merging files in linux
 

Hi all,

Assume that i am having two files file1 and file2.

these were the contents of file1

Name=Dinesh
Age=24
sex=male
character=good
profession=admin

these were the contents of file2

Name=vino
Age=22
sex=female

Now i want to copy only the contents from file1 which were not in file2.

i.e. after copying my file2 content should look like this.

Name=vino
Age=22
sex=female
character=good
profession=admin

i.e. only the content which is not in file2 needs to be copied, remaining content should be undisturbed.

In linux is there a way to do this. If possible kindly post your suggestions.

Thanks in advance,
Dinesh.

A quick 'n dirty method:

...Provided none of the fields end in the character < followed by a space!

Note that the solution proposed by Ignotum per Ignoius assumes that your two files were literally named "file1" and "file2." If your actual names are different from those, the diff command should be written with the two file names following the -y option.

You can look at the output of man diff for a description of the diff command. (And, of course, man sed for a description of the stream editor into which the diff output is piped.)

Thanks for pointing that out: I'm a lazy typist... :hattip:

Hi Ignotum,

I used your code,this is the output.

root@dinesh-laptop:~# diff -y file1 file2 | sed '/< $/!s/=[^=]*=/=/g'
Name=vino
Age=22
sex=female
character=good <
profession=admin <

But the contents is not copied to file2. it remains the same.

...As I said, quick 'n dirty... :)

Filter out the extraneous angle brackets with another application of sed.

The alteration is pretty simple --- just redirect to a temporary file and then move that over the original file.

Here's a one-liner that should do what you want:

Test it first on some backup copies of your files, though!

Hi,

Thank you that works fine. But i have one doubt is it necessary to redirect the output to a hidden file.

if thats the case can you please explain me why we cant redirect to a regular file.

Good show.

The step of creating a temporary file is necessary --- you can't simply redirect the output of diff/sed to file2, as file2 is still being read line-by-line. However, it's not necessary to make the file hidden --- it's just my usual practice with temporary files.

You can redirect to a "regular" file: really, a hidden file is "regular" in every sense except that it's not (normally) listed by ls --- it doesn't have any special attributes in and of itself. The reason why (or at least one of the reasons why) I generally choose to hide temporary files containing redirected output is to reflect the fact that they exist only fleetingly as a stop-gap. You could just as easily have used an unhidden file. ...So yes, if it's bothering you, feel free to remove the period!

Alternative:

Hi grail,

Thanks for your reply,

i executed your code without redirecting to a file.and this is the output i got.

[root@localhost ~]# awk -F"=" 'NR == FNR{_[$1]=$0;next}!($1 in _){print _[$1]}' file1 file2



[root@localhost ~]#


Actually it looks empty.


Your suggestions please.

You can also try kdiff3, it is more user friendly! If you are using Kde, it will be
installed by default.

Sorry about that ... appears I was on drugs with my thinking :(
This seems to do what you want:

Another alternative using the diffs and sed earlier, I am just not sure if appending straight away might cause issues:
It seems to work for me but I am sure there is some kind of danger ... unless of course diff closes the file after outputting information??

I am sure some guru will let us know :)

Hi,


Thanks that works.Thanks to all especially to Ignotum.

...Happy to have helped. :)

All the best.