Understanding a regex


 
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# 1  
Old 03-02-2012
Understanding a regex

Hi,

Please help me to understand the bold segments in the below regex.
Both are of same type whose meaning I am looking for.
Code:
find . \( -iregex './[0-9]\{6,10\}.[0-9]/src' \) -type d -maxdepth 2

Output:
Code:
./20111210.0/src

In continuation to above:
Code:
sed -e 's|./\([0-9]*.[0-9]\{1,3\}\).*|\1|g'

Output:
Code:
20111210.0

What I could gather:
In find it looks for directories starting with 0-9 followed by . (dot) & again the same pattern. Has a directory named src inside it.
The { confuses me.

In sed same thing.

---------- Post updated at 01:00 PM ---------- Previous update was at 12:42 PM ----------

Googling hints that it's probably the count.
Am I on right track?

Last edited by Franklin52; 03-02-2012 at 04:35 AM.. Reason: Please use code tags for code and data samples, thank you
# 2  
Old 03-02-2012
In general this would mean \{m,n\}a minimum of 'm' numbers and maximum of 'n' numbers in length. Its actually the range. So

[0-9]\{6,10\} - this matches numbers of atleast 6 and atmost 10 in length, hence it matched: 20111210. If in case you have a dir which is say 20112 - this would not get displayed as it has totally/length 5 numbers, whereas our condition says to find with minimum of 6 numbers and a max of 10. Similarly in Sed

.[0-9]\{1,3\} after a dot find for number which is of minimum 1 and a max of 3 in length
# 3  
Old 03-02-2012
yes you are right track Smilie look at this
Code:
# touch abcdddde
# find . -regextype posix-basic -regex './[a-c]*d\{4\}e'
./abcdddde
# echo "./abcdddde"|sed -n '/[a-c]*d\{4\}e/s/.*/OK/p'
OK

# 4  
Old 03-02-2012
Thanks folks,
That explains it.
# 5  
Old 03-02-2012
usualy (in perl for example) u don't need to escape those
just {3}
or {6,10}
or {5,}
tip78
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