How to Delete Lines Longer Than XY Using sed

sed

How can i delete a line if it is longer than e.g.: 2048 chars?

sed '/^.\{2048\}./d' input.txt > output.txt

You could use sed. The following would remove lines that are 3 characters long or smaller:

sed -r '/^.{,3}$/d' filename

In order to save the changes to the file in-place, supply the -i option.

If your version of sed doesn't support extended RE syntax, then you could write the same in BRE:

sed '/^.\{,3\}$/d' filename

which would work with all sed variants.

You could also use awk:

awk 'length($0)>3' filename

Using perl:

perl -lne 'length()>3 && print' filename

Typical job for awk:

awk 'NR == 1 {first = $1}; $1 - first <= 10' < file

Or to do it only for the last line:

awk 'NR == 1 {first = last = $0; next}
     {print last; last = $0}
     END {if (NR && last - first <= 10) print last}' < file