Download file from Amazon S3 without ruby-sdk

Today my project requirement is to download big file from Amazone S3 bucket. I am using the ruby gem (aws-sdk). This gem provide the read method for S3 object. The disadvantage of this method is it loads the entire file in memory, and you will run short of memory. My project deals in big files so this solution doesn't works for me.

After some google i found that Amazone also provide command line utility s3cmd for s3. You can setup your IAM user account by

s3cmd --configure

It will setup Amazon S3


For s3cmd options type

s3cmd --help

Make bucket
      s3cmd mb s3://BUCKET
  Remove bucket
      s3cmd rb s3://BUCKET
  List objects or buckets
      s3cmd ls [s3://BUCKET[/PREFIX]]
  List all object in all buckets
      s3cmd la
  Put file into bucket
      s3cmd put FILE [FILE...] s3://BUCKET[/PREFIX]
  Get file from bucket
      s3cmd get s3://BUCKET/OBJECT LOCAL_FILE
  Delete file from bucket
      s3cmd del s3://BUCKET/OBJECT
  Synchronize a directory tree to S3
      s3cmd sync LOCAL_DIR s3://BUCKET[/PREFIX] or s3://BUCKET[/PREFIX] LOCAL_DIR
  Disk usage by buckets
      s3cmd du [s3://BUCKET[/PREFIX]]
  Get various information about Buckets or Files
      s3cmd info s3://BUCKET[/OBJECT]
  Copy object
      s3cmd cp s3://BUCKET1/OBJECT1 s3://BUCKET2[/OBJECT2]
  Move object
      s3cmd mv s3://BUCKET1/OBJECT1 s3://BUCKET2[/OBJECT2]
  Modify Access control list for Bucket or Files
      s3cmd setacl s3://BUCKET[/OBJECT]
  Enable/disable bucket access logging
      s3cmd accesslog s3://BUCKET
  Sign arbitrary string using the secret key
      s3cmd sign STRING-TO-SIGN
  Fix invalid file names in a bucket
      s3cmd fixbucket s3://BUCKET[/PREFIX]
  Create Website from bucket
      s3cmd ws-create s3://BUCKET
  Delete Website
      s3cmd ws-delete s3://BUCKET
  Info about Website
      s3cmd ws-info s3://BUCKET
  List CloudFront distribution points
      s3cmd cflist
  Display CloudFront distribution point parameters
      s3cmd cfinfo [cf://DIST_ID]
  Create CloudFront distribution point
      s3cmd cfcreate s3://BUCKET
  Delete CloudFront distribution point
      s3cmd cfdelete cf://DIST_ID
  Change CloudFront distribution point parameters
      s3cmd cfmodify cf://DIST_ID
  Display CloudFront invalidation request(s) status
      s3cmd cfinvalinfo cf://DIST_ID[/INVAL_ID]