Question

I am new to programming please help me.
I need to read a file from particular line based on the time and write the same into another file. But its skipping the first line while writing into the other file.

timeStr="2011-08-01 02:24"
File.open(path+ "\\logs\\messages.log", "r") do |f| 
  # Skip the garbage before pattern: 
  while f.gets !~ (/#{timeStr}/) do; end                   
  # Read your data: 
  while l = f.readlines
    File.open(path+ "\\logs\\messages1.log","a") do |file1|
      file1.puts(l)
    end
  end 
end

When am running the above script the first line matching timeStr is skipped and from the second line the file is written in to the messages1. when I open messages1.log file the first line containing the matching string will not be present. Any idea how to include the first line also while writing to the messages1.log file.

Answer 1

I think you want to keep the line that matches /#{timeStr}/ but this loop:

while f.gets !~ (/#{timeStr}/) do; end

throws it away. You could rearrange things a bit:

# Get `line` in the right scope.
line = nil

# Eat up `f` until we find the line we're looking for
# but keep track of `line` for use below.
while(line = f.gets)
    break if(line =~ /#{timeStr}/)
end

# If we found the line we're looking for then get to work...
if(line)
    # Grab the rest of the file
    the_rest = f.readlines
    # Prepend the matching line to the rest of the file
    the_rest.unshift(line)
    # And write it out.
    File.open(path + "\\logs\\messages1.log","a") do |file1|
        file1.puts(the_rest)
    end
end

I haven’t tested this but it should work baring typos and the like.