data manipulation in the file

[Peter Nikitka]

Hi,

>>
since i dont understand perl.
<<

That does not matter, IMHO: There may be solutions in other languages, you won't understand, as well.

We do not have your answer yet: Is the change of these characters required once in that file or in every line of it?
More questions:
- What about lines with less than 7 characters?
- Will newline charactes count?

All line change:
nawk -v str=NEW '{print substr($0,1,4)""str""substr($0,8)}' infile

mfG Peter

[Dennis Handly]

>Peter: What do you mean by "without opening"?
>Ralph: I don't think that you can modify data in a file without opening it

I can only assume that Reen@ meant the Windows open (run an editor or other magic program based on suffix) and not the nerd definition of open a file.

[James R. Ferguson]

Hi:

Dennis wrote:

> I can only assume that Reen@ meant the Windows open (run an editor or other magic program based on suffix) and not the nerd definition of open a file.

Yes, of course. Unless you can *open* a file, how else can you expect any process to *read* a stream of octets to perform any match and/or substitution!?!

Depending upon the language, an implicit open() may be performed with a read() or write(), but that is purely under-the-covers slight-of-hand. The '-p' Perl switch is actually performing an open() for the file name(s) specified as arguments to the script so this too counts as an open(). Ditto for the 'sed' and the 'awk' solutions.

Regards!

...JRF...

[Reen]

Ok..
I have attached the file.
I dont want the change to be done for all lines.
Only once i want the 5th,6th and 7th character to be replaced with say "AIR".
I have to do this change for many files. And these 3characters will be different for different files.
So, i wont know the characters to be replaced before hand itself.

[Dennis Handly]

>I dont want the change to be done for all lines.

(Then you say you want it done for only the first line.)

$ sed -e '1s/^\(....\).../\1AIR/' file

This will create a new file, changing only the first line. You would need to save the output and rename it to the original.

for file in $*; do
sed -e '1s/^\(....\).../\1AIR/' $file > $file.new
mv $file.new $file
done

If the original is read-only, use "mv -f" above.

[Reen]

Dennis,
what does ^\(....\)... mean?
is it the range?
5th,6th and 7th character....how do i specify?:(

[Dennis Handly]

>what does ^\(....\)... mean?

I mentioned that initially. \( & \) assigns a number for the pattern inside, to the first 4 chars, then selects the next 3. "." means it can be an arbitrary char.

Then it puts the first 4 back with "\1", then your replacement string "AIR".

[Reen]

Hi all,
I got a simple solution for this.

cat file|cut -c5-7|read VAR1
sed "s/$VAR1/AIR/" file

will work out fine.
Thanks a lot for the help and patience.
I will do the further procedures and close the thread.:-)

[Reen]

2 line command will work out

[Dennis Handly]

>cat file|cut -c5-7|read VAR1
sed "s/$VAR1/AIR/" file

This depends on columns 5-7 of the first record not appearing ANYWHERE in the rest of the file.

My script only changes that one line and only those columns. You can fix part of it by using "1s/$VAR1/AIR/" and change cat to "head -1".