Pipelines

You can run this markdown file:
zx docs/pipelines.md

The zx supports Node.js streams and special pipe() method can be used to redirect stdout.

await $`echo "Hello, stdout!"`
  .pipe(fs.createWriteStream('/tmp/output.txt'))

await $`cat /tmp/output.txt`

Processes created with $ gets stdin from process.stdin, but we can also write to child process too:

let p = $`read var; echo "$var";`
p.stdin.write('Hello, stdin!\n')

let {stdout} = await p

Pipes can be used to show real-time output of programs:

$.verbose = false

await $`echo 1; sleep 1; echo 2; sleep 1; echo 3;`
  .pipe(process.stdout)

Pipe both stdout and stderr:

let echo = $`echo stdout; echo stderr 1>&2`
echo.stdout.pipe(process.stdout)
echo.stderr.pipe(process.stdout)
await echo

Also, the pipe() method can combine $ programs. Same as | in bash:

let greeting = await $`printf "hello"`
  .pipe($`awk '{printf $1", world!"}'`)
  .pipe($`tr '[a-z]' '[A-Z]'`)

console.log(greeting.stdout)

Use combinations of pipe() and nothrow():

await $`find ./examples -type f -print0`
  .pipe(nothrow($`xargs -0 grep ${'missing' + 'part'}`))
  .pipe($`wc -l`)

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