macOS Regular expression / sed question.

[Big Dave]

I can use sed to return a line that contains my search for regular expressions, but is there a way to only return the regular expression itself instead of the whole line?

sed -n '/[0-9][0-9]\.[0-9][0-9]/,p' file

The above one liner will return a whole line but I would like to return the item searched. Something like 99.99.

 

[kage207]

Check this article out.

http://www.gnu.org/software/sed/manual/sed.html#Execution-Cycle

 

[subsonix]

Check this article out.

http://www.gnu.org/software/sed/manual/sed.html#Execution-Cycle

That's GNU sed.

 

[Big Dave]

I think I can get close enough. If I use:

sed -n '/^.*[0-9][0-9]\.[0-9][0-9]/p' file

The first field is my desired target. I can grab it with awk from there.

 

[chown33]

The whole thing can be done in awk.

awk 'match($0,"[0-9][0-9]\.[0-9][0-9]")  { print substr($0,RSTART,RLENGTH) }' \
  data.txt

File data.txt:

I paid 12.34 for ten ducklings.
I sold them for 23.95 each.
What was the profit?

If a kangaroo travels 42.50 furlongs 
in 10.39 fortnights, does its velocity
exceed that of a score of African swallows
transporting 38.30 cubic inches of coconuts?

Output:

12.34
23.95
42.50
10.39
38.30

Or use perl's tagged regex'es:
http://www.tjhsst.edu/~dhyatt/perl/exA.html

 

[randian]

That's GNU sed.

Which I'm pretty sure Apple uses.

 

[subsonix]

FWIW I usually use grep -oE for this, the -o flag fetches only the part that matches the pattern, -E uses extended regex. Not sure if it will help you here but..

Example:

grep -oE "[0-9][0-9]\.[0-9][0-9]" text.txt

Will isolate numbers like 99.99 from text.txt.

Which I'm pretty sure Apple uses.

OS X is a BSD, they use BSD sed.

 

[Big Dave]

Thanks for the help everyone!

 

[-RATBOY-]

Simplified: ^\d{2}\.\d{2}$

This declares a start and end and must match a numeric value

 

[mfram]

Simplified: ^\d{2}\.\d{2}$

This declares a start and end and must match a numeric value

No, that expression says it matches only a line which contains the numeric value, but nothing else.

Thus it matches:
15.21

But not:
That costs 15.21!