use linux commands to extract lines from a file by line number

many times we want to extract certain lines from a file


tommy@tommy-ThinkPad-T420:~/Datasets$ cat selectlines.txt 
1 one
2 two
3 three
4 four
5 five
6 six
7 seven
8 eight
9 nine
10 ten

# control + D to indicate the end of the file

extract the first 3 lines

tommy@tommy-ThinkPad-T420:~/Datasets$ sed -n  '1,3 p'  selectlines.txt 

1 one

2 two

3 three

http://stackoverflow.com/questions/83329/how-can-i-extract-a-range-of-lines-from-a-text-file-on-unix

This is 1-indexed. -nsuppresses echoing the input as output, which we clearly don't want; the numbers indicate the range of lines to make the following command operate on; the command p prints out the relevant lines.

if you have a very large file, add a quit argument, otherwise the sed program will scan to the end of the file

sed -n '16224,16482p;16483q' filename

or use awk

tommy@tommy-ThinkPad-T420:~/Datasets$ awk 'NR==1,NR==3' selectlines.txt 

1 one

2 two

3 three

or combine head and tail

extract  from line 16224 to 16482

head -16428 < file.in | tail -259 > file.out

or cat file.txt | head -n 16482 | tail -n 258

http://linuxcommando.blogspot.com/2008/04/using-awk-to-extract-lines-in-text-file.html

Using awk, to print every second line counting from line 0 (first printed line is line 2):
$ awk '0 == NR % 2'  somefile.txt
Line 2
Line 4
To print every second line counting from line 1 (first printed line is 1):
$ awk '0 == (NR + 1) % 2'  somefile.txt
Line 1
Line 3