给定以下 shell 脚本,请问有人能解释一下 grep -Po
正则表达式吗?
#!/bin/bash
# Issue the request for a bearer token, json is returned
raw_json=`curl -s -X POST -d "username=name&password=secret&client_id=security-admin-console" http://localhost:8081/auth/realms/master/tokens/grants/access`
# Strip away all but the "access_token" field's value using a Python regular expression
bearerToken=`echo $raw_json | grep -Po '"'"access_token"'"\s*:\s*"\K([^"]*)'`
echo "The bearer token is:"
echo $bearerToken
具体来说,我有兴趣了解正则表达式的各个部分
grep -Po '"'"access_token"'"\s*:\s*"\K([^"]*)'`
及其运作方式。为什么引用那么多? “克”是干什么用的?我对 grep regex 有一些经验,但这让我很困惑。
这是 curl 命令的实际输出,shell 脚本 (grep) 按预期工作,仅返回“access_token”值的内容。
{"access_token":"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.fQmQKn-xatvflHPAaxCfrrVow3ynpw0sREho7__jZo2d0g1SwZV7Lf4C26CcweNLlb3wmKHHo63HRz35qRxJ7BXyiZwHgXokvDJj13yuOb6Sirg9z02n6fwGy8Iog30pUvffnDaVnUWHfVL-h_R4-OZNf-_YUK5RcL2DHt0zUXI","expires_in":60,"refresh_expires_in":1800,"refresh_token":"eyJhbGciOiJSUzI1NiJ9.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.WeiJOC1jQ52aKgnW8UN2Lv9rJ_yKZiOhijOYKLN2EEOkYF8rvRZsSKbTPFKTIUvjnwy2A7V_N-GhhJH4C-T7F5__QPNofSXbCNyvATj52jGLxk9V0Afvk-Z5QAWi55PJRTC0qteeMRcO2Frw-0KtKYe9o3UcGICJubxhZHsXBLA","token_type":"bearer","id_token":"eyJhbGciOiJSUzI1NiJ9.eyJuYW1lIjoiIiwianRpIjoiMGIyMGI0ODctOTI4OS00YTFhLTgyNmMtM2NiOTg0MDJkMzVkIiwiZXhwIjoxNDQ2ODI4MDU5LCJuYmYiOjAsImlhdCI6MTQ0NjgyNzk5OIwouldhaveToBeNutsUiLCJwcmVmZXJyZWRfdXNlcm5hbWUiOiJhZG1pbiIsImVtYWlsX3ZlcmlmaWVkIjpmYWxzZX0.DmG8Lm4niL1djzNrLsZ2CrsB1ZzUPnR2Nm7IZnrwrmkXsrPxjl6pyXKCWSj6pbk2sgVI8NNFqrGIJmEJ7gkTZWm328VGGpJsmMuJBki0KbqBRKORGQSgkas_34rwzhcTE3Iki8h_YVs2vvNIx_eZSOvIzyEcP3IGHuBoxcR6W3E","not-before-policy":0,"session-state":"62efc05c-1bf5-4f55-b749-5e0eff94155b"}
万一有人找到这篇文章,这就是我最终使用的:
if hash jq 2>/dev/null; then
# Use the jq command to safely parse json
bearerToken=$(echo $raw_json | jq -r '.access_token')
else
# Strip away all but the "access_token" field's value using a perl regular expression
bearerToken=$(echo $raw_json | grep -Po '"'"access_token"'"\s*:\s*"\K([^"]*)')
fi
最佳答案
因为不是所有的正则表达式风格都支持 lookbehind,Perl 引入了 \K
。一般来说,当你有:
a\Kb
当匹配“b”时,\K
告诉引擎假装匹配尝试从这个位置开始。
在您的示例中,您想要假装匹配尝试从出现在 "access_token":"
文本之后的内容开始。
此示例将更好地演示 \K
用法:
~$ echo 'hello world' | grep -oP 'hello \K(world)'
world
~$ echo 'hello world' | grep -oP 'hello (world)'
hello world
此外,\K
允许可变长度的后视:
$ echo foooooo bar | grep -oP "(?<=foo+) \Kbar"
grep: lookbehind assertion is not fixed length
$ echo foooooo bar | grep -oP "foo+ \Kbar"
bar
关于regex - '\K' 在此正则表达式中意味着什么?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/33573920/