How do I generate a list of the characters occurring before a certain character only in lines that contain another certain character using regex?

Question

I know that's super confusing (total noob-sorry!). To clarify, I have a text file that looks like this:

407-OL?
408-2-OL?
408-OL?
418-het?
420-1 and 2- OL?
429-2-left unscored?
430-2-left both unscored?
431-1 and 2- Ri??
436-1-just homozygote?
444-2-het? ins. both
456-2-ins 246 despite slight OL
456-1-ins 245 (weaker)
457-2-Ri?

I want it to return the numbers on the left (before the dash), but only for lines that contain a question mark. In other words, I want this to be the output:

Any suggestions would be amazingly helpful! Thank you!

To clarify further, there is a new line before each number with a dash: 407-OL? '\n' 408-OL? '\n' etc. etc.
After reading the question title, I just realized how awkward translating sed to English would be.

jippie · Accepted Answer · 2012-05-06 17:19:13Z

up vote 1 down vote accepted

Probably easiest method: cat some_file | grep '?' | cut -d'-' -f1

cat somefile => feed the contents of some_file into the pipe
grep '?' => filter only lines containing a ?
cut -d'-' -f1 => divide the string into fields with - as field separator, then print field #1

edited May 6 '12 at 17:19

answered May 6 '12 at 16:56

jippie
3,4021224

Fantastic! Thank you very much! It worked! – Atticus29 May 6 '12 at 17:02

3

Make a touch a then try again. Will not work anymore. ? is a wildcard character and should be escaped or quoted. – manatwork May 6 '12 at 17:04

I know what you mean, but I can't reproduce it. grep ? should be replaced by grep '\?', is that what you mean? – jippie May 6 '12 at 17:07

I mean “escape or quote”. So either grep \? or grep '?' or grep "?". Otherwise the shell will perform wildcard expansion and ? will be replaced with the list of matching files – all files in the current directory with single character long names. – manatwork May 6 '12 at 17:15

updated my answer – jippie May 6 '12 at 17:19

show 1 more comment

manatwork · Answer 2 · 2012-05-06 17:02:17Z

up vote 3 down vote

Typically a task for sed or awk:

sed -n '/?/s/-.*//p' some_file

awk -F- '/\?/{print$1}' some_file

answered May 6 '12 at 17:02

manatwork
9,65312847

asked	1 year ago
viewed	160 times
active	1 year ago

How do I generate a list of the characters occurring before a certain character only in lines that contain another certain character using regex?

2 Answers

Your Answer

Not the answer you're looking for? Browse other questions tagged grep regular-expression or ask your own question.

How do I generate a list of the characters occurring before a certain character only in lines that contain another certain character using regex?

2 Answers

Your Answer

Sign up or log in

Post as a guest

Not the answer you're looking for? Browse other questions tagged grep regular-expression or ask your own question.

Related