How would i put line breaks in between lines like this:
print "Hi"
print "Hi"
Because it would just output this:
HiHi
Use puts since it will automatically add a newline for you:
puts "Hi"
puts "Hi"
If you want to make an explicit newline character then you'll need to know what kind of system(s) on which your program will run:
print "Hi\n" # For UNIX-like systems including Mac OS X.
print "Hi\r\n" # For Windows.
Use line break character:
print "Hi\n"
print "Hi"
puts "\n" works also on Win/Ruby ruby 2.4.2p198
and even "\n"*4 for multiplication of new rows (by 4)
You can create a space by adding a string with only a space in it between the 2 other strings. For example:
print "Hi" + " " + "Hi"
You could avoid the two print statements and instead only use one line.
print "Hi\r\nHi"
Or if you want to use two lines then
print "Hi\r\n"
print "Hi"
Related
Im triying to use this code but not work
ruby -a -F';' -ne if $F[2]<4 'puts $F[3]' ppp.txt
this is my file
mmm;2;nsfnjd
sadjjasjnsd;6;gdhjsd
gsduhdssdj;3;gsdhjhjsd
what is doing worng Please help me
First of all, instead of treating Ruby like some kind of fancy Perl and writing scripts like that, let's expand it into the Ruby code equivalent for clarity:
$; = ';'
while gets
$F = $_.split
if $F[2]<4
puts $F[3]
end
end
Your original code doesn't work, it can't possibly work because it's not valid Ruby code, and further, you're not properly quoting it to pass through the -e evaluation term. Trying to run it I get:
-bash: 4: No such file or directory
You're also presuming the array is 1-indexed, but it's not. It's 0-indexed. Additionally Ruby treats integer values as completely different from strings, never equivalent, not auto-converted. As such you need to call .to_i to convert.
Here's a re-written program that does the job:
File.open(ARGV[0]) do |fi|
fi.readlines.each do |line|
parts = line.chomp.split(';')
if parts[1].to_i < 4
puts parts[2]
end
end
end
I solved with this
ruby -a -F';' -ne ' if $F[1] < "4" ;puts $F[2] end ' ppp.txt
I have a following file:
old_file
new_file
Some string.
end
Text in the middle that is not supposed to go to any of files.
new_file
Another text.
end
How using regex can I create two files with the following content:
file1
new_file
Some string.
end
file2
new_file
Another text.
end
How can I get information which is between keywords 'new_file' and 'end' to write it to the file?
If your files are not that large, you can read them in as a string, (use File.read(file_name)), and then run the following regex:
file_contents.scan(/^new_file$.*?^end$/m).select { |block| WRITE_TO_FILE_CODE_HERE }
See the regex demo
The ^new_file$.*?^end$ regex matches new_file that is a whole line content, then 0+ any characters as few as possible (incl. a newline as /m modifier is used), and then end (a whole line).
Else, you may adapt this answer here as
printing = false
File.open(my_file).each_line do |line|
printing = true if line =~ /^new_file$/
puts line if printing
printing = false if line =~ /^end$/
end
Open the file when the starting line is found, write to it where puts line is in the example above, and close when printing false occurs.
You can also read the file chunk by chunk by changing what constitutes a "line" in ruby:
File.open("file1.txt", "w") do |file1|
File.open("file2.txt", "w") do |file2|
enum = IO.foreach("old_file.txt", sep="\n\n")
file1.puts enum.next.strip
enum.next #discard
file2.puts enum.next.strip
end #automatically closes file2
end #automatically closes file1
By designating the separator as "\n\n" ruby will read all the characters up to and including two consecutive newlines--and return that as a "line".
If that kind of format is fixed, then you may try this (new_file\n.*\nend)
I have a file "Foo.md", which contains three lines:
Foo
Bar
I want File.read("Foo.md") to return "Foo\n\nBar" It does this when I run it from irb in the Terminal, but when I run it from a script such as
content = File.read('Foo.md')
puts content
it returns with the lines converted to actual returns. I need that variable as a single line for what comes next in my script.
To be clear: I'm not interested in changing the number of lines, just debugging to make sure the variable content is being passed as a single line.
You are still reading "Foo\n\n\nBar". However, puts interprets the special characters.
You can use String#inspect:
puts content.inspect # => "Foo\n\n\nBar"
str =
"Foo
Bar"
#=> "Foo\n\n\nBar"
You could also do this:
str.gsub(/\n{3,}/,"\n\n")
#=> "Foo\\nnBar"
It might help you visualize what is happening by meditating on this:
str = <<EOT
Foo
Bar
EOT
str's contents look like:
str # => "Foo\n\n\nBar\n"
Inspecting it escapes the backslashes for a visual representation, but it's NOT what you'd want to use when creating a string with embedded line-ends. You'd want to define it as it's shown above.
str.inspect # => "\"Foo\\n\\n\\nBar\\n\""
inspect output varies when viewed in IRB vs. the console. Here's what you'd see in the console:
ruby -e 'puts "\n"; puts "\n".inspect'
"\n"
Printing str to the console:
puts str
# >> Foo
# >>
# >>
# >> Bar
Updated description to be clearer.
Say I have a file and it has these lines in it.
one
two
three
five
How do I add a line that says "four" after the line that says "three" so my file now looks like this?
one
two
three
four
five
Assuming you want to do this with the FileEdit class.
Chef::Util::FileEdit.new('/path/to/file').insert_line_after_match(/three/, 'four')
Here is the example ruby block for inserting 2 new line after match:
ruby_block "insert_lines" do
block do
file = Chef::Util::FileEdit.new("/path/of/file")
file.insert_line_after_match("three", "four")
file.insert_line_after_match("four", "five")
file.write_file
end
end
insert_line_after_match searches for the regex/string and it will insert the value in after the match.
The following Ruby script should do what you want quite nicely:
# insert_line.rb
# run with command "ruby insert_line.rb myinputfile.txt", where you
# replace "myinputfile.txt" with the actual name of your input file
$-i = ".orig"
ARGF.each do |line|
puts line
puts "four" if line =~ /^three$/
end
The $-i = ".orig" line makes the script appear to edit the named input file in-place and make a backup copy with ".orig" appended to the name. In reality it reads from the specified file and writes output to a temp file, and on success renames both the original input file (to have the specified suffix) and the temp file (to have the original name).
This particular implementation writes "four" after finding the "three" line, but it would be trivial to alter the pattern being matched, make it count-based, or have it write before some identified line rather than after.
This is an in memory solution. It looks for complete lines rather than doing a string regex search...
def add_after_line_in_memory path, findline, newline
lines = File.readlines(path)
if i = lines.index(findline.to_s+$/)
lines.insert(i+1, newline.to_s+$/)
File.open(path, 'wb') { |file| file.write(lines.join) }
end
end
add_after_line_in_memory 'onetwothreefive.txt', 'three', 'four'
An AWK Solution
While you could do this in Ruby, it's actually trivial to do this in AWK. For example:
# Use the line number to choose the insertion point.
$ awk 'NR == 4 {print "four"}; {print}' lines
one
two
three
four
five
# Use a regex to prepend your string to the matched line.
$ awk '/five/ {print "four"}; {print}' lines
one
two
three
four
five
I have a script written in ruby. I need to remove any duplicate newlines (e.g.)
\n
\n
\n
to
\n
My current attempt worked (or rather not) using
str.gsub!(/\n\n/, "\n")
Which gave me no change to the output. What am I doing wrong?
This works for me:
#!/usr/bin/ruby
$s = "foo\n\n\nbar\nbaz\n\n\nquux";
puts $s
$s.gsub!(/[\n]+/, "\n");
puts $s
Use the more idiomatic String#squeeze instead of gsub.
str = "a\n\n\nb\n\n\n\n\n\nc"
str.squeeze("\n") # => "a\nb\nc"
You need to match more than one newline up to an infinite amount. Your code example will work with just a minor tweak:
str.gsub!(/\n+/, "\n")
For example:
str = "this\n\n\nis\n\n\n\n\na\ntest"
str.gsub!(/\n+/, "\n") # => "this\nis\na\ntest"
are you sure it shouldn't be /\n\n\n/, "\n" that what you seem to be wanting in your question above.
also, are you sure it's not doing a windows new-line "\r\n"?
EDIT: Additional info
Per Comment
"The amount of newlines can change. Different lines have between 2 and 5 newlines."
if you only want to hit the 2-5 lines try this
/\n{2,5}/, "\n"
Simply splitting and recombining the lines will give the desired result
>> "one\ntwo\n\nthree\n".split.join("\n")
=> "one\ntwo\nthree"
Edit: I just noticed this will replace ALL whitespace substrings with newlines, e.g.
>> "one two three\n".split.join("\n")
=> "one\ntwo\nthree"
First check that this is what you want!
Simply calling split will also trim out all of your whitespace.
You need to pass \n to split
>> "one ok \ntwo\n\nthree\n".split(/\n+/).join("\n")
=> "one ok \ntwo\nthree"
Additionally, also works with
spaces on blank lines
n number of back to back blank lines
str.gsub! /\n^\s*\n/, "\n\n"
where,
\n is of course newline
\s is space
denotes 1 or more spaces along when used after \s
Try This It Worked for me:
s = test\n\n\nbar\n\n\nfooo
s.gsub("\n\n", '')
Ruby needs the backslashes escaped differently than you have provided.
str.sub!("\\\\n+\\\\n","\\\\n")
http://www.ruby-forum.com/topic/176239