I have an very big sql file that I cant open in a gui editor. I need to replace the string
'user1'@'localhost' (note the ` character) by 'user2'@'localhost' but i am having troubles finding the right syntax for sed command.
I can get the strings to replace correcly using the following grep command:
grep -w 'user1`@`localhost'
Any help please?
Thank you.
I thought of a more general solution than as your question asks for.
Let's imagine you need to find a string based on your regular expression search criteria. You'd like to replace only a part of it, and leave the other matching parts unchanged.
To demonstrate with an example:
echo "'some-name'@'some-host'" | sed -r "s/(')([^']+)('@'[^']*')/1user23/g"
will display:
'user2'@'some-host'
The sed command performs the replacement by using the s/search-regexp/replacement/g syntax. In our case:
(') matches the first single quote. This is trivial, but could be more complex. It represents the part of the string before the replacement. sed assigns the value of this sub-expression to the special variable 1.([^']+) matches the user name. Basically any character starting from the previous position that is not a quote. sed assigns the value of this sub-expression to the special variable 2.('@'[^']*') matches the '@'host-name' part. Similarly to the previous sub-expression, a quote, a @, a quote again and any character that is not a quote and then a quote at the end. sed assigns the value of this sub-expression to the special variable 3.The replacement part will replace anything that matched the search-regexp. By using the variables shown above, we can replace the user name and leave the other regions intact. 1 + your new user name + 3 will produce the desired result. Thus:
1user23
Results in:
2 is intentionally not used, because we replace the user name)'@ and the host name in quotes).If you cat your script file and pipe it to the sed command, you should get the desired result.
