replace a line in files present in different folders shell script

I have a common line in different files present in different folders. how can i replace that line with some other line using shell script sed command in all the files of the folders ?

Eg: t="/home/file.txt" present in one of the file in a folder same line is present in different file of differnt folder

I have to replace it with t="/desk/file1.txt" . so where can i execute the sed command whether outside the folder ?

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Link to original article：https://stackoverflow.com/questions/47566414/replace-a-line-in-files-present-in-different-folders-shell-script