bash 脚本 - 无法在值中设置带有双引号的变量
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bash script - unable to set variable with double quotes in value
提问by noober
Need help in fixing this bash script to set a variable with a value including double quotes. Somehow I am defining this incorrectly as my values fooand barare not enclosed in double quotes as needed.
需要帮助修复此 bash 脚本以设置包含双引号的值的变量。不知何故，我将其错误地定义为我的值foo，bar并且没有根据需要用双引号括起来。
My script thus far:
到目前为止我的脚本：
#!/usr/local/bin/bash
set -e
set -x
host='127.0.0.1'
db='mydev'
_account="foo"
_profile="bar"
_version=
_mongo=$(which mongo);
exp="db.profile_versions_20170420.find({account:${_account}, profile:${_profile}, version:${_version}}).pretty();";
${_mongo} ${host}/${db} --eval "$exp"
set +x
Output shows:
输出显示：
+ host=127.0.0.1
+ db=mydev
+ _account=foo
+ _profile=bar
+ _version=201704112004
++ which mongo
+ _mongo=/usr/local/bin/mongo
+ exp='db.profile_versions_20170420.find({account:foo, profile:bar, version:201704112004}).pretty();'
+ /usr/local/bin/mongo 127.0.0.1/mydev --eval 'db.profile_versions_20170420.find({account:foo, profile:bar, version:201704112004}).pretty();'
MongoDB shell version: 3.2.4
connecting to: 127.0.0.1/mydev
2017-04-22T15:32:55.012-0700 E QUERY [thread1] ReferenceError: foo is not defined :
@(shell eval):1:36
What i need is account:"foo", profile:"bar"to be enclosed in double quotes.
我需要的是account:"foo"，profile:"bar"用双引号括起来。
回答by Robert Seaman
In bash (and other POSIX shells), the following 2 states are equivalent:
在 bash（和其他 POSIX shell）中，以下 2 个状态是等效的：
_account=foo
_account="foo"
What you want to do is to preserve the quotations, therefore you can do the following:
您想要做的是保留报价，因此您可以执行以下操作：
_account='"foo"'
回答by Charles Duffy
Since part of what you're doing here is forming JSON, consider using jq-- which will guaranteethat it's well-formed, no matter what the values are.
由于您在这里所做的部分工作是形成 JSON，请考虑使用jq-- 这将保证它的格式正确，无论值是什么。
host='127.0.0.1'
db='mydev'
_account="foo"
_profile="bar"
_version=
json=$(jq -n --arg account "$_account" --arg profile "$_profile" --arg version "$_version" \
'{$account, $profile, version: $version | tonumber}')
exp="db.profile_versions_20170420.find($json).pretty();"
mongo "${host}/${db}" --eval "$exp"
This makes jqresponsible for adding literal quotes where appropriate, and will avoid attempted injection attacks (for instance, via a version passed in $1containing something like 1, "other_argument": "malicious_value"), by replacing any literal "in a string with \"; a literal newline with \n, etc -- or, with the | tonumberconversion, failing outright with any non-numeric value.
这使得jq负责在适当的地方添加文字引号，并通过将字符串中的任何文字替换为;来避免尝试注入攻击（例如，通过传入的$1包含类似内容的版本1, "other_argument": "malicious_value"）；带有, 等的文字换行符- 或者，通过转换，任何非数字值都完全失败。"\"\n| tonumber
Note that some of the syntax above requires jq 1.5 -- if you have 1.4 or prior, you'll want to write {account: $account, profile: $profile}instead of being able to write {$account, $profile}with the key names inferred from the variable names.
请注意，上面的某些语法需要 jq 1.5——如果您有 1.4 或更低版本，您将需要编写{account: $account, profile: $profile}而不是能够{$account, $profile}使用从变量名称推断出的键名称进行编写。
回答by PSkocik
When you need to use double quotes inside a double quoted string, escape them with backslashes:
当您需要在双引号字符串中使用双引号时，请使用反斜杠将它们转义：
$ foo="acount:\"foo\"" sh -c 'echo $foo'
acount:"foo"
