Insert a line as the first line into a very huge file

shriek · #1 (**permalink**) 03-07-2005

Hello,

I need to insert a line (like a header) as the first line of a very huge file (about 3 ml rows). I am able to do it with sed, but redirecting the output and creating a new file takes quite some time. I was wondering if there was a more efficient way of doing it?

Any help would be greatly appreaciated.

Rds
Shriek

bhargav · #2 (**permalink**) 03-07-2005

Let 's say header is redirected to a file 'tmp'
If larger file is 'file1'

what about

Code:

cat tmp file1 > file2
mv file2 file1

It may be faster than 'sed'

reborg · #3 (**permalink**) 03-08-2005

Or rather than using sed you could use ed, you dont redirect the output then, but I don't know if it would be any quicker.

Ygor · #4 (**permalink**) 03-09-2005

perl -pi -e 'print "header\n" if $.==1' file1

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