copy every line from a text file that contains a number greater than 5000

Question

Hi I've tried many solutions to similar questions and none have seemed to work for me. I have a text file where each line has an undefined length of numbers after the string " length_ ". How can I select out all the lines where that number is equal to or greater than 5000? This has been the cleanest looking code attempt I’ve tried so far, but it still just produces an empty file (even though file1 definitely contains lines with numbers greater than 5000)

grep --regexp="length_\"[5-9][0-9]\{3,\}\"" file1.txt > file2.txt

example info within input text file:
/file/path/xx00:>TEXT_1_length_81903_cov_10.5145_
/file/path/xx01:>TEXT_2_length_348971_cov_13.6753_
/file/path/xx02:>TEXT_3_length_4989_cov_11.9516_
/file/path/xx03:>TEXT_4_length_29811_cov_13.7948_
/file/path/xx03:>TEXT_5_length_2567_cov_13.7948_

desired example info within output text file:
/file/path/xx00:>TEXT_1_length_81903_cov_10.5145_
/file/path/xx01:>TEXT_2_length_348971_cov_13.6753_
/file/path/xx03:>NODE_4_length_29811_cov_13.7948_

Answer 1

Here's one way, using awk, to print lines from a file that contain a number after the string "length_" that is less than or equal to 5000:

awk '{sub("length_", "", $0); if ($0 <= 5000) { print "length_"$0 } }' input

It simply tells awk to strip off the "length_" string, then compare the remaining part of the line to 5000; if it's less than or equal to 5000, print "length_" and the remainder of the line. Your Q's subject line says (at the time) "greater than 5000", so if that's the actual desire, simply change the comparison in awk:

awk '{sub("length_", "", $0); if ($0 > 5000) { print "length_"$0 } }' input

---

Given the actual file format, the awk command can be simplified considerably:

awk -F_ '$4 > 5000' input

or

awk -F_ '$4 <= 5000' input

by telling awk to split the fields based on underscores, then comparing the fourth field to 5000. If the comparison is true, then (by default) print.

Answer 2

grep -E '_length_([5-9][0-9]{3}|[0-9]{5,})_' file1.txt > file2.txt

outputs lines containing:

• _length_ followed by either:
  • 5 - 9 and 3 more digits (5000-9999) or
  • 5 or more digits (10000+)
• followed by _.