflow.com
```
Output:

A file named as filename.html
wget with -O- flag
```
wget -O- www.stackoverflow.com
```
Output:

Output to stdout

回答2:

for the manual of wget: use man wget if you are on Unix platform. Else, try "man page wget" on google.

The -O- stand for "Get as a file and print the result on STDOUT"

回答3:

Depending on your system you should be able to find reference by typing man wget. The GNU Wget man page says this of the -O|--output-document flag:

If - is used as file, documents will be printed to standard output, disabling link conversion. (Use ./- to print to a file literally named -.)

And continues…

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.

It's not uncommon to see combined with -q and written as -q0- or -q0 - followed by a uri. It validates against the POSIX standard so, yeah, I'd say it's a standard thing for shell scripting.

来源：https://stackoverflow.com/questions/9830242/what-does-wget-o-mean

标签

wget