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Old 05-19-2006
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question on egrep

Hi
I am trying to use this command:
egrep '^a{2,6}$' testexpr4D

to retreive lines with 2,3,4,5, or 6 a's in a file .
The file testexpr4D has entries like:
a
aa
aaa
aaaa
aaaaa
aaaaaa
123456
ABCDEF

I was expecting to see 5 lines in the output but nothing happens.
Can anyone help please?
Thanks
Rohit
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Old 05-19-2006
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Code:
egrep '^a\{2,6\}$' testexpr4D
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Old 05-19-2006
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question on egrep

Hi Shreenmotor,
That doesn't work either !

Thanks
Rohit
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Old 05-19-2006
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This works:
Code:
 egrep '^(a)(a)?' filename
test:
Code:
kcsdev:/home/jmcnama> cat filename
a
aa
aaa
aaaa
aaaaa
aaaaaa
123456
ABCDEF



kcsdev:/home/jmcnama> egrep '^(a)(a)?' filename
a
aa
aaa
aaaa
aaaaa
aaaaaa
Note:
Code:
 egrep '^(a)+$' filename
is closer to correct - correct being 'find a line of any non-zero length that has only the letter a'

Last edited by jim mcnamara; 05-19-2006 at 12:36 PM.
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Old 05-22-2006
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question on egrep

Jim,
Your solution fetches all the a's in a file . I need to fetch the lines with
2 to 6 a's in a line
Rohit
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Old 05-22-2006
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Quote:
Originally Posted by shereenmotor
Code:
egrep '^a\{2,6\}$' testexpr4D
shereenmotor, that solution is pretty close, but no cigar !

You are mixing the syntax's of sed and [e]grep.

If it were sed, it would be

Code:
sed -n -e "/^a\{2,6\}$/p" filename
If it were grep it would be

Code:
egrep '^a{2,6}$' filename
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Old 05-22-2006
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put one 'a'

Put a single a before the mentioned pattern. You should get your result.
egrep '^a(a)+$' filename
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Old 05-22-2006
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For egrep the limit on the number of allowed matches is expressed {lower,upper}

Code:
egrep '^a{1,6}$'
finds a line made only of one to six characters 'a' -s
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Old 05-23-2006
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question on egrep

Hi Ranj,
Your solution works for
egrep '^a(a)+$'

But can you tell me how to interpret this please?

How does this know it needs to select 2.. upto 6 a's ?

Thanks
Rohit
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Old 05-23-2006
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It doesn't limit the search to a maximum of 6 a's.
Example test with seven a's:
Code:
/home/jmcnama > echo "aaaaaaa" | egrep '^a(a)+$'
aaaaaaa
try it.
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Old 05-25-2006
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question on egrep

Hi Jim,
Thanks for your response but my requirement was really limiting the selection between 2 and 6 a's. (or for that matter a user specified number).
Any clues ?

Rohit
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