无法从Golang运行bash`read`命令[重复]

Question

This question already has an answer here:

• Read a character from standard input in Go (without pressing Enter) 6 answers

I tried to use a basic bash command read to capture a single character from a keyboard. But it seemed difficult to get the output even I try several ways.

Sample code:

fmt.Println(exec.Command("read", "-t", "5", "-n", "1").Output())

Its meaning is "waiting for 5 seconds to get 1 input character from the keyboard". From code above I expected to see my input character printed out together with its error but what do I get is

Output:

[] exit status 1

This output is just immediately printed in lesser than 1 second which conflicts to "-t", "5" argument of read command which stands for waiting for 5 second. I try to type some character within 1 second but it seems doesn't work at all.

BTW, if try this

fmt.Println(exec.Command("echo", "\"Hi!\"").Output())

output:

[34 104 105 34 10] <nil>

It seems work here with simple echo here.

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Answer 1

You're not providing the command with stdin, so there's nothing it can read and it exits immediately.

If you want to hook it up the same stdin as the calling program, you can use:

cmd := exec.Command("read", "-t", "5", "-n", "1")
cmd.Stdin = os.Stdin
out, err := cmd.CombinedOutput()

fmt.Println("error:", err)
fmt.Printf("output: %q
", out)

This however won't output anything, since the /usr/bin/read script isn't going to print anything. You probably want the shell builtin read to be called in the context of a shell. This would print the character read:

cmd := exec.Command("bash", "-c", "read -t 5 -n 1 C && echo -n $C")
cmd.Stdin = os.Stdin

But in the end, you should probably just read directly from stdin in go.