Efficient way to get n middle lines from a very big file

Question

I have a big file around 60GB.

I need to get n middle lines of the file. I am using a command with head and tail like

tail -m file |head -n >output.txt
where m,n are numbers

The general structure of the file is like below with set of records (comma separated columns.) Each line can be of different length(say max 5000 chars).

col1,col2,col3,col4...col10

Is there any other way that I can take n middle lines with less time, because the current command is taking lot of time to execute?

Answer 1

With sed you can at least remove the pipeline:

sed -n '600000,700000p' file > output.txt

will print lines 600000 through 700000.

Answer 2

awk 'FNR>=n && FNR<=m'

followed by name of the file.

Answer 3

It might be more efficient to use the split utility, because with tail and head in pipe you scan some parts of the file twice.

Example

split -l <k> <file> <prefix>

Where k is the number of lines you want to have in each file, and the (optional) prefix is added to each output file name.