I am creating a script in which I have to note down the size of the files which are in different directory. Suppose:- In log dir : A1.txt A2.txt A3.txt A4.txt and in dat directory" A4.txt A5.txt A6.txt A2.txt A1.txt A3.txt I want to create a script which can give me the file size of those files which have the same name in both the folders. For this I have create a for loop. First for loop do the ls and then there is a second internal for loop which runs under the first for loop which checks whether the file which is in the log directory exists in the dat directory, if it matches, it stores the result in the result.txt file having the file size of both the files. The problem I am having with for loop is its skipping some files while iterating through the list of the files. Please post an example so that I have some idea what I am missing. Thanks.