普段何気なく使っているcurlですが 便利なオプション(-w, –write-out)が意外と知られていないと思いましたので、紹介したいと思います。
curlの便利なオプション(-w,–write-out)について
curl –helpコマンドを実行してみると下記のようにFORMATを利用した出力であることが記載されています。詳細は、curl –manualで確認できます。
〜省略〜
-w, --write-out <format> Use output FORMAT after completion
--xattr Store metadata in extended file attributes
curl –manualの出力結果
-w, --write-out <format>
Make curl display information on stdout after a completed trans-
fer. The format is a string that may contain plain text mixed
with any number of variables. The format can be specified as a
literal "string", or you can have curl read the format from a
file with "@filename" and to tell curl to read the format from
stdin you write "@-".
The variables present in the output format will be substituted
by the value or text that curl thinks fit, as described below.
All variables are specified as %{variable_name} and to output a
normal % you just write them as %%. You can output a newline by
using \n, a carriage return with \r and a tab space with \t.
The output will be written to standard output, but this can be
switched to standard error by using %{stderr}.
NOTE: The %-symbol is a special symbol in the win32-environment,
where all occurrences of % must be doubled when using this op-
tion.
The variables available are:
content_type The Content-Type of the requested document, if
there was any.
filename_effective
The ultimate filename that curl writes out to.
This is only meaningful if curl is told to write
to a file with the -O, --remote-name or -o,
--output option. It's most useful in combination
with the -J, --remote-header-name option. (Added
in 7.26.0)
ftp_entry_path The initial path curl ended up in when logging on
to the remote FTP server. (Added in 7.15.4)
http_code The numerical response code that was found in the
last retrieved HTTP(S) or FTP(s) transfer. In
7.18.2 the alias response_code was added to show
the same info.
http_connect The numerical code that was found in the last re-
sponse (from a proxy) to a curl CONNECT request.
(Added in 7.12.4)
http_version The http version that was effectively used.
(Added in 7.50.0)
local_ip The IP address of the local end of the most re-
cently done connection - can be either IPv4 or
IPv6 (Added in 7.29.0)
local_port The local port number of the most recently done
connection (Added in 7.29.0)
num_connects Number of new connects made in the recent trans-
fer. (Added in 7.12.3)
num_redirects Number of redirects that were followed in the re-
quest. (Added in 7.12.3)
proxy_ssl_verify_result
The result of the HTTPS proxy's SSL peer certifi-
cate verification that was requested. 0 means the
verification was successful. (Added in 7.52.0)
redirect_url When an HTTP request was made without -L, --loca-
tion to follow redirects (or when --max-redir is
met), this variable will show the actual URL a
redirect would have gone to. (Added in 7.18.2)
remote_ip The remote IP address of the most recently done
connection - can be either IPv4 or IPv6 (Added in
7.29.0)
remote_port The remote port number of the most recently done
connection (Added in 7.29.0)
scheme The URL scheme (sometimes called protocol) that
was effectively used (Added in 7.52.0)
size_download The total amount of bytes that were downloaded.
size_header The total amount of bytes of the downloaded head-
ers.
size_request The total amount of bytes that were sent in the
HTTP request.
size_upload The total amount of bytes that were uploaded.
speed_download The average download speed that curl measured for
the complete download. Bytes per second.
speed_upload The average upload speed that curl measured for
the complete upload. Bytes per second.
ssl_verify_result
The result of the SSL peer certificate verifica-
tion that was requested. 0 means the verification
was successful. (Added in 7.19.0)
stderr From this point on, the -w, --write-out output
will be written to standard error. (Added in
7.63.0)
stdout From this point on, the -w, --write-out output
will be written to standard output. This is the
default, but can be used to switch back after
switching to stderr. (Added in 7.63.0)
time_appconnect
The time, in seconds, it took from the start un-
til the SSL/SSH/etc connect/handshake to the re-
mote host was completed. (Added in 7.19.0)
time_connect The time, in seconds, it took from the start un-
til the TCP connect to the remote host (or proxy)
was completed.
time_namelookup
The time, in seconds, it took from the start un-
til the name resolving was completed.
time_pretransfer
The time, in seconds, it took from the start un-
til the file transfer was just about to begin.
This includes all pre-transfer commands and nego-
tiations that are specific to the particular pro-
tocol(s) involved.
time_redirect The time, in seconds, it took for all redirection
steps including name lookup, connect, pretransfer
and transfer before the final transaction was
started. time_redirect shows the complete execu-
tion time for multiple redirections. (Added in
7.12.3)
time_starttransfer
The time, in seconds, it took from the start un-
til the first byte was just about to be trans-
ferred. This includes time_pretransfer and also
the time the server needed to calculate the re-
sult.
time_total The total time, in seconds, that the full opera-
tion lasted.
url_effective The URL that was fetched last. This is most mean-
ingful if you've told curl to follow location:
headers.
利用してみる
出力フォーマットを指定したファイル(curl_env.txt)を作成します。
url_effective\t\t: %{url_effective}\n
http_code\t\t: %{http_code}\n
http_connect\t\t: %{http_connect}\n
time_total\t\t: %{time_total}\n
time_namelookup\t\t: %{time_namelookup}\n
time_connect\t\t: %{time_connect}\n
time_appconnect\t\t: %{time_appconnect}\n
time_pretransfer\t\t: %{time_pretransfer}\n
time_redirect\t\t: %{time_redirect}\n
time_starttransfer\t\t: %{time_starttransfer}\n
size_download\t\t: %{size_download}\n
size_upload\t\t: %{size_upload}\n
size_header\t\t: %{size_header}\n
size_request\t\t: %{size_request}\n
speed_download\t\t: %{speed_download}\n
speed_upload\t\t: %{speed_upload}フォーマットファイルは、下記のように指定します。
curl -o /dev/null https://targetsite.com -w @curl_env.txt -s 実行結果です。この例では、time_namelookupに時間がかかっているのでDNSの名前解決で時間がかかっているということがわかります。
url_effective : http://xxxxx
http_code : 200
http_connect : 000
time_total : 5.130927
time_namelookup : 5.096498
time_connect : 5.096648
time_appconnect : 0.000000
time_pretransfer : 5.096674
time_redirect : 0.000000
time_starttransfer : 5.130713
size_download : 12978
size_upload : 0
size_header : 314
size_request : 88
speed_download : 2529.000
speed_upload : 0.000⏎今回は、curlのwオプションを利用したボトルネック調査について記載しました。お疲れ様でした。
