- For Excel or CSV files, [csvkit](https://github.com/onyxfish/csvkit) provides `in2csv`, `csvcut`, `csvjoin`, `csvgrep`, etc.
- For Amazon S3, [`s3cmd`](https://github.com/s3tools/s3cmd) is convenient and [`s4cmd`](https://github.com/bloomreach/s4cmd) is faster. Amazon's [`aws`](https://github.com/aws/aws-cli) is essential for other AWS-related tasks.
- For Amazon S3, [`s3cmd`](https://github.com/s3tools/s3cmd) is convenient and [`s4cmd`](https://github.com/bloomreach/s4cmd) is faster. Amazon's [`aws`](https://github.com/aws/aws-cli) and the improved [`saws`](https://github.com/donnemartin/saws) are essential for other AWS-related tasks.
- Know about `sort` and `uniq`, including uniq's `-u` and `-d` options -- see one-liners below. See also `comm`.