cut.php：

#!/usr/bin/php <?php define("INPUT_FILE", "t.txt"); define("OUTPUT_FILE", "a.txt"); $pos = max(intval($argv[1]), 0); $len = max(intval($argv[2]), 0); $file_size = filesize(INPUT_FILE); if($pos >= $file_size) exit; $fp = fopen(INPUT_FILE, "rb"); $point = 0; //current byte position $string = ""; while(ftell($fp) < $file_size) { if($point >= $pos + $len) break;$byte = fread($fp, 1); //php version >= 5.4 $char = unpack("C", $byte)[1]; if($char <= 0x7f) { //single byte if($point >= $pos) $string .= $byte; $point += 1; continue; } else { //double bytes if($point >= $pos) { $string .= $byte.fread($fp, 1); } else { fseek($fp, 1, SEEK_CUR); } $point += 1; continue; } } fclose($fp); file_put_contents(OUTPUT_FILE, $string); ?>

原始檔t.txt內容：

dkei20王nnso

測試命令：

./cut.php 6 1

檢視結果：

hexdump -C t.txt && hexdump -C a.txt