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如何 grep cURL 的输出？

tag-icon • tag-icon bash command-line curl
如何 grep cURL 的输出？

我需要检索 SSL 证书的到期日期。该curl应用程序确实提供了以下信息：

$ curl -v https://google.com/
* Hostname was NOT found in DNS cache
*   Trying 212.179.180.121...
* Connected to google.com (212.179.180.121) port 443 (#0)
* successfully set certificate verify locations:
*   CAfile: none
  CApath: /etc/ssl/certs
* SSLv3, TLS handshake, Client hello (1):
* SSLv3, TLS handshake, Server hello (2):
* SSLv3, TLS handshake, CERT (11):
* SSLv3, TLS handshake, Server key exchange (12):
* SSLv3, TLS handshake, Server finished (14):
* SSLv3, TLS handshake, Client key exchange (16):
* SSLv3, TLS change cipher, Client hello (1):
* SSLv3, TLS handshake, Finished (20):
* SSLv3, TLS change cipher, Client hello (1):
* SSLv3, TLS handshake, Finished (20):
* SSL connection using ECDHE-ECDSA-AES128-GCM-SHA256
* Server certificate:
*        subject: C=US; ST=California; L=Mountain View; O=Google Inc; CN=*.google.com
*        start date: 2014-10-22 13:04:07 GMT
*        expire date: 2015-01-20 00:00:00 GMT
*        subjectAltName: google.com matched
*        issuer: C=US; O=Google Inc; CN=Google Internet Authority G2
*        SSL certificate verify ok.
> GET / HTTP/1.1
> User-Agent: curl/7.35.0
> Host: google.com
> Accept: */*
> 
< HTTP/1.1 302 Found
< Cache-Control: private
< Content-Type: text/html; charset=UTF-8
< Location: https://www.google.co.il/?gfe_rd=cr&ei=HkxbVMzCM-WkiAbU6YCoCg
< Content-Length: 262
< Date: Thu, 06 Nov 2014 10:23:26 GMT
* Server GFE/2.0 is not blacklisted
< Server: GFE/2.0
< 
<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
<TITLE>302 Moved</TITLE></HEAD><BODY>
<H1>302 Moved</H1>
The document has moved
<A HREF="https://www.google.co.il/?gfe_rd=cr&amp;ei=HkxbVMzCM-WkiAbU6YCoCg">here</A>.
</BODY></HTML>
* Connection #0 to host google.com left intact

然而，当通过结果管道输出时，grep不是较少的屏幕上的信息，而是多得多:

$ curl -v https://google.com/ | grep expire
* Hostname was NOT found in DNS cache
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0*   Trying 212.179.180.84...
* Connected to google.com (212.179.180.84) port 443 (#0)
* successfully set certificate verify locations:
*   CAfile: none
  CApath: /etc/ssl/certs
* SSLv3, TLS handshake, Client hello (1):
} [data not shown]
* SSLv3, TLS handshake, Server hello (2):
{ [data not shown]
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0* SSLv3, TLS handshake, CERT (11):
{ [data not shown]
* SSLv3, TLS handshake, Server key exchange (12):
{ [data not shown]
* SSLv3, TLS handshake, Server finished (14):
{ [data not shown]
* SSLv3, TLS handshake, Client key exchange (16):
} [data not shown]
* SSLv3, TLS change cipher, Client hello (1):
} [data not shown]
* SSLv3, TLS handshake, Finished (20):
} [data not shown]
* SSLv3, TLS change cipher, Client hello (1):
{ [data not shown]
* SSLv3, TLS handshake, Finished (20):
{ [data not shown]
* SSL connection using ECDHE-ECDSA-AES128-GCM-SHA256
* Server certificate:
*        subject: C=US; ST=California; L=Mountain View; O=Google Inc; CN=*.google.com
*        start date: 2014-10-22 13:04:07 GMT
*        expire date: 2015-01-20 00:00:00 GMT
*        subjectAltName: google.com matched
*        issuer: C=US; O=Google Inc; CN=Google Internet Authority G2
*        SSL certificate verify ok.
> GET / HTTP/1.1
> User-Agent: curl/7.35.0
> Host: google.com
> Accept: */*
> 
< HTTP/1.1 302 Found
< Cache-Control: private
< Content-Type: text/html; charset=UTF-8
< Location: https://www.google.co.il/?gfe_rd=cr&ei=IkxbVMy4K4OBbKuDgKgF
< Content-Length: 260
< Date: Thu, 06 Nov 2014 10:23:30 GMT
* Server GFE/2.0 is not blacklisted
< Server: GFE/2.0
< 
{ [data not shown]
100   260  100   260    0     0    714      0 --:--:-- --:--:-- --:--:--   714
* Connection #0 to host google.com left intact

我怀疑检测curl到它没有打印到终端，因此给出不同的输出，并非所有输出都被识别为grep存在stdout并因此传递到终端。然而，我能找到的最接近的东西man curl （永远不要用谷歌搜索！）这是：

PROGRESS METER
   curl  normally  displays  a  progress meter during operations, indicating the amount of transferred data, transfer speeds and estimated time
   left, etc.

   curl displays this data to the terminal by default, so if you invoke curl to do an operation and it is about to write data to the  terminal,
   it disables the progress meter as otherwise it would mess up the output mixing progress meter and response data.

   If you want a progress meter for HTTP POST or PUT requests, you need to redirect the response output to a file, using shell redirect (>), -o
   [file] or similar.

   It is not the same case for FTP upload as that operation does not spit out any response data to the terminal.

   If you prefer a progress "bar" instead of the regular meter, -# is your friend.

我怎样才能从输出expiry中得到这一行curl？此外，我应该读什么才能更好地了解情况？

看起来这将是一个很好的用例“stdmeta”文件描述符。

答案1

curl 将输出写入 stderr，因此重定向它并抑制进度：

curl -v --silent https://google.com/ 2>&1 | grep expire

curl将信息写入 stderr 的原因是这样您可以这样做：
curl <url> | someprgram没有该信息会破坏输入someprogram

答案2

可以用作--stderr -参数，将输出从 stderr（默认）重定向到 stdout。使用此选项，您还应该使用--silent来抑制进度条。

$ curl -v --silent https://google.com/ --stderr - | grep expire
*    expire date: 2015-09-01 00:00:00 GMT

答案3

这对我在 Ubuntu 和 Amazon Linux 2 上有效：

curl  --insecure -Ivv https://www.google.com/ 2>&1 | grep expire
  • 过期日期： 2021 年 12 月 4 日 01:14:00 GMT

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