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Javascript Terminal String Editor: NSed brings Node.js power to the command line.

It works similarly to the standard GNU sed command, with the exception that everything is Javascript and powered by Node.js.

For instance, the following command computes the hash of each file in the test folder:

find test -type f | nsed -r crypto -c 'fs.readFileSync($data, "utf8")' -c 'crypto.createHash("md5").update($data).digest("hex")'


To install and use Nsed, Node.js 7.6 or above is needed (due to the use of async/await).

To install, simply use npm or yarn:

npm install -g nsed


Basic usage

Each command is executed on the output of the previous one. You can reference $data for the current input and $index for the current position in the input.

If operating directly on properties or methods of the input, you can omit $data.

find test -type f | nsed -r crypto -c 'fs.readFileSync($data, "utf8")' -c '.length'

Since it requires a recent Node.js implementation (7.6+), you can use advanced features like async/await.

To see all the available options, use -h|--help option.


Input lines can be filtered out by using filter (-f|--filter) or reverse filters (-F|--reverse-filter) that, respectively, will include the input if the result of the evaluation is a truthy or falsy value (according to Javascript rules).

For instance, the following command will print only files starting with index:

find test -type f | nsed -f '/^index/'

Regular expressions

Regular expression can be used in commands and referenced later, using $NUMBER syntax.

For instance, the following command will print the second letter of each file:

find test -type f | nsed -c '.replace("test/", "")' -c '/.(.).+/' -c '$1'

Advanced usage

Before processing commands, you can instruct nsed to require any available Node.js modules, by using -r|--require switch. The module will be available with its name camelcased. For instance, -r string_decoder will make stringDecoder available for your commands.

Finally, instead of providing commands via command line, you can input Javascript file using -s|--source switch. The source file must export a function which accepts a string ($data representing the current line) and a number ($index, representing the current line in the input).

Supported implementations

nsed needs, supports and has been tested on NodeJS 7.6+.

Contributing to nsed

  • Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet.
  • Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it.
  • Fork the project.
  • Start a feature/bugfix branch.
  • Commit and push until you are happy with your contribution.
  • Make sure to add tests for it. This is important so I don't break it in a future version unintentionally.


Copyright (C) 2017 and above Shogun

Licensed under the MIT license, which can be found at


Javascript Terminal String Editor



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