How do I join two lines of a file by matching pattern, in Ruby or Bash? - ruby

Question

I'm using a Ruby script to do a lot of manipulation and cleaning to get this, and a bunch of other files, ready for import.
I have a really large file with some data that I'm trying to import into a database. There are some data issues with newline characters being in the data where they should not be, messing with the import.
I was able to solve this problem with sed using this:
sed -i '.original' -e ':a' -e 'N' -e '$!ba' -e 's/Oversight Bd\n/Oversight Bd/g' -e 's/Sciences\n/Sciences/g' combined_old_individual.txt"
However, I can't call that command from inside a Ruby script, because Ruby messes up interpreting the newline characters and won't run that command. sed needs the non-escaped newline character but when calling a system command from Ruby it needs a string, where the newline character needs to be escaped.
I also tried doing this using Ruby's file method, but it's not working either:
File.open("combined_old_individual.txt", "r") do |f|
File.open("combined_old_individual_new.txt","w") do |new_file|
to_combine = nil
f.each_line do |line|
if(/Oversight Bd$/ =~ line || /Sciences$/ =~ line)
to_combine = line
else
if to_combine.nil?
new_file.puts line
else
combined_line = to_combine + line
new_file.puts combined_line
to_combine = nil
end
end
end
end
end
Any ideas how I can join lines where the first line ends with "Bd" or "Sciences", from within a Ruby script, would be very helpful.
Here's an example of what might go in a testfile.txt:
random line
Oversight Bd
should be on the same line as the above, but isn't
last line
and the result should be
random line
Oversight Bdshould be on the same line as the above, but isn't
last line

Answer 1

With ruby (My first attempt at a ruby answer):
File.open("combined_old_individual.txt", "r") do |f|
File.open("combined_old_individual_new.txt","w") do |new_file|
f.each_line do |line|
if(/(Oversight Bd|Sciences)$/ =~ line)
new_file.print line.strip
else
new_file.puts line
end
end
end
end

Answer 2

You have to realize that sed normally works line by line, so you cannot match for \n in your initial pattern. You can however match for the pattern on the first line and then pull in the next line with the N command and then run the substitute command on the buffer to remove the newline like so:
sed -i -e '/Oversight Bd/ {;N;s/\n//;}' /your/file
Run from Ruby (without -i so that the output goes to stdout):
> cat test_text
aaa
bbb
ccc
aaa
bbb
ccc
> cat test.rb
cmd="sed -e '/aaa/ {;N;s/\\n//;}' test_text"
system(cmd)
> ruby test.rb
aaabbb
ccc
aaabbb
ccc

Answer 3

Since you are asking in bash, here is a pure-bash solution:
$ r="(Oversight Bd|Sciences)$"
$ while read -r; do printf "%s" "$REPLY"; [[ $REPLY =~ $r ]] || echo; done < combined_old_individual.txt
random line
Oversight Bdshould be on the same line as the above, but isn't
last line
$