nghttp2/doc/bash_completion/nghttpx

_nghttpx()
{
    local cur prev split=false
    COMPREPLY=()
    COMP_WORDBREAKS=${COMP_WORDBREAKS//=}

    cmd=${COMP_WORDS[0]}
    _get_comp_words_by_ref cur prev
    case $cur in
        -*)
            COMPREPLY=( $( compgen -W '--backend --frontend --backlog --backend-address-family --backend-http-proxy-uri --workers --single-thread --read-rate --read-burst --write-rate --write-burst --worker-read-rate --worker-read-burst --worker-write-rate --worker-write-burst --worker-frontend-connections --backend-connections-per-host --backend-connections-per-frontend --rlimit-nofile --rlimit-memlock --backend-request-buffer --backend-response-buffer --fastopen --no-kqueue --frontend-http2-read-timeout --frontend-http3-read-timeout --frontend-read-timeout --frontend-write-timeout --frontend-keep-alive-timeout --stream-read-timeout --stream-write-timeout --backend-read-timeout --backend-write-timeout --backend-connect-timeout --backend-keep-alive-timeout --listener-disable-timeout --frontend-http2-setting-timeout --backend-http2-settings-timeout --backend-max-backoff --ciphers --tls13-ciphers --client-ciphers --tls13-client-ciphers --ecdh-curves --insecure --cacert --private-key-passwd-file --subcert --dh-param-file --npn-list --verify-client --verify-client-cacert --verify-client-tolerate-expired --client-private-key-file --client-cert-file --tls-min-proto-version --tls-max-proto-version --tls-ticket-key-file --tls-ticket-key-memcached --tls-ticket-key-memcached-address-family --tls-ticket-key-memcached-interval --tls-ticket-key-memcached-max-retry --tls-ticket-key-memcached-max-fail --tls-ticket-key-cipher --tls-ticket-key-memcached-cert-file --tls-ticket-key-memcached-private-key-file --fetch-ocsp-response-file --ocsp-update-interval --ocsp-startup --no-verify-ocsp --no-ocsp --tls-session-cache-memcached --tls-session-cache-memcached-address-family --tls-session-cache-memcached-cert-file --tls-session-cache-memcached-private-key-file --tls-dyn-rec-warmup-threshold --tls-dyn-rec-idle-timeout --no-http2-cipher-block-list --client-no-http2-cipher-block-list --tls-sct-dir --psk-secrets --client-psk-secrets --tls-no-postpone-early-data --tls-max-early-data --tls-ktls --frontend-http2-max-concurrent-streams --backend-http2-max-concurrent-streams --frontend-http2-window-size --frontend-http2-connection-window-size --backend-http2-window-size --backend-http2-connection-window-size --http2-no-cookie-crumbling --padding --no-server-push --frontend-http2-optimize-write-buffer-size --frontend-http2-optimize-window-size --frontend-http2-encoder-dynamic-table-size --frontend-http2-decoder-dynamic-table-size --backend-http2-encoder-dynamic-table-size --backend-http2-decoder-dynamic-table-size --http2-proxy --log-level --accesslog-file --accesslog-syslog --accesslog-format --accesslog-write-early --errorlog-file --errorlog-syslog --syslog-facility --add-x-forwarded-for --strip-incoming-x-forwarded-for --no-add-x-forwarded-proto --no-strip-incoming-x-forwarded-proto --add-forwarded --strip-incoming-forwarded --forwarded-by --forwarded-for --no-via --no-strip-incoming-early-data --no-location-rewrite --host-rewrite --altsvc --http2-altsvc --add-request-header --add-response-header --request-header-field-buffer --max-request-header-fields --response-header-field-buffer --max-response-header-fields --error-page --server-name --no-server-rewrite --redirect-https-port --require-http-scheme --api-max-request-body --dns-cache-timeout --dns-lookup-timeout --dns-max-try --frontend-max-requests --frontend-http2-dump-request-header --frontend-http2-dump-response-header --frontend-frame-debug --daemon --pid-file --user --single-process --max-worker-processes --worker-process-grace-shutdown-period --mruby-file --ignore-per-pattern-mruby-error --frontend-quic-idle-timeout --frontend-quic-debug-log --quic-bpf-program-file --frontend-quic-early-data --frontend-quic-qlog-dir --frontend-quic-require-token --frontend-quic-congestion-controller --frontend-quic-secret-file --quic-server-id --frontend-quic-initial-rtt --no-quic-bpf --frontend-http3-window-size --frontend-http3-connection-window-size --frontend-http3-max-window-size --frontend-http3-max-connection-window-size --frontend-http3-max-concurrent-streams --conf --include --version --help ' -- 
            ;;
        *)
            _filedir
            return 0
    esac
    return 0
}
complete -F _nghttpx nghttpx