How Can I Detect if Go's STDIN Input is from a Pipe or a Terminal?

Detecting STDIN Data Availability in Go

In your code, you aim to distinguish between when data is piped into STDIN and when it is executed from a terminal. The challenge lies in addressing the blocking nature of ioutil.ReadAll(), which waits indefinitely for input when STDIN is empty.

Solution: Using os.ModeCharDevice

To resolve this issue, we can leverage os.ModeCharDevice to determine whether STDIN is associated with a terminal or a pipe. Here's how:

package main

import (
    "fmt"
    "os"
)

func main() {
    stat, _ := os.Stdin.Stat()
    if (stat.Mode() & os.ModeCharDevice) == 0 {
        fmt.Println("data is being piped to stdin")
    } else {
        fmt.Println("stdin is from a terminal")
    }
}

Explanation:

• stat, _ := os.Stdin.Stat(): Retrieves the file info for STDIN.

• if (stat.Mode() & os.ModeCharDevice) == 0: Checks if the STDIN file mode does not have the os.ModeCharDevice bit set.

  • If STDIN is a pipe, its mode will typically not have the os.ModeCharDevice bit set.
  • If STDIN is a terminal, its mode will usually have the os.ModeCharDevice bit set.
• Based on this check, the program prints the appropriate message, indicating whether data is being piped to STDIN or if it is executed from a terminal.

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