<?php

$str= "spawn needle /var/www/html/trabalho/arquivo/emboss/needle/alvos.txt /var/www/html/trabalho/arquivo/emboss/needle/modelos.txt Needleman-Wunsch global alignment of two sequences Warning: Unknown swissprot line type ' ' Warning: Unknown swissprot line type ' ' Warning: Unknown swissprot line type ' ' Warning: Unknown swissprot line type ' ' Warning: Unknown swissprot line type ' ' Warning: Unknown swissprot line type ' ' Warning: Unknown swissprot line type ' ' Warning: Unknown swissprot line type ' ' Gap opening penalty [10.0]: 10.0 Gap extension penalty [0.5]: 0.5 Output alignment [hba_human.needle]:";


$posInicio  = strripos($str, "[");

$posFim  = strripos($str, "]");

$quant= ($posFim-$posInicio-1);


echo substr($str, $posInicio+1, $quant);