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i have a text file as below. I want to change the lower string between foo and var to upper case.
foo nsqlnqnsslkqn var
lnlnl.
foo DkqdQ HNOQii var
my expected output is
foo NSQLNQNSSLKQN var
lnllnl.
foo DKQDQ HNOQII var
i have used a one liner using sed sed 's/\(\foo\).*\(\var\)/\U\1\2/' testfile.txt
but i get the following output
FOOVAR
lnlnl.
FOOVAR
934
Find and replace text within a file using sed command Use Stream EDitor (sed) as follows: sed -i 's/old-text/new-text/g' input.txt. The s is the substitute command of sed for find and replace. It tells sed to find all occurrences of 'old-text' and replace with 'new-text' in a file named input.txt.
The -e tells sed to execute the next command line argument as sed program. Since sed programs often contain regular expressions, they will often contain characters that your shell interprets, so you should get used to put all sed programs in single quotes so your shell won't interpret the sed program.
The toLowerCase() method converts the string specified into a new one that consists of only lowercase letters and returns that value. It means that the old, original string is not changed or affected in any way.
You can use \U to make something become upper case:
$ sed 's/.*/\U&/' <<< "hello"
HELLO
And \E to stop the conversion:
$ sed -r 's/(..)(..)(.)/\U\1\E\2\U\3/' <<< "hello"
HEllO
In your case, just catch the blocks and place those \U and \E accordingly:
$ sed -r 's/(foo )(.*)( var)/\1\U\2\E\3/' file
foo NSQLNQNSSLKQN var
lnlnl.
foo DKQDQ HNOQII var
(foo )(.*)( var) catches three blocks: foo, the next text and var.\1\U\2\E\3 prints them back, upcasing (is it a verb?) the second one (\U) and using the current case (\E) for the 3rd.Without -r, to make it more similar to your current approach:
sed 's/\(foo \)\(.*\)\( var\)/\1\U\2\E\3/' file
So you can see that you were not catching the .* block, so you were printing back just foo and var.
From the manual of sed:
\L Turn the replacement to lowercase until a \U or \E is found,
\l Turn the next character to lowercase,
\U Turn the replacement to uppercase until a \L or \E is found,
\u Turn the next character to uppercase,
\E Stop case conversion started by \L or \U.
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