CODEWITHSUNDEEP
ruby
Eugene Fedotov
Eugene Fedotov

Reputation: 354

Trying to create a Ruby script. I want to append Strings containing commands to a file

mysqldump = "mysqldump"
`#{mysqldump} > backup_file.sql`

I'm supposed to append several of those mysqldump Strings (I simplified it for this example; normally line 2 would have the username and password as options) into the SQL file.

The problem is line 2, when I try to call the Bash operator '>' to append the String. Instead of appending, the script ends up calling the mysqldump command itself.

What can I do to store the String "mysqldump" into the file backup_file.sql? I want to do it the same way as line 2: automatically appending through the Bash.

Upvotes: 0

Views: 93

Answers (2)

z atef
z atef

Reputation: 7679

if you are trying to append "like" you said and not overwrite the target file use >> instead of > . Here is a working version of your script: 

za$ emacs ./foo.rb

#!/usr/bin/env ruby

target_dir = "/Users/za/ruby-practice/backup_file.sql"

mysqldump = "mysqldump"
`echo #{mysqldump} >> "#{target_dir}"`

You can also do something like : system %Q{echo "#{mysqldump}" >> "#{target_dir}"} . Personally , I would say use IO#puts instead of making system calls inside your script , if you want a pure ruby solution/system independent solution.

Upvotes: 2

sammygadd
sammygadd

Reputation: 299

Why don't you use pure ruby to do it? Like:

File.open("backup_file.sql", "w") do |f|
  dump_lines.each do |line|
    f.puts line
  end
end

assuming that you have the dump in an array..

Upvotes: 0

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