我不希望php等待exec（）完成

Question

我正在Raspberry Pi上為數據記錄工具運行Web界面。 PHP5。

用戶按下一個調用PHP腳本的按鈕以運行一個進程（使用exec），然后返回生成的文件。 無論出於何種原因，exec（）函數都不會等待完成，並且腳本因未找到要查找的文件而失敗。

當我用簡單的腳本（例如print）替換腳本時，請等待5秒鍾，再執行print-然后它會等待exec（）完成。 唯一的區別是在我調用的python腳本中。 是否有人對造成這種情況的原因有任何見解？

PHP腳本：

<?php

    $file = "/var/tmp/logs/FaultLog.csv";

    exec("python /data/scripts/test.py", $output, $return);

    if (!file_exists($file)) {
        die ("Error: Fault log could not be created.");
    }

    $type = filetype($file);
    // Send file headers
    header("Content-type: $type");
    header("Content-Disposition: attachment;filename=FaultLog.csv");
    header("Content-Transfer-Encoding: binary"); 
    header('Pragma: no-cache'); 
    header('Expires: 0');
    // Send the file contents.
    set_time_limit(0); 
    readfile($file);
?>

有效的Python腳本：

import time
print "hello"
time.sleep(5)
print "goodbye"

Python腳本無效。 很長，但是我決定將所有內容都包括在內，以防萬一。

#!/usr/bin/env python

import sqlite3, subprocess, re, os

faultID = hours = minutes = 0

csv_path = "/var/tmp/logs/"
db_path = "/data/databases/FaultDictionary.db"

def parse_msg (line):

        global faultID, hours, minutes

        if (" 12 41 01 " in line):                        #single message
                #parse CAN data
                try:
                        data = line.split("  ")[4][12:17].replace(" ","")
                        faultID = int(data[2:] + data[:2], 16)
                except:
                        return "Error: Unable to parse data. Data: " + line

        elif (" 12 41 02 " in line):                      #single message
                #parse CAN data
                try:
                        data = line.split("  ")[4][12:17].replace(" ","")
                        hours = int(data[2:] + data[:2], 16)
                except:
                        return "Error: Unable to parse data. Data: " + line

        elif (" 12 41 03 " in line):                      #single message
                #parse CAN data
                try:
                        minutes = int(line.split("  ")[4][12:14], 16)
                except:
                        return "Error: Unable to parse data. Data: " + line

        elif ("581   [8]  80" in line):                           #crashed
                return "Error: Crashed motor controller. Please try again."
        else:
                return "Error: Unexpected message format, cannot decode reply from motor controller. Data: " + line

        return ""

conn = sqlite3.connect(db_path)
curs = conn.cursor()

#note time
p = subprocess.Popen("date +\"%Y-%m-%d %H:%M\"", stdout=subprocess.PIPE, shell=True)
(output, err) = p.communicate()
current_date = output

#Create needed folder structure
if not (os.path.exists(csv_path)):
        os.makedirs(csv_path)

csv_path += "FaultLog.csv"

with open(csv_path, 'w+') as file:
        file.write("Date:," + current_date[:10] + "\n")
        file.write("Time:," + current_date[11:] + "\n\n")

        #SEVCON Fault Retreival
        file.write('Hours Ago [h], Minutes & Seconds Ago, Fault ID, Fault Name, Fault Cause, Fault Remedy\n')

        #send password to gain access
        p = subprocess.Popen("cansend can0 601#2B005002DF4BEFFA", cwd="/data/can-utils/", stdout=subprocess.PIPE, shell=True)
        p = subprocess.Popen("candump -t A -n 1 -T 100 can0,581:7ff", cwd="/data/can-utils/", stdout=subprocess.PIPE, shell=True)
        (output, err) = p.communicate()

        for num in range(0,40):
                pass

                #select event through 4111
                p = subprocess.Popen("cansend can0 601#2B114100" + hex(num)[2:].zfill(2) + "00EFFA", cwd="/data/can-utils/", stdout=subprocess.PIPE, shell=True)
                p = subprocess.Popen("candump -t A -n 1 -T 100 can0,581:7ff", cwd="/data/can-utils/", stdout=subprocess.PIPE, shell=True)
                (output, err) = p.communicate()

                #send request for event ID through 4112
                p = subprocess.Popen("(sleep 0.1; cansend can0 601#4012410100000000; cansend can0 601#4012410200000000; cansend can0 601#4012410300000000;) &", cwd="/data/can-utils/", stdout=subprocess.PIPE, shell=True)
                p = subprocess.Popen("candump -t A -n 3 -T 500 can0,581:7ff", cwd="/data/can-utils/", stdout=subprocess.PIPE, shell=True)
                (output, err) = p.communicate()

                message = ""
                if len(output) > 0:  # got the response message

                        lines = output.strip().split("\n")

                        for line in lines:
                                message = parse_msg(line)

                else:
                        message = "Error: Did not receive reply from motor controller."

                if message == "":      
                        #query database for fault description and remedy
                        curs.execute("SELECT * FROM FaultDictionary WHERE faultID = '" + str(faultID) + "'")   #faultID, message, description, action
                        for row in curs: #only ever one, since unique
                                #record to csv
                                file.write(str(hours) + "," + str(minutes) + "," + str(row[0]) + "," + str(row[1]) + "," + str(row[2]) + "," + str(row[3]) + "\n")
                                #print str(hours) + "," + str(minutes) + "," + str(row[0]) + "," + str(row[1]) + "," + str(row[2]) + "," + str(row[3]) + "\n"
                else:
                        print message
                        break

        #BMS Fault Retrieval
        #file.write('\n\nFault ID\n')

if not message == "":
        os.remove(csv_path)

conn.close()

tldr; PHP exec（）函數調用python腳本。 Exec（）應該等待您調用的完成。 使用某些腳本，而不是其他腳本。

Answer 1

當沒有&傳遞給參數以強制程序/執行在后台發生時，Exec是一個同步阻塞調用。

這使我相信處理請求的Apache實例的所有者沒有執行Python腳本的權限。

您應該相應地調整腳本或Apache用戶的權限。