Deno ShellStream

ShellStream is a lib for Deno that mix I/O stream API and Shell pipe/redirects.

It has zero 3rd party dependencies and don't internally run sh or bash commands.

Quick exemples

import {
  FromFile,
  FromRun,
} from "https://deno.land/x/shell_stream@v0.1.5/mod.ts";
import { bgBlue } from "https://deno.land/std@0.112.0/fmt/colors.ts";

let res = await FromRun("cat /etc/passwd").run("grep /root").toString();
console.log(res); // → root❌0:0:root:/root:/bin/bash

// the same example without run cat & grep command :
res = await FromFile("/etc/passwd")
  .log(bgBlue) // → log the entire file with blue background
  .grep(/\/root/) // keep lines that contain /root
  .log() // → log "root❌0:0:root:/root:/bin/bash"
  .toString();
console.log(res); // → res = "root❌0:0:root:/root:/bin/bash"

res = await FromRun("deno --version").head(1).toString();
console.log(res); // → deno 1.15.1 (release, x86_64-unknown-linux-gnu)

console.log(await FromRun(["deno", "--version"]).tail(2).toArray());
// → ["v8 9.5.172.19", "typescript 4.4.2"]

// exit codes of processes can be retrieved :
const closeRes = await FromRun([
  Deno.execPath(),
  "eval",
  'console.log("foo"); Deno.exit(13)',
])
  .run("cat")
  .run("cat")
  .close();
const exitCodes = closeRes.statuses.map((s) => s?.code);
console.log(
  `success=${closeRes.success} codes=${exitCodes} out=${closeRes.out}`,
);
// → "success=false codes=13,0,0 out=foo"

See more examples in example.ts file.

Operators

The usage : res = await Startpoint(...).Operator(...).Operator(...).Endpoint(...)

All startpoints and operators return a ShellStream, the endpoints return a promise. ShellStream contains all operators as method, the IDEs can autocomplete/check the code.

Startpoint Operators

These operators return a ShellStream :

• FromRun(cmd: string[] | string, opt?: RunOptions ) → generate a stream with each line of the stdout of the process. If cmd is a string, it will be parsed to array.
• FromFile(path: string) → generate a stream with each line of the file.
• FromArray(lines: string[]) → generate a stream with each element of the array.
• Pipe: see bellow "Pipe chapter"

The startpoint are also available from static method of ShellStream :

ShellStream.fromRun(cmd: string[] | string, opt?: RunOptions);
ShellStream.fromFile(path: string);
ShellStream.fromArray(lines: string[]);
ShellStream.pipe(...operators: OperatorFunc[]);

Intermediate Operators

These operators return a ShellStream :

• run(cmd: string[] | string, opt?: RunOptions ) : generate a stream with each line of the stdout of the process. The current stream is passed to the stdin of the process. If cmd is a string, it will be parsed to array (regex used to split : /"(\\"|[^"])*"|'(\\'|[^'])*'|[^ "']*/g).
• tap(tapFunction: TapFunction) : keep stream unchanged, run the tapFunction with the current line as argument.
• tee(outputPath: string) : keep stream unchanged, write the stream in the outputPath file.
• log(transform?: LogTransformFunction) : keep stream unchanged, log each lines in console.
• logWithTimestamp : keep stream unchanged, log each lines in console with the date (ISOString) at the beginning.
• map(mapFunction: MapFunction) : transform the stream with the return of mapFunction, the current line is passed as the first argument to the mapFunction.
• timestamp() : transform the stream with the date (ISOString) at the begining.
• replace(v: string | RegExp, r: Replacer) : transform the stream with the replace result.
• cut(delim: string, indexes: number[], sep = " ") : transform the stream with the part ordered by indexes, split the line by sep.
• filter(filterFunction: FilterFunction) : transform the stream, keep only lines that return true in filterFunction.
• grep(regex: RegExp) : transform the stream, keep only lines that match the regex.
• head(count = 1) : transform the stream, keep only first count lines.
• tail(count = 1) :transform the stream, keep only last count lines.
• pipe(...operators: OperatorFunc[]) : see bellow "Pipe chapter".

Endpoint Operators

All these operators close the stream and return a Promise :

• toString():Promise<string> : the stream is closed and converted to String.
• toArray():Promise<string[]> : the stream is closed and converted to Array.
• toFile(outputPath: string):Promise<CloseRes> : the stream is closed and write to the converted file.
• close(opt?: CloseOptions = { processes: "AWAIT" }):Promise<CloseRes> : close all ressources and wait end of operators (includes processes end)
• success():Promise<boolean> : the stream is closed and CloseRes.success is returned

export type CloseRes = {
  success: boolean;
  statuses: ((Deno.ProcessStatus & { cmd: string[] }) | undefined)[];
  out: string[];
};

• success : true if all processes run from the startpoint are in success status
• statuses: array of status of all operators from startpoint
• out: array of the output stream

RunOptions

Extends Deno.RunOptions

export type RunOptions = Omit<Deno.RunOptions, "cmd"> & {
  throwIfRunFail?: boolean;
  exitCodeIfRunFail?: number;
  streamStdErr?: boolean;
};

• throwIfRunFail: if the process exit code !== 0, throw error
• exitCodeIfRunFail: if the process exit code !== 0, immediately exit from Deno
• streamStdErr: stream stderr of the process instead of the stdout
• stdout: Deno.run option, unused if streamStdErr !== true
• stderr: Deno.run option, unused if streamStdErr === true

Pipe

Pipe(...operators: OperatorFunc[])

An alternative "pipe" API is possible. The "call chain" version :

await FromArray(["1", "2", "3"])
  .filter((l) => parseInt(l) > 1) // keep ["2", "3"]
  .run("wc -l") // "wc -l" count input lines
  .log() // log "2"
  .close();

The "pipe" API version :

await Pipe(
  fromArray(["1", "2", "3"]),
  filter((l: string) => parseInt(l) > 1), // keep ["2", "3"],
  run("wc -l"), // "wc -l" count input lines
  log(), // log "2"
).close();

Pipe is also available from ShellStream Class :

await FromArray(["1", "2", "3"])
  .filter((l) => parseInt(l) > 1) // keep ["2", "3"]
  .pipe(
    run("wc -l"), // "wc -l" count input lines
    log(), // log "2"
  )
  .close();

Deno API only equivalents

await FromRun("cat /etc/passwd").grep(/\/root/).toString();

is equivalent to :

const process = Deno.run({
  cmd: ["cat", "/etc/passwd"],
  stdout: "piped",
});
res = new TextDecoder()
  .decode(await process.output())
  .split("\n")
  .filter((line) => line.match(/\/root/))
  .join("\n");
process.close();
console.log(res); // → root❌0:0:root:/root:/bin/bash

await FromRun("cat /etc/passwd").run("grep /root").toString();

is equivalent to :

const process1 = Deno.run({ cmd: ["cat", "/etc/passwd"], stdout: "piped" });
const process2 = Deno.run({
  cmd: ["grep", "/root"],
  stdin: "piped",
  stdout: "piped",
});
// copy() get stuck if the process1.stdout is not closed
(async () => {
  await process1.status();
  process1.stdout!.close();
  process1.close();
})();
try {
  await copy(process1.stdout!, process2.stdin!);
} catch (_) {
  // process1.stdout.close() generate BadResource exception in copy()
}
process2.stdin!.close();
res = new TextDecoder().decode(await process2.output());
process2.close();
console.log(res); // → root❌0:0:root:/root:/bin/bash

Warning : ShellStream streams line by line, and the performances is then reduced. The behavior can probably be different from shell pipes, especially if the stream is not text.

Development

The folder .DENO_DIR and .lock.json are not necessary for the project to work, it just allows to save its dependencies.

Some dev command are listed in the scripts.yaml file, this file can be use with Velociraptor :

• test: launch tests
• test-watch: launch tests on file change
• lint: lint the code
• fmt: format the code
• bundle: bundle the project and its dependencies to dist/shell_stream.js
• bak-dep: backup the dependencies to .DENO_DIR and update .lock.json
• gen-cov: generate the test coverage

The sanitize function from sanitize.ts check if all ressource and ops are
closed/completed.