[英]bash : sed : regex in variable
I'm getting totally crazy with the following script. 我对以下脚本感到非常疯狂。
The following command works as expected : 以下命令按预期工作:
echo a | sed 's/a/b/'
Output : 输出:
b
But this script doesn't : 但是这个脚本没有:
test="'s/a/b/'"
echo a | sed $test
Output : 输出:
sed: -e expression #1, char 1: unknown command : `''
I should really be stupid, but I don't see what I am missing. 我真的应该是傻瓜,但我不知道我错过了什么。
Thanks, 谢谢,
test="'s/a/b/'"
echo a | sed $test
is equivalent to: 相当于:
test="'s/a/b/'"
echo a | sed "'s/a/b/'"
Obviously sed
doesn't understand the command with both "
and '
, It interprets '
as a command. You can use either one of them: 显然sed
并不理解带有"
和'
的命令,它将'
解释'
为命令。你可以使用其中任何一个:
test='s/a/b/'
Or 要么
test='s/a/b/'
you may want this: 你可能想要这个:
kent$ test="s/a/b/"
kent$ echo a | sed ${test}
b
or 要么
kent$ echo a | sed $test
b
or 要么
test=s/a/b/
This is because your double wrapping your string. 这是因为你的双重缠绕你的字符串。 test="'s/a/b'"
. test="'s/a/b'"
。 Sed then gets 's/a/b/'
as literal string. 然后,Sed将's/a/b/'
作为文字字符串。 You only want sed to receive s/a/b/
. 你只想要sed接收s/a/b/
。
You only need to wrap the string in one set of quotes , otherwise the inner set of quotes will be interpreted as part of the argument. 您只需要将字符串包装在一组引号中 ,否则内部引号集将被解释为参数的一部分。
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