trying to reverse engineer somebodys script - what do the following lines do 
when run against an input file:

sed '1,2d'
sed '2,3d'

I can see what they are doing to the data but I just want it explained for 
my own sanity.

Thanks 

In article <i561fp$24q$1@usenet01.boi.hp.com>,
 "banzai" <banzai@aaaa.com> wrote:

> trying to reverse engineer somebodys script - what do the following lines do 
> when run against an input file:
> 
> sed '1,2d'
> sed '2,3d'
> 
> I can see what they are doing to the data but I just want it explained for 
> my own sanity.
> 
> Thanks 

The first one prints all lines of the file except the first two 
(eqivalent to "tail +3").  The second prints all lines of the file 
except lines 2-3.

What's so confusing about them?  The "d" command deletes lines, and the 
prefix is a range of line numbers.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
*** PLEASE don't copy me on replies, I'll read them in the group ***

On 8/26/2010 8:37 PM, Barry Margolin wrote:
> In article<i561fp$24q$1@usenet01.boi.hp.com>,
>   "banzai"<banzai@aaaa.com>  wrote:
>
>> trying to reverse engineer somebodys script - what do the following lines do
>> when run against an input file:
>>
>> sed '1,2d'
>> sed '2,3d'
>>
>> I can see what they are doing to the data but I just want it explained for
>> my own sanity.
>>
>> Thanks
>
> The first one prints all lines of the file except the first two
> (eqivalent to "tail +3").  The second prints all lines of the file
> except lines 2-3.

Maybe. Kinda. Depends. If what was posted represents

sed '1,2d' file
sed '2,3d' file

then it'd do what you say, but if it represents

sed '1,2d' file |
sed '2,3d'

then it'd print all but the 4th and 5th lines of the file.

	Ed.

>
> What's so confusing about them?  The "d" command deletes lines, and the
> prefix is a range of line numbers.
>

In article <i57atk$71r$1@news.eternal-september.org>,
 Ed Morton <mortonspam@gmail.com> wrote:

> On 8/26/2010 8:37 PM, Barry Margolin wrote:
> > In article<i561fp$24q$1@usenet01.boi.hp.com>,
> >   "banzai"<banzai@aaaa.com>  wrote:
> >
> >> trying to reverse engineer somebodys script - what do the following lines 
> >> do
> >> when run against an input file:
> >>
> >> sed '1,2d'
> >> sed '2,3d'
> >>
> >> I can see what they are doing to the data but I just want it explained for
> >> my own sanity.
> >>
> >> Thanks
> >
> > The first one prints all lines of the file except the first two
> > (eqivalent to "tail +3").  The second prints all lines of the file
> > except lines 2-3.
> 
> Maybe. Kinda. Depends. If what was posted represents
> 
> sed '1,2d' file
> sed '2,3d' file
> 
> then it'd do what you say, but if it represents
> 
> sed '1,2d' file |
> sed '2,3d'
> 
> then it'd print all but the 4th and 5th lines of the file.
> 

Sure, if you change the commands, they do different things.  It will 
also behave differently if you connect them with && or ||.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
*** PLEASE don't copy me on replies, I'll read them in the group ***

On 8/27/2010 10:33 PM, Barry Margolin wrote:
> In article<i57atk$71r$1@news.eternal-september.org>,
>   Ed Morton<mortonspam@gmail.com>  wrote:
>
>> On 8/26/2010 8:37 PM, Barry Margolin wrote:
>>> In article<i561fp$24q$1@usenet01.boi.hp.com>,
>>>    "banzai"<banzai@aaaa.com>   wrote:
>>>
>>>> trying to reverse engineer somebodys script - what do the following lines
>>>> do
>>>> when run against an input file:
>>>>
>>>> sed '1,2d'
>>>> sed '2,3d'
>>>>
>>>> I can see what they are doing to the data but I just want it explained for
>>>> my own sanity.
>>>>
>>>> Thanks
>>>
>>> The first one prints all lines of the file except the first two
>>> (eqivalent to "tail +3").  The second prints all lines of the file
>>> except lines 2-3.
>>
>> Maybe. Kinda. Depends. If what was posted represents
>>
>> sed '1,2d' file
>> sed '2,3d' file
>>
>> then it'd do what you say, but if it represents
>>
>> sed '1,2d' file |
>> sed '2,3d'
>>
>> then it'd print all but the 4th and 5th lines of the file.
>>
>
> Sure, if you change the commands, they do different things.  It will
> also behave differently if you connect them with&&  or ||.
>

I wasn't changing them, I was just mentioning that depending how they're used 
they could do different things. The 2 commands as written would've done nothing 
at all since they weren't operating on a file or the output of a pipe. There 
wouldn't be much point running them both back-to-back on the same file so there 
must be something more to the way they're used than that.

	Ed.

In article <i5a143$1ci$1@news.eternal-september.org>,
Ed Morton  <mortonspam@gmail.com> wrote:
....
>I wasn't changing them, I was just mentioning that depending how
>they're used they could do different things. The 2 commands as written
>would've done nothing at all since they weren't operating on a file or
>the output of a pipe. There wouldn't be much point running them both
>back-to-back on the same file so there must be something more to the
>way they're used than that.

Ah yes, the joy of reverse engineering the real problem.  Of reverse
engineering the OP's mind...

The fact is that the commands as written will most likely simply
generate an error message - so, really that's what we should be telling
OP:

 % sed 1,2d file
sed: can't read file: No such file or directory
 % 

-- 
"We should always be disposed to believe that which appears to us to be
white is really black, if the hierarchy  of the church so decides." 

    - Saint Ignatius Loyola (1491-1556) Founder of the Jesuit Order -

Sat, 28 Aug 2010 12:35:30 +0000, Kenny McCormack did cat :

> In article <i5a143$1ci$1@news.eternal-september.org>, Ed Morton 
> <mortonspam@gmail.com> wrote: ...
>>I wasn't changing them, I was just mentioning that depending how they're
>>used they could do different things. The 2 commands as written would've
>>done nothing at all since they weren't operating on a file or the output
>>of a pipe. There wouldn't be much point running them both back-to-back
>>on the same file so there must be something more to the way they're used
>>than that.
> 
> Ah yes, the joy of reverse engineering the real problem.  Of reverse
> engineering the OP's mind...
> 
> The fact is that the commands as written will most likely simply
> generate an error message - so, really that's what we should be telling
> OP:
> 
>  % sed 1,2d file
> sed: can't read file: No such file or directory
>  %

works perfectly here and then, your implementation of
reverse-humoring must be slightly b0rken ;-)
----------
$ cat > file
"We should always be disposed to believe that which appears to us to be
white is really black, if the hierarchy  of the church so decides." 

    - Saint Ignatius Loyola (1491-1556) Founder of the Jesuit Order -
$ sed 1,2d file

    - Saint Ignatius Loyola (1491-1556) Founder of the Jesuit Order -
----------

In article <pan.2010.08.28.15.26.00@thedarkdesign.free.fr.INVALID>,
Loki Harfagr  <l0k1@thedarkdesign.free.fr.INVALID> wrote:
....
>$ cat > file

???

Where did this command come from?  What makes you think you can include
that in the mix?  Certainly wasn't in the OP's post - so therefore, it
just came from the recesses of your mind.

-- 
"We should always be disposed to believe that which appears to us to be
white is really black, if the hierarchy  of the church so decides." 

    - Saint Ignatius Loyola (1491-1556) Founder of the Jesuit Order -

Sat, 28 Aug 2010 17:55:26 +0000, Kenny McCormack did cat :

> In article <pan.2010.08.28.15.26.00@thedarkdesign.free.fr.INVALID>, Loki
> Harfagr  <l0k1@thedarkdesign.free.fr.INVALID> wrote: ...
>>$ cat > file
> 
> ???
> 
> Where did this command come from?  What makes you think you can include
> that in the mix?  Certainly wasn't in the OP's post

exactly like were not most of the possible questions/answers
about why/what/how/when were the few sed verbs called :-)

> - so therefore, it
> just came from the recesses of your mind.

I see you're now on the same page hence might be you read it again ;-)

In article <pan.2010.08.28.20.57.46@thedarkdesign.free.fr.INVALID>,
Loki Harfagr  <l0k1@thedarkdesign.free.fr.INVALID> wrote:
>Sat, 28 Aug 2010 17:55:26 +0000, Kenny McCormack did cat :
>
>> In article <pan.2010.08.28.15.26.00@thedarkdesign.free.fr.INVALID>, Loki
>> Harfagr  <l0k1@thedarkdesign.free.fr.INVALID> wrote: ...
>>>$ cat > file
>> 
>> ???
>> 
>> Where did this command come from?  What makes you think you can include
>> that in the mix?  Certainly wasn't in the OP's post
>
>exactly like were not most of the possible questions/answers
>about why/what/how/when were the few sed verbs called :-)

Huh?  Maybe you meant to say:

>the the verbs like why/what/how/when most few possible called were were
>of sed exactly about questions/answers :-) not

>> - so therefore, it
>> just came from the recesses of your mind.
>
>I see you're now on the same page hence might be you read it again ;-)

And here, maybe you meant:

>;-) be same see it on might you page you're again the I read hence now

-- 
> No, I haven't, that's why I'm asking questions. If you won't help me,
> why don't you just go find your lost manhood elsewhere.

CLC in a nutshell.