Non-working output to stdou?

Good afternoon, for the second time faced with this conclusion.
How it is done and why it is impossible to work
nginx -V | grep I
stdou
nginx -V | grep aaadfa
nginx version: nginx/1.14.0 (Ubuntu)
built with OpenSSL 1.1.0 g 2 Nov 2017 (running with OpenSSL 1.1.1 b 26 Feb 2019)
TLS SNI support enabled
configure arguments: --with-cc-opt='-g -O2 -fdebug-prefix-map=/build/nginx-FIJPpj/nginx-1.14.0=. -fstack-protector-strong -Wformat -Werror=format-security-fPIC -Wdate-time-D_FORTIFY_SOURCE=2' --with-ld-opt='-Wl,-Bsymbolic-functions -Wl,-z,relro -Wl,-z,now-fPIC' --prefix=/usr/share/nginx --conf-path=/etc/nginx/nginx.conf --http-log-path=/var/log/nginx/access.log --error-log-path=/var/log/nginx/error.log --lock-path=/var/lock/nginx.lock --pid-path=/run/nginx.pid --modules-path=/usr/lib/nginx/modules --http-client-body-temp-path=/var/lib/nginx/body --http-fastcgi-temp-path=/var/lib/nginx/fastcgi --http-proxy-temp-path=/var/lib/nginx/proxy --http-scgi-temp-path=/var/lib/nginx/scgi --http-uwsgi-temp-path=/var/lib/nginx/uwsgi --with-debug --with-pcre-jit --with-http_ssl_module --with-http_stub_status_module --with-http_realip_module --with-http_auth_request_module --with-http_v2_module --with-http_dav_module --with-http_slice_module --with-threads --with-http_addition_module --with-http_geoip_mod

In the beginning thought it was such a line, but neither sed nor anything else the string does not parse, it seems like it is but it is not.
Where does the output and how to catch him?
March 19th 20 at 08:48
1 answer
March 19th 20 at 08:50
Solution
Goes to stderr, so to send it in grep do this:
nginx -V 2>&1 | grep ...
had that idea but dismissed as stupid, however ;) - osbaldo46 commented on March 19th 20 at 08:53
@osbaldo46, A utility certificate is printed to stderr. - selena_Nienow commented on March 19th 20 at 08:56

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