Get nginx version synchronously?

问题:

Something weird is going on when I try to get the nginx version.

When I run this command:

echo "[nginx]" $(nginx -v)

It prints

nginx version: nginx/1.4.6 (Ubuntu)
[nginx]

Notice the [nginx] bit is below the nginx version.

When I try with Node OTOH, echo "[node]" $(node --version), I get:

[node] v0.10.45

Which is in the expected order, so it's not a problem with echo. How can I get nginx to print in the proper order?

Not sure if this is a Bash/shell issue or something funny with the nginx program or what.

回答1:

Who knows why the decision was made, but nginx outputs to stderr. You can capture it by piping stderr to stdout:

echo "[nginx]" $(nginx -v 2>&1)

回答2:

If you wanted to pipe it to a format string you could do:

$(nginx -v) | printf "[nginx] "

or even...

nginx -v | printf "[nginx]%1s"