(PHP 4, PHP 5, PHP 7, PHP 8)
posix_isatty — Determine if a file descriptor is an interactive terminal
Determines if the file descriptor file_descriptor refers to a valid
terminal type device.
Returns true if file_descriptor is an open descriptor connected
to a terminal and false otherwise.
| Version | Description |
|---|---|
| 8.4.0 |
Set errno (error number) to EBADF when the
file descriptor/stream passed is invalid.
|
| 8.3.0 |
Type error E_WARNINGs are now raised for integer
coercions following the usual PHP type coercion semantics.
|
Can be useful to determine whether output is being piped elsewhere, for PHP shell scripts, for example;#!/usr/local/bin/php<?phpif ( !posix_isatty(STDOUT) ) { fwrite(STDOUT, "Invalid TTY\n"); exit(2);}fwrite(STDOUT, "Enter you name\n");$name = fgets(STDIN);fwrite(STDOUT,"Hello $name\n");exit(0);?>If this script is like:script.php > outfileoutfile will contain "Invalid TTY"It's quite complicated to understand its movements. But it determines if the file_descriptor is open AND connected to a terminal.Thus, while receiving data from the STDIN, for example, it will return false.This move is useful to optionally pipe STDIN to a PHP script, to avoid hanging when nothing is from STDIN.<?php// Simply echoes the contents from STDIN if any// and "no stdin" if not.echo (posix_isatty(STDIN)) ? 'no stdin' . PHP_EOL : file_get_contents('php://stdin');?>