[英]How to extract first n characters of a string in varnish-vcl?
I'm looking for a way to extract the first 'n' characters from a string in VCL. 我正在寻找一种从VCL中的字符串中提取第一个“ n”个字符的方法。 I couldn't find any function like trim(str,starting_pos) or substring(str,len) in the VCL documentation. 我在VCL文档中找不到任何诸如trim(str,starting_pos)或substring(str,len)的函数。 I've tried searching for this on google and stackoverflow and nothing came up, so I'm asking here. 我尝试在Google和stackoverflow上搜索此内容,但没有任何反应,所以我在这里问。 I appreciate your help. 我感谢您的帮助。
I'm not aware of any such string functions being available in the Fastly Varnish environment. 我不知道在Fastly Varnish环境中可以使用任何此类字符串函数。
However, I think you could accomplish the same using regular expression capture groups. 但是,我认为您可以使用正则表达式捕获组来完成相同的操作。
set req.http.Foo = "foobar";
if (req.http.Foo ~ "^(.{0,3})") {
set resp.http.match0 = re.group.0; # this should now equal 'foo'
}
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