Sed question

David T. Coffield

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Dec 12, 1986, 9:26:33 AM12/12/86

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In "sed" how can does one form a command to do the following:

Take file A, find the first line beginning with a 150,
append a line of text at that point and then write out
file A (all of it) with the newly inserted line.

Thanks for any help.

(Apologies if this seems a dumb question, but it's Friday afternoon
and I'm fed up with the manual pages...)

John Cornelius

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Dec 17, 1986, 10:27:36 PM12/17/86

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In article <1...@dcl-csvax.comp.lancs.ac.uk> da...@comp.lancs.ac.uk (David T. Coffield) writes:
>In "sed" how can does one form a command to do the following:
>
>Take file A, find the first line beginning with a 150,
>append a line of text at that point and then write out
>file A (all of it) with the newly inserted line.
>

I suppose you could try

/^150/a\
<THE LINE YOU WANT TO INSERT>

--
John Cornelius
(...!sdcsvax!piaget!jc)

Anders Weinstein

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Dec 18, 1986, 4:06:09 PM12/18/86

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In article <1...@dcl-csvax.comp.lancs.ac.uk> da...@comp.lancs.ac.uk (David T. Coffield) writes:

>In "sed" how can does one form a command to do the following:
>
>Take file A, find the first line beginning with a 150,
>append a line of text at that point and then write out
>file A (all of it) with the newly inserted line.

If the pattern /^150/ is only going to occur once in the input, then it's
easy:

/^150/a\
line-of-text-to-append-here

Otherwise, you could try using two loops in the script as follows:

:loop1
/^150/{
a\
line-of-text-to-append-here
b loop2
}
n
b loop1
:loop2
n
b loop2

--
Anders Weinstein <awei...@DIAMOND.BBN.COM>

Kent Black

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Dec 31, 1986, 1:37:13 PM12/31/86

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In article <1...@piaget.UUCP> j...@piaget.UUCP (John Cornelius, System Manager) writes:
>In article <1...@dcl-csvax.comp.lancs.ac.uk> da...@comp.lancs.ac.uk (David T. Coffield) writes:
>>In "sed" how can does one form a command to do the following:
>>
>>Take file A, find the first line beginning with a 150,

^^^^^

>>append a line of text at that point and then write out
>>
>

>/^150/a\
><THE LINE YOU WANT TO INSERT>
>
>--
>John Cornelius
>(...!sdcsvax!piaget!jc)

This will append the text after every line beginning with '150'.

I cannot find a brilliant, elegant solution (but then, I'm neither
brilliant nor elegant), but I found a nice crufty one:
(don't even attempt this in csh! ;-)
$ sed -n '/^150/ {
> =
> q
> } ' filename
will write the number of the first line on which /^150/ occurs. You
can try to work out the substitution of one sed as input for another;
I settled for:
$ line=`sed -n '/^150/ {
> ... filename`
$ sed ''$line' a\
> new text, remember\
> to escape newlines
> ' filename

The two single quotes before $line are necessary.

Hope someone does better; unless you have an overwhelming need for sed,
this is easier in awk.

-- kab

Chris Torek

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Jan 1, 1987, 8:32:42 AM1/1/87

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I must have missed the original article, but the goal appears to
be to get `sed' to add a line of text after the first occurrence
of some particular pattern (here `^150'), but only the very first.
It is not difficult:

% cat foo.sed
:notyet
/^150/{a\
some\
new\
text
b copy
}
n
b notyet
:copy
n
b copy
% sed -f foo.sed
...
--
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690)
UUCP: seismo!mimsy!chris ARPA/CSNet: ch...@mimsy.umd.edu