如何使用 shell 脚本确定网页是否存在? [英] How do I determine if a web page exists with shell scripting?
问题描述
我正在尝试制作一个程序,可以将一系列漫画扫描文件转换为一个 pdf 文件,我不想尝试下载图片来确定我是否有正确的 url.是否有可用于检查网页是否存在的 shell 脚本命令?
I am trying to make a program that can convert a series of manga scans into one pdf file, and I don't want to have to attempt to download the picture to determine if I have the right url. Is there a shell scripting command that I can use to just check if a web page exists?
推荐答案
在 *NIX 下,您可以使用 curl
发出一个简单的 HEAD
请求(HEAD
只要求标题,而不是页面正文):
Under a *NIX, you can use curl
to issue a simple HEAD
request (HEAD
only asks for the headers, not the page body):
curl --head http://myurl/
那么你可以只取第一行,其中包含 HTTP 状态代码(200 OK、404 Not Found 等):
Then you can take only the first line, which contains the HTTP status code (200 OK, 404 Not Found, etc.):
curl -s --head http://myurl/ | head -n 1
然后检查您是否得到了不错的回复(状态代码是 200 或 3**):
And then check if you got a decent response (status code is 200 or 3**):
curl -s --head http://myurl/ | head -n 1 | grep "HTTP/1.[01] [23].."
如果状态代码正常,这将输出第一行,否则将不输出任何内容.您也可以将其通过管道传输到/dev/null 以获取不输出,并使用 $?
来确定它是否有效:
This will output the first line if the status code is okay, or nothing if it isn't. You can also pipe that to /dev/null to get no output, and use $?
to determine if it worked or no:
curl -s --head http://myurl/ | head -n 1 | grep "HTTP/1.[01] [23].." > /dev/null
# on success (page exists), $? will be 0; on failure (page does not exist or
# is unreachable), $? will be 1
EDIT -s
只是告诉 curl
不要显示进度条".
EDIT -s
simply tells curl
to not show a "progress bar".
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