blocks|key|1764682|text|把后背移开。它试图以shell命令的形式执行kubectl的输出。您希望回显$line，而不是将其作为命令执行的结果。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1764683|kubectl+get+ns+%7C+while+read+-r+line;+do++
++++echo+"$line"+%7C+grep+Term+%7C+cut+-d'+'+-f1
done|code-block|syntax|javascript|1764684|似乎根本没有必要使用while+read，只需将kubectl输送到grep|1764685|kubectl+get+ns+%7C+grep+Term+%7C+cut+-d'+'+-f1|1764686|entityMap^0|M|7|12|5|0|0|A|A|O|7|Y|4|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|13|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|P|$]]

Ger rid of the backticks. It's trying to execute the output of <code>kubectl</code> as a shell command. You want to echo <code>$line</code>, not the result of executing it as a command.

<pre><code>kubectl get ns | while read -r line; do 
 echo "$line" | grep Term | cut -d' ' -f1
done
</code></pre>

There doesn't really seem to be a need to use <code>while read</code> at all, just pipe <code>kubectl</code> to <code>grep</code>

<pre><code>kubectl get ns | grep Term | cut -d' ' -f1
</code></pre>

blocks|key|2776916|text|parameter+expansion可能是您想要/需要的，而不是将grep和cut嵌入到while+read循环中。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2776917|#!/usr/bin/env+bash

kubectl+get+ns+%7C+while+IFS=+read+-r+line;+do++
++[[+$line+==+Term+]]+&&+ns=${line%25+*}
++echo+"$ns"
done|code-block|syntax|javascript|2776918|根据模式匹配，您可能需要*Term*|2776919|entityMap^0|0|J|Y|4|13|3|19|A|0|0|C|6|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]|$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|N|$]]

A <code>parameter expansion</code> might be what you want/need, instead of embedding <code>grep</code> and <code>cut</code> inside a <code>while read</code> loop.

<pre><code>#!/usr/bin/env bash

kubectl get ns | while IFS= read -r line; do 
 [[ $line == Term ]] &amp;&amp; ns=${line% *}
 echo "$ns"
done
</code></pre>

Depending on the pattern match, you might need <code>*Term*</code>

blocks|key|665879|text|grep和cut的任何组合(以及head、tall等以及sed)都建议在Awk中重新实现。保存一个外部流程是一个小的优化，但这通常会带来更多的简单改进。例如，regex应该覆盖整个行，还是应该只在第一个字段中查找匹配项？当然，用grep也不是不可能的，但是在Awk中非常容易。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|665880|kubectl+get+ns+%7C
awk+'/Term/+{+print+$1+}'|code-block|syntax|javascript|665881|如果您只想在第一个字段中查找Term，那就是'$1+~+/Term/+{+...|665882|您可以使用管道将其扩展到|665883|...+%7C+xargs+./delete-kube-ns.sh|665884|如果这是你的最终目标。|665885|entityMap^0|0|4|5|3|G|4|L|4|S|3|36|4|0|0|E|4|M|I|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]|$9|13|A|14|B|C]|$9|15|A|16|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|17|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|18|8|@$9|19|A|1A|B|C]|$9|1B|A|1C|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|1D|8|@]|D|@]|E|$]]|$1|O|3|P|5|H|7|1E|8|@]|D|@]|E|$I|J]]|$1|Q|3|R|5|6|7|1F|8|@]|D|@]|E|$]]|$1|S|3|-4|5|6|7|1G|8|@]|D|@]|E|$]]]|T|$]]

Any combo of <code>grep</code> and <code>cut</code> (and <code>head</code>, <code>tall</code>, etc, as well as <code>sed</code>) suggests a reimplementation in Awk. Saving one external process is a minor optimization, but this often invites additional simple improvements. For example, should the regex cover the whole line, or is it only really supposed to look for matches in the first field? That's not impossible with <code>grep</code>, either, of course, but quite easy in Awk.

<pre class="lang-sh prettyprint-override"><code>kubectl get ns |
awk '/Term/ { print $1 }'
</code></pre>

If you only wanted to look for <code>Term</code> in the first field, that's <code>'$1 ~ /Term/ { ...</code>

You can extend this with a pipe to 

<pre><code>... | xargs ./delete-kube-ns.sh
</code></pre>

if that's your end goal.

blocks|key|2776974|text|有了你的建议，我实际上可以实现我想要做的事情。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2776975|kubectl+get+ns+%7C+awk+'/Term/+{+print+$1+}'+%7C+while+IFS=+read+-r+line;+do
+++~/bin/kill-kube-ns.sh+$line
done
Killed+namespace:+configmap-4500
Killed+namespace:+configmap-5062
Killed+namespace:+configmap-5526
Killed+namespace:+configmap-5817
Killed+namespace:+configmap-6143|code-block|syntax|javascript|2776976|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

With your suggestion I actually could achieve what I intended to do

<pre><code>kubectl get ns | awk '/Term/ { print $1 }' | while IFS= read -r line; do
 ~/bin/kill-kube-ns.sh $line
done
Killed namespace: configmap-4500
Killed namespace: configmap-5062
Killed namespace: configmap-5526
Killed namespace: configmap-5817
Killed namespace: configmap-6143
</code></pre>

In reference to <a href="https://stackoverflow.com/questions/4651437/how-do-i-set-a-variable-to-the-output-of-a-command-in-bash/41236640#41236640">this question</a> I still struggle the following single-liner to work

<pre><code>kubectl get ns | while read -r line; do echo `$line | grep Term | cut -d' ' -f1`; done
</code></pre>

I would expect to print out the result of <code>$line | grep Term | cut -d' ' -f1</code> however it prints out an empty line (<code>echo</code>) and then executes the result of <code>$line | grep Term | cut -d' ' -f1</code> 

<pre><code>bash: NAME: command not found

bash: cert-manager: command not found

bash: configmap-4262: command not found

bash: configmap-4430: command not found

</code></pre>

Same results with a slightly different approach:

<pre><code>kubectl get ns | while read -r line; do ns=`$line | grep Term | cut -d' ' -f1`; echo $ns; done
</code></pre>

What I actually want to achieve is to use the result of <code>$line | grep Term | cut -d'</code> as an input of a shell script e.g.

<pre><code>do ns=`$line | grep Term | cut -d' ' -f1`; ./delete-kube-ns.sh $ns;
</code></pre>

or

<pre><code>$line | grep Term | cut -d' ' -f1` | xargs ./delete-kube-ns.sh
</code></pre>

How to output the result of a chain of commands for a given input with bash

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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