Shell Programming and Scripting

Code:

firstfile >> secondfile

That's going to do naff all unless firstfile is an executable, in which case the output (stdout) from firstfile will be appended to secondfile.

You'll need

Code:

cat firstfile >> secondfile

Cheers
ZB

Thanks guys for all of your help.

what PaulC is exactly what i want.... I am giving an example data set here ... Ygor ur comm seems to point me in right direction but its not what i want..


At first both files contain

this is mango
this is apple
this is orange

After sometime first file will have inserts anywhere in the file (middle, last, etc..) and second file will have inserts only at the end of the file. so after sometime files might look like

file1

this is mango
this is banana
this is apple
this is grape
this is pineapple
this is orange
this is watermelon

file2

this is mango
this is apple
this is orange
this is cherry
this is lemon

OUTPU should be

this is mango
this is banana
this is apple
this is grape
this is pineapple
this is orange
this is watermelon
this is cherry
this is lemon


comm command seems to work differntly...more over it needs data to be sorted which i dont want to do.


So if any of you has any idea please pass it to me...thanks guys once again.

I think comm is what you want.

If you do the following

comm -12 firstfile secondfile >> thirdfile
comm -23 firstfile secondfile >> thirdfile
comm -13 firstfile secondfile >> thirdfile

That will give you lines common in both files, followed by lines
appearing only in the first file, followed by lines appearing only
in the second file.

Cheers
ZB

Perhaps use diff, but reformat the output...

diff file1 file2 | awk '/^[<>]/{print subst($0,3)}'

if you do not mind outfile being in sorted order you can try :

Code:

cat file? | sort | uniq > outfile

peace...

hello,

there are many ways to skin a cat. All good suggestions, however, the file cannot be sorted. One of the files will only have appended data , meaning the data is attached to the end of the file only. The other file will have data inserts that could appear all over the file. From the example given:

file1

this is mango
this is banana
this is apple
this is grape
this is pineapple
this is orange
this is watermelon

file2

this is mango
this is apple
this is orange
this is cherry
this is lemon

OUTPUT should be

this is mango
this is banana
this is apple
this is grape
this is pineapple
this is orange
this is watermelon
this is cherry
this is lemon

----------------------------------

the one solution given by appending the second file appears to be what you want. That is if this example holds true. The implementation needs a little going over.

If only one file, file1 will have modified data inserts all over its contents. This can be your primary file.
The second file does not really need to start off with any content since the only data modifications to be performed are to be done on the EOF. New data appended to back of file.
If you want to keep a copy of the original file then simply have three (3) files instead of two (2)

When the event happens that you merge these files say a specific time sceduled in cron or by size or what ever it is you simply take the 3rd files contents , which are the records originally appended to the back of the secondary file. ( which now is just a copy of the original file ) a 3rd file has the new records.
then simply append file2 to file1.


--------------------
original data
----
this is mango
this is apple
this is orange

--------------------
file 1 & file 2 look like

this is mango
this is apple
this is orange
-------------------------
file 3
null
-------------------------
file1 after inserts

this is mango
this is banana
this is apple
this is grape
this is pineapple
this is orange
this is watermelon

file2-----------------
simply a copy or dummy file showing appends
- don't really need except for archive purposes

this is mango
this is apple
this is orange
[this is cherry]
[this is lemon]

-------------------------------------
3rd / ( or 2nd ) file
this is cherry
this is lemon

OUTPUT file ( cat file2 >> file1 )

this is mango
this is banana
this is apple
this is grape
this is pineapple
this is orange
this is watermelon
this is cherry
this is lemon

Thanks a lot guys ... for so many replies.


Gary solutiioon is a good one. I think for now it works....

But i have a question what if we have been already given files in that format meaning we dont have control over the files from start...so then how anybody is gonna solve....

zazzybob solution also should work hypothetically but for some reason comm command is behavnig strangly... Its not giving what it should...

Once again thanks for all suggestions.