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Sed grep the first matched lines

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# 1  
Old 07-13-2009
Sed grep the first matched lines
Hi

I have a myfile.txt contains the following:

Code:
CONTEXT {
  AAAAA
}
...
CONTEXT {
  BBBBB
}

I want to extract the lines in between CONTEXT { ... }, one by one.
Hence I wrote a command like the following,

Code:
sed -n '/^CONTENT/,/^}/ {
w a.txt
}' myfile.txt

The problem with this command is it will extract all the CONTEXT { ... } and write to a.txt.

How can I write only the first matched lines, e.g. CONTEXT {
AAAAA
} ???
# 2  
Old 07-13-2009
yep - sed is greedy :-)

try:

Code:
#  sed -n '/^CONTEXT/,/^}/ {p;/^}/q;}' infile
CONTEXT {
  AAAAA
}

Or in your case, to write to file:

#  sed -n '/^CONTEXT/,/^\}/ {
w a.txt
/^}/q; }' infile

HTH
Last edited by Tytalus; 07-13-2009 at 07:12 AM.. Reason: orig put in just to print - added write to file as per posters question
# 3  
Old 07-13-2009
Hi Tytalus

Your command works perfectly, but I'm trying to understand how your pattern "/^}/q;" works, could you explain or point me to the some other resource?
# 4  
Old 07-13-2009
Code:
/^}/  # match any  line beginning with }

q       #  quit

i.e. , as this gets parsed in the main section, it will print each line, until it hits this} at the start, and then it will bomb itself out.

I tend to use this style quite a lot...e.g. sed 9q infile will act just like head -9 infile, but saves you a character when typing ;-)

HTH
# 5  
Old 07-13-2009
Trying to follow your idea, but this time is to delete the first matched block with the following command:
Code:
sed '/^CONTEXT/,/^}/ {d;/^}/q;}' c.txt

Unfortunately, this command does not quite when the next } matched and it deleted all the blocks ...


What did I miss here?
# 6  
Old 07-13-2009
ah - here it did delete the fist block.

output :

Code:
#  sed '/^CONTEXT/,/^}/ {d;/^}/q;}' infile
...

But...the problem is that as it quits when it gets to the ^} line, the rest of the file doesn't get parsed at all....
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