BASH: is it possible to use "\n" in a search command?

carolflb · 11-18-2009, 10:01 AM

Hi all,

I need to find a way to insert a string in a text after a pattern. The problem is that the pattern can not be found in one line, so I would need to tell the command in bash that the second part of the pattern comes in the next line after the first part of the pattern was found. So I tried:

sed -i '/[^ ]*<nta>'\n'<declaration>[^ ]*/ a\string' file.txt

But sadly the sed command like this can't find in the text what I want him to find...

Here is the text (the pattern I'm looking for is highlighted):

<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE nta (View Source for full doctype...)>
<nta>
<declaration>// 971204, Arne, Fredrik, Kim & Paul. // Fairmont Hotel, San Francisco.</declaration>
<template>
<name x="32" y="16">Door</name>

Does somebody knows a solution for this?

ghostdog74 · 11-18-2009, 10:22 AM

gawk

Code:

gawk -vRS="<declaration>" -vFS="\n" ' # set record separator as "<declaration>", field separator as "\n"
$(NF-1) == "<nta>"{ f=1 }   # if last 2nd field is <nta> , toggle flag
f { 
  # print the string for toggled flag
  printf $0 RT "string"
  f=0 # reset flag
  next
}f==0' file

output

Code:

# ./shell.sh
<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE nta (View Source for full doctype...)>
<nta>
<declaration>string// 971204, Arne, Fredrik, Kim & Paul. // Fairmont Hotel, San Francisco.</declaration>
<template>
<name x="32" y="16">Door</name>

carolflb · 11-18-2009, 10:35 AM

Thanks for another solution Ghostdog!

This time it also works, but I didn't get how the code works, could you explain it a little?

carolflb · 11-18-2009, 11:04 AM

Hey Ghostdog, yesterday you also replied to another thread I posted:

http://www.linuxquestions.org/questi...w-file-769456/

But sadly I didn't get the answer I wanted...I think I didn't write my question the right way. Would you take a look at the thread again? I made a comment there. I need a command that searches a pattern in a text file, but that just substitutes the first occurency of it and not all of them.