Bash：迭代地图的正确方法
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Bash: Correct way to Iterate over Map
提问by Lars Tackmann
In Bash I can create a map(hashtable) with this common construction
在 Bash 中，我可以使用这种常见构造创建地图（哈希表）
hput() {
eval """"=''
}
hget() {
eval echo '${'""'#hash}'
}
and then use it like this:
然后像这样使用它：
hput capitals France Paris
hput capitals Spain Madrid
echo "$(hget capitals France)"
But how do I best iterate over the entries in the map ?. For instance, in Java I would do:
但是我如何最好地迭代地图中的条目？例如，在 Java 中我会这样做：
for (Map.Entry<String, String> entry : capitals.entrySet()) {
System.out.println("Country " + entry.getKey() + " capital " + entry.getValue());
}
is there a common way of accomplishing something similar in Bash ?.
在 Bash 中是否有一种通用的方法来完成类似的事情？
回答by ghostdog74
if you have bash 4.0 , you can use associative arrays. else you can make use of awks associative arrays
如果您有 bash 4.0，则可以使用关联数组。否则你可以使用 awks 关联数组
回答by Paused until further notice.
Here's one way to do it:
这是一种方法：
for h in ${!capitols*}; do indirect=$capitols$h; echo ${!indirect}; done
Here's another:
这是另一个：
for h in ${!capitols*}; do key=${h#capitols*}; hget capitols $key; done
And another:
还有一个：
hiter() {
for h in $(eval echo '${!''*}')
do
key=${h#*}
echo -n "$key "
hget $key
done
}
hiter capitols
France Paris
Spain Madrid
By the way, "capitol" is a building. A city is referred to as a "capital".
顺便说一下，“国会大厦”是一座建筑物。一个城市被称为“首都”。
回答by ZyX
hkeys() {
set | grep -o "^[[:alnum:]]*=" | sed -re "s/^(.*)=/\1/g"
}
for key in $(hkeys capitols) ; do
echo $key
done
And your hget function is wrong. Try this:
你的 hget 函数是错误的。尝试这个：
hput capitols Smth hash
hget capitols Smth
Second command should return the string hash, but it returned nothing. Remove ?#hash? string from your function.
第二个命令应该返回字符串哈希，但它什么都不返回。删除 ?#hash? 函数中的字符串。
Also, echo "$(hget capitols France)"is ambigious. You can use hget capitols Franceinstead.
还有，echo "$(hget capitols France)"暧昧。你可以hget capitols France改用。
