Read from console while piping commands in Go

Question

I need a way to read input from console twice (1 -from cat outupt, 2 - user inputs password), like this: cat ./test_data/test.txt | app account import

My current code skips password input:

reader := bufio.NewReader(os.Stdin)
raw, err := ioutil.ReadAll(reader)
if err != nil {
    return cli.NewExitError(err.Error(), 1)
}

wlt, err := wallet.Deserialize(string(raw))
if err != nil {
    return cli.NewExitError(err.Error(), 1)
}

fmt.Print("Enter password: ")
pass := ""
fmt.Fscanln(reader, &pass)

Also tried to read password with Scanln - doesn't works.

Note: cat (and piping at all) can't be used with user input, as shell redirects inputs totally. So the most simple solutions are:

to pass filename as argument
redirect manually app account import < ./test.txt

wasmup · Accepted Answer · 2017-10-23 08:01:23Z

1

Read file and password separately (and don't show password), try this:

package main

import (
    "fmt"
    "io/ioutil"
    "log"

    "github.com/howeyc/gopass"
)

func main() {
    b, err := ioutil.ReadFile("./test_data/test.txt") // just pass the file name
    if err != nil {
        fmt.Print(err)
    }
    fmt.Println(string(b))

    fmt.Print("Password: ")
    pass, err := gopass.GetPasswd()
    if err != nil {
        log.Fatalln(err)
    }
    fmt.Println(string(pass))
}

and go get github.com/howeyc/gopass first.

answered Oct 23, 2017 at 8:01

wasmup

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4 Comments

Constantine Over a year ago

Yeap, I already used terminal.ReadPassword(0) to hide password. But I need option to use my app in a shell pipeline

wasmup Over a year ago

OK so you need to read from std in , then how do you separate file data from password? it is one input stream, isn't it? when reading from one stream you need to detect fist data end and second data start, meaning sync header. may be you write a second program like cat which reads from one file and ask password from std in then send output to std out using formatted frame and sync. I hope this helps.

Xavier Nicollet Over a year ago

If you're reading the password from the terminal, it looks like everything is working. Do you still have a problem?

Constantine Over a year ago

I forget that while piping, there is no way to interrupt stdin to input password from keyboard. So maybe the option for is just to use filename

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