Understanding a regex

Shell Programming and Scripting
1

Hi,

Please help me to understand the bold segments in the below regex.
Both are of same type whose meaning I am looking for.

find . \( -iregex './[0-9]\{6,10\}.[0-9]/src' \) -type d -maxdepth 2

Output:

./20111210.0/src

In continuation to above:

sed -e 's|./\([0-9]*.[0-9]\{1,3\}\).*|\1|g'

Output:

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?

2

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

yes you are right track :wink: look at this

# 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

Thanks folks,
That explains it.

5

usualy (in perl for example) u don't need to escape those
just {3}
or {6,10}
or {5,}