How can I delete every Xth line in a text file?

Question

Consider a text file with scientific data, e.g.:

5.787037037037037063e-02 2.048402977658663748e-01
1.157407407407407413e-01 4.021264347118673754e-01
1.736111         


        

Answer 1

You can use a awk and a shell script. Awk can be difficult but...

This will delete specific lines you tell it to:

nawk -f awkfile.awk [filename]

awkfile.awk contents

BEGIN {
if (!lines) lines="3 4 7 8"
n=split(lines, lA, FS)
for(i=1;i<=n;i++)
 linesA[lA[i]]
}
!(FNR in linesA)

Also I can't remember if VIM comes with the standard Ubuntu or not. If not get it.

Then open the file with vim vim [filename]

Then type

:%!awk NR\%2 or :%!awk NR\%2 

This will delete every other line. Just change the 2 to another integer for a different frequency.