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Quick Sed Question

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# 1  
Old 09-26-2011
Quick Sed Question
Just want to know why when I do the following in sed, the required is not extracted.

Code:
echo "ab01cde234" | sed 's/[0-9]*$//'

result: ab01cde (Which is correct)

Code:
echo "ab01cde234" |sed 's/.*\([0-9]*\)$/\1/'

result: blank (was expecting 234)
or
Code:
echo "ab01cde234" |sed 's/.*\([0-9]\)*$/\1/'

result: blank (was expecting 234)

Am i missing something here? Also note that 234 can be has many digits, just need to extract the last section of the digits.

Thanks
Last edited by pludi; 09-26-2011 at 07:38 AM..
# 2  
Old 09-26-2011
you can try thisSmilie
Code:
echo "ab01cde234" |sed 's/.\{7\}\([0-9]*\)$/\1/'
234

.* --> covers all string and sed does not consider your remaining exp that ( \([0-9]*\)$ )

regards
ygemici
# 3  
Old 09-26-2011
Thanks ygemici, but the {7} is doing a fixed set of characters at the beginning of the string, is there any way just to extract the last set of digits, without fixing the initial character set.

Thanks
Ed
# 4  
Old 09-26-2011
Code:
echo "ab01cde234" |sed 's/.*[^0-9]//'

The above matches the longst string which ends in something which is not a member of [0-9]. It substitutes the match with "nothing". Thus it returns the rest of the line.

More precise would be to force it to start from the start of the line.
Last edited by pludi; 09-26-2011 at 08:24 AM..
# 5  
Old 09-26-2011
this one?
Code:
echo "ab01cde234" | sed 's/.*[a-z]\([0-9]*\)$/\1/g'

--ahamed
# 6  
Old 09-26-2011
Thks guys, the last two did the trick.

Many Thanks for your help on this.
# 7  
Old 09-26-2011
Quote:
Originally Posted by eo29
Thanks ygemici, but the {7} is doing a fixed set of characters at the beginning of the string, is there any way just to extract the last set of digits, without fixing the initial character set.

Thanks
Ed
Hi Ed
sed does not parse your expression for dynamic strings
if you has fixed string then it can be write with sed.
however you can use grep for your needs more sensiblely Smilie

Code:
echo "ab01cde234"|grep -o "[0-9]*$"
234

if you want to use sed , maybe you can try like this
Code:
echo "ab01cde234" | sed 's/.*[a-zA-Z]\([0-9][0-9]*\)[A-Za-z]*/\1/g'
234

or
Code:
echo "abca121a1b01cde23412zxxx1212aa" | sed 's/.*[a-zA-Z]\([0-9][0-9]*\)[A-Za-z]*/\1/g'
1212


Quote:
Originally Posted by ahamed101
this one?
Code:
echo "ab01cde234" | sed 's/.*[a-z]\([0-9]*\)$/\1/g'

--ahamed
this expression only make this examples not global!.
for example
Code:
echo "ab01cde234AA" | sed 's/.*[a-z]\([0-9]*\)$/\1/g'
ab01cde234AA

regards
ygemici
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