Extract lines from text file
 

Hi,

I'm looking for a command to extract lines from a large text file, a
password file. A typical user has a username made from a letter
followed by their id-number.

m9718508:pw:9301:840: Lynch :/home/pgstud/m9718508:/bin/bash

So for instance if I need to extract lines where;

the 1st field, the username begins with an m
and
the 4th field, the group contains exactly 850

cat passwdfile | grep ^m | grep 850 > output

is close but fails if the value 850 appears outside the 4th field. In
the above example which should be ignored 850 appears in the username
and home directory and is therefore extracted.

Any ideas.

Thanks,

Tony
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Extract lines from text file
 

Greetings,

On Wed, Aug 15, 2012 at 7:52 PM, Tony Molloy <tony.molloy@ul.ie> wrote:
>
> Hi,
>
>
> So for instance if I need to extract lines where;
>
> the 1st field, the username begins with an m
> and
> the 4th field, the group contains exactly 850
>

cut -d: -f1,4 <input-filename>

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Regards,

Rajagopal
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Extract lines from text file
 

Hello Tony,


On Wed, 15 Aug 2012 15:22:10 +0100 Tony Molloy <tony.molloy@ul.ie> wrote:

>
> Hi,
>
> I'm looking for a command to extract lines from a large text file, a
> password file. A typical user has a username made from a letter
> followed by their id-number.
>
> m9718508:pw:9301:840: Lynch :/home/pgstud/m9718508:/bin/bash
>
> So for instance if I need to extract lines where;
>
> the 1st field, the username begins with an m
> and
> the 4th field, the group contains exactly 850
>
> cat passwdfile | grep ^m | grep 850 > output
>
> is close but fails if the value 850 appears outside the 4th field. In
> the above example which should be ignored 850 appears in the username
> and home directory and is therefore extracted.

Something like `grep -E '^m.+:.*:.*:850:'` maybe?


Regards,

--
wwp
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Extract lines from text file
 

Em 15-08-2012 11:22, Tony Molloy escreveu:
>
> Hi,
>
> I'm looking for a command to extract lines from a large text file, a
> password file. A typical user has a username made from a letter
> followed by their id-number.
>
> m9718508:pw:9301:840: Lynch :/home/pgstud/m9718508:/bin/bash
>
> So for instance if I need to extract lines where;
>
> the 1st field, the username begins with an m
> and
> the 4th field, the group contains exactly 850
>
> cat passwdfile | grep ^m | grep 850 > output
>
> is close but fails if the value 850 appears outside the 4th field. In
> the above example which should be ignored 850 appears in the username
> and home directory and is therefore extracted.
>
> Any ideas.


]$ cat testcentoslist
m9718508:pw:9301:840: Lynch :/home/pgstud/m9718508:/bin/bash
m9718308:pw:9301:850: Lynch :/home/pgstud/m9718508:/bin/bash
m9718208:pw:9301:840: Lynch :/home/pgstud/m9718508:/bin/bash
m9718508:pw:9301:840: Lynch :/home/pgstud/m9718908:/bin/bash

]$ cat testcentoslist | egrep ^m.*:.*:.*:850:
m9718308:pw:9301:850: Lynch :/home/pgstud/m9718508:/bin/bash



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