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如何grep cURL的輸出？
我需要檢索 SSL 證書的到期日期。該
curl應用程序確實提供了以下資訊：$ 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&ei=HkxbVMzCM-WkiAbU6YCoCg">here</A>. </BODY></HTML> * Connection #0 to host google.com left intact然而，當通過
grep結果管道輸出時，螢幕上的資訊不是更少，而是更多：$ 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我懷疑檢測
curl到它沒有列印到終端，因此給出了不同的輸出，並不是所有的輸出都被辨識grep為存在stdout並因此傳遞到終端。然而，我能找到的最接近這個的東西man curl**（永遠不要用Google搜尋！）**是這樣的：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.**我怎樣才能
expiry從輸出中得到這條線curl？**此外，我應該閱讀什麼以更好地了解情況？似乎這對於“stdmeta”文件描述符來說是一個很好的案例。
curl 將輸出寫入 stderr，因此重定向它並抑制進度：
curl -v --silent https://google.com/ 2>&1 | grep expire
curl將資訊寫入 stderr的原因是您可以這樣做：
curl <url> | someprgram沒有該資訊破壞someprogram
可以
--stderr -用作參數，將輸出從 stderr（預設）重定向到 stdout。使用此選項，您還應該使用--silent來抑制進度條。$ curl -v --silent https://google.com/ --stderr - | grep expire * expire date: 2015-09-01 00:00:00 GMT