I want with sed to replace what is in [….] with target key=new_string
more /tmp/file
my.uri=http://[linux123]:8080
we try this
key=new_string
sed s"/\[*\]/$key/g" /tmp/file
but file not changed
more file
my.uri=http://[linux123]:8080
what is wrong with my sed?
Expected results should be ( without Square brackets )
more file
my.uri=http://new_string:8080
First of all, you have to ensure that your key variable does not contain any characters with special meaning for your sed command, like for example / which is the default separating character for the sed substitution. In such a case you could use a different character, for example like this "s@pattern@replacement@g" file.
Then you need to match from an opening until the corresponding closing bracket. That would be \[.*\] but sed is greedy: In case your line contains [text1] text2 [text3], sed will match all of this. So you need to define, instead of .*, any character which is not a closing bracket, zero or more times: [^]]*.
Note that in the above, we don't need to escape (\]) the bracket in the middle, because sed awaits for at least one character to exclude after the caret (^), so it will not misread this as the closing bracket of the list of the excluded characters, but as a literal bracket.
Now if you want to make the change in-place, you can use -i like described in this post. But first test without -i, check a part of the output to see if it looks good.
So this sed is expected to work for your case:
sed -i "s/\[[^]]*\]/$key/g" file
Your regexp is missing a '.' before '*'. If you are sure, that there is only one opening, and one closing bracket, then this should work:
sed "s/\[.*\]/$key/g" /tmp/file
This prints to the stdout, if you want to edit in-place, use sed -i.
\[[^]]*\]. This is a regular expression, to be used in sed. If you had a star alone instead of[^]]*it would be a shell glob expression (matching anything).