string 在 Bash 中比较两个字符串时出现“找不到命令”错误
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Getting "command not found" error while comparing two strings in Bash
提问by EpsilonAlpha
My whole Script is currently this:
我的整个脚本目前是这样的：
#!/bin/sh
clear;
blanko="";
# Dummy-Variablen
variable=Testvariable;
if [[$variable == $blanko]];
then
echo "Nichts da!"
else
echo $variable
fi
and if i enter
如果我输入
TestSelect.sh
i get
我明白了
/usr/bin/TestSelect.sh: line 6: [[Testvariable: command not found
Testvariable
how can i fix this?
我怎样才能解决这个问题？
回答by anubhava
This is problem:
这是问题：
if [[$variable == $blanko]];
Spaces are required inside square brackets, use it like this:
方括号内需要空格，像这样使用它：
[[ "$variable" == "$blanko" ]] && echo "Nichts da!" || echo "$variable"
回答by codeforester
On a related note, spaces are required around [ ]as well:
在相关说明中，周围也需要空格[ ]：
if [ "$variable" = "$blanko" ]; then
# more code here
fi
Note that variables do need to be enclosed in double quotes inside [ ]to prevent word splitting and globbing. Double quotes also help when either of the variables being compared is not set - shell will throw a syntax error otherwise.
请注意，变量确实需要用双引号括起来，[ ]以防止分词和通配符。当被比较的任何一个变量未设置时，双引号也有帮助 - 否则 shell 将抛出语法错误。
Look at the following post to understand why we need spaces around [ ]:
查看以下帖子以了解为什么我们需要空格[ ]：
Another related post that talks about other syntax elements that need spaces as well:
另一篇讨论其他需要空格的语法元素的相关文章：
Finally, this post talks about the difference between [[ ]]and [ ]:
最后，这篇文章谈到的区别[[ ]]和[ ]：
Related:
有关的：
回答by ankit
Just use #!/bin/bashon tope of script if you are using bash scripting like: if [[ $partition == "/dev/sda2" ]]; thento compare string and run script with ./scriptname.shor bash scriptname.sh
#!/bin/bash如果您使用 bash 脚本，则只需在脚本顶部使用，例如：if [[ $partition == "/dev/sda2" ]]; then比较字符串并使用./scriptname.sh或运行脚本bash scriptname.sh
回答by Danny
If your script runs on your local with /bin/bashbut not on your container with sh, then consider adding bash to your container by apk add --no-cache bash.
如果您的脚本在您的本地运行，/bin/bash但不在您的容器上运行sh，那么请考虑通过 .bash 将 bash 添加到您的容器中apk add --no-cache bash。
