Hi everyone,

I have two files which will be exactly same at first. After sometime there will be inserts in one file. My problem is how to reflect these changes in second file also.

I found out that any compare and merge utility would do the job like, GNU " sdiff " command. But the problem with sdiff is, it is an interactive tool. we have to tell the command what to do each time it finds a difference in the files. (Either merge the change or discard it by specifying 'l' , 'r' ..options)

do any one of you know how to automate this process.... or any other utility is available for doing this?

(sort with -m option is not what i want ..because i dont want to lose the order in the files)

Thanks in advance

cp firstfile secondfile
will ensure that any changes made to the first file are reflected in the second file.

hi perdarabo,

i am sorry to miss out an important point above.. My second file also can have inserts at the end but not in the middle...so if we do cp we will loose second file changes.

(to put it differently, i am looking at two files which are same at first but after sometime both will change)

will "clobber" the 2nd file. (clobber = completely replace/overwrite everything in "secondfile").

If you want to append data from firstfile, try , which appends the contents of firstfile to secondfile. Make sure there are two ">>" b/c only one ">" does the same thing as the above cp command. This is explained in good shell programming books under "input/output redirection".

Surely all that is going to do is attach the entire content of firstfile onto the end of second file rather than just what has been updated.

Doesn't he want to take two data files that start with the same content, update both files with different sets of data and merge those 2 files into 1 file that contains all the data without replicating anything ?? (If you follow what I mean..)

I'm not sure if there are any UNIX commands that could do it, but I would look at using Perl or similar...

You're right. I didn't read his post clearly enough. The rsync utility can help: http://rsync.samba.org (is usually avail in most distros as well) It works locally as well as remotely and can use ssh for added security.

Perhaps take a look at comm.

comm -23 prints only lines in the first file but not in the second