Regular expression to Grep for a n digit number

somupl86 · 11-23-2010, 05:15 AM

Hi,

I just want to grep for a n digit number followed by M alphabet.

Generally for a three digit number i can give

grep [0-9][0-9][0-9]M , but if the digits are increasing it is tough to represent them.

Any help in this regard.

Thanks in Advance,

Soma Sekhar Kalla

syg00 · 11-23-2010, 05:30 AM

Look at "grep -E" (nee egrep) - you can specify a specific number, or repetition. I also prefer classes, as in [[:digit:]] - doesn't really matter here, but may in other classes/uses.
See the manpage.

somupl86 · 11-23-2010, 05:58 AM

Actually my question is not with grep, i need a regular expression that mataches 9 digit number followed by a letter M.

Thanks,
Soma

devnull10 · 11-23-2010, 06:17 AM

Code:

[0-9]{9}M

somupl86 · 11-23-2010, 06:39 AM

No that is not working.

sycamorex · 11-23-2010, 06:58 AM

What about:

Code:

ls | grep -E '\<[0-9]{9}M\>'

devnull10 · 11-24-2010, 06:03 AM

You have to use egrep and surround with quotes.

Code:

$ echo "123M" | egrep '[0-9]{3}M'
123M

sycamorex · 11-24-2010, 06:11 AM

Quote:

Originally Posted by devnull10

You have to use egrep and surround with quotes.

Code:

$ echo "123M" | egrep '[0-9]{3}M'
123M

The problem with it is that it will also match:

Code:

$ ls | egrep '[0-9]{3}M'
23456M
333M
3453454524554M
3456M
4444M
456M
55555M
666666M
777777M
945454555555M
999999999M

I think this is what the OP is after:

Code:

$ ls | egrep '\<[0-9]{3}M\>'
333M
456M