If I have this on my webpage :
$f = popen("/home/username/bin/something --json arg1 arg2", "rb");
while (($line = fgets($f)) !== false) {
$event = json_decode($line);
// do something
}
fclose($f);
If the the browser closes unexpectedly, will the execution of /home/username/bin/something stop ?I need it to be finished even if the browser tab closes.
Related
I'm writing a PHP script and I would like to be able to optionally use a file as the script input. This way:
$ php script.php < file.txt
I'm, actually, able to do that using file_get_contents:
$data = file_get_contents('php://stdin');
However, if I don't pass a file to the input, the scripts hangs indefinetelly, waiting for an input.
I tried the following, but it didn't work:
$data = '';
$in = fopen('php://stdin', 'r');
do {
$bytes = fread($in, 4096);
// Maybe the input will be empty here?! But no, it's not :(
if (empty($bytes)) {
break;
}
$data .= $bytes;
} while (!feof($in));
The script waits for fread to return a value, but it never returns. I guess it waits for some input the same way file_get_contents does.
Another attempt was made by replacing the do { ... } while loop by a while { ... }, checking for the EOF before than trying to read the input. But that also didn't work.
Any ideas on how can I achieve that?
You can set STDIN to be non-blocking via the stream_set_blocking() function.
function stdin()
{
$stdin = '';
$fh = fopen('php://stdin', 'r');
stream_set_blocking($fh, false);
while (($line = fgets($fh)) !== false) {
$stdin .= $line;
}
return $stdin;
}
$stdin = stdin(); // returns the contents of STDIN or empty string if nothing is ready
Obviously, you can change the use of line-at-a-time fgets() to hunk-at-a-time fread() as per your needs.
I use PHP function flock to check if another process is running, but sometimes the file is used by MySQL process. This is the result for lsof command :
And this is my php script:
$list = [];
$handle_list = fopen("$backup path/log/list.txt", "a+");
if(flock($handle_list, LOCK_EX | LOCK_NB))
{
while(($buffer = fgets($handle_list, 4096)) !== false)
{
$buffer = str_replace(["\r", "\n"], '', $buffer);
$list[] = $buffer;
}
}
else
{
echo date('Y-m-d H:i:s'). " : ERROR : Another process running\n\n\n";
exit(-1);
}
Without MySQL process locking the file, the script work fine. I don't know when can MySQL use a file?
I want impose a time limit to a process reading using fgets opened by popen in PHP.
I have the next code:
$handle = popen("tail -F -n 30 /tmp/pushlog.txt 2>&1", "r");
while(!feof($handle)) {
$buffer = fgets($handle);
echo "data: ".$buffer."\n";
#ob_flush();
flush();
}
pclose($handle);
I tried without success:
set_time_limit(60);
ignore_user_abort(false);
The process is as follow:
The browser send a GET request waiting for a Answer in HTML5 Server side
events format.
The request is received by AWS Load Balancer and is
forwarded to EC2 instances.
The answer is the last 30 lines of the file
The browser receive it in 30 messages and the connection is persisted.
If tail command sends a new line it is returned else fgets wait undefined time until new line is returned from tail command.
AWS Load Balancer after 60 seconds of network inactivity (No new lines in 60 seconds) closes the connection to the browser. The connection to EC2 instance is not closed.
The browser detect that the connection is closed and it opens a new connection, the process go back to step 1.
AS this steps describe, the connection between AWS Load Balancer and EC2 instance is never closed, after a few hours/days there is hundreds and hundreds of tail and httpd process running and the server start not answering.
Of course it appear to be a AWS Load Balancer bug, but I don't want start a process to gain the attention from Amazon and wait for a fix.
My temporary solution is do a sudo kill tail to kill the process before the server becomes unstable.
I think PHP doesn't stop the script because PHP is "blocked" waiting for fgets to finish.
I know that the time limit of AWS Load Balancer is editable, but I want keep in the default value, even a higher limit is not going to fix the problem.
I don't know if I need change the question to How to execute a process in linux with a time limit / timeout?.
PHP 5.5.22 / Apache 2.4 / Linux Kernel 3.14.35-28.38.amzn1.x86_64
Tested with PHP 5.5.20:
//Change configuration.
set_time_limit(0);
ignore_user_abort(true);
//Open pipe & set non-blocking mode.
$descriptors = array(0 => array('file', '/dev/null', 'r'),
1 => array('pipe', 'w'),
2 => array('file', '/dev/null', 'w'));
$process = proc_open('exec tail -F -n 30 /tmp/pushlog.txt 2>&1',
$descriptors, $pipes, NULL, NULL) or exit;
$stream = $pipes[1];
stream_set_blocking($stream, 0);
//Call stream_select with a 10 second timeout.
$read = array($stream); $write = NULL; $except = NULL;
while (!feof($stream) && !connection_aborted()
&& stream_select($read, $write, $except, 10)) {
//Print out all the lines we can.
while (($buffer = fgets($stream)) !== FALSE) {
echo 'data: ' . $buffer . "\n";
#ob_flush();
flush();
}
}
//Clean up.
fclose($stream);
$status = proc_get_status($process);
if ($status !== FALSE && $status['running'] === TRUE)
proc_terminate($process);
proc_close($process);
Rather than using a process file pointer, I went with my "multitasking" approach. I use this code to spawn other "processes" Kind of a multitasking cheat.
I call a Script, hang.php, that just hangs for 90 seconds: sleep(90).
You may want to adjust the stream and stream_select timeouts.
Create stream(s)
header('Content-Type: text/plain; charset=utf-8');
$timeout = 20;
$result = array();
$sockets = array();
$buffer_size = 8192;
$id = 0;
$stream = stream_socket_client("ispeedlink.com:80", $errno,$errstr, $timeout,
STREAM_CLIENT_ASYNC_CONNECT|STREAM_CLIENT_CONNECT);
if ($stream) {
$sockets[$id++] = $stream; // supports multiple sockets
$http = "GET /testbed/hang.php HTTP/1.0\r\nHost: ispeedlink.com\r\n\r\n";
fwrite($stream, $http);
}
else {
echo "$id Failed\n";
}
Additional scripts can be run by adding the stream: $sockets[$id++] = $stream;
Below will put anything read in to the $result[$id] array.
Monitor the streams:
while (count($sockets)) {
$read = $sockets;
stream_select($read, $write = NULL, $except = NULL, $timeout);
if (count($read)) {
foreach ($read as $r) {
$id = array_search($r, $sockets);
$data = fread($r, $buffer_size);
if (strlen($data) == 0) { // either reads data or EOF
echo "$id Closed: " . date('h:i:s') . "\n\n\n";
fclose($r);
unset($sockets[$id]);
}
else {
$result[$id] .= $data;
}
}
}
else {
echo 'Timeout: ' . date('h:i:s') . "\n\n\n";
break;
}
}
echo system('ps auxww');
.
When I want to kill a process I use system('ps auxww') to get the pid and kill it with system("kill $pid")
kill.php
header('Content-Type: text/plain; charset=utf-8');
//system('kill 220613');
echo system('ps auxww');
Let's consider a sample php script which deletes a line by user input:
$DELETE_LINE = $_GET['line'];
$out = array();
$data = #file("foo.txt");
if($data)
{
foreach($data as $line)
if(trim($line) != $DELETE_LINE)
$out[] = $line;
}
$fp = fopen("foo.txt", "w+");
flock($fp, LOCK_EX);
foreach($out as $line)
fwrite($fp, $line);
flock($fp, LOCK_UN);
fclose($fp);
I want to know if some user is currently executing this script and file "foo.txt" is locked, in same time or before completion of its execution, if some other user calls this script, then what will happen?
Will second users process wait for unlocking of file by first users? or line deletion by second users input will fail?
If you try to acquire an exclusive lock while another process has the file locked, your attempt will wait until the file is unlocked. This is the whole point of locking.
See the Linux documentation of flock(), which describes how it works in general across operating systems. PHP uses fcntl() under the hood so NFS shares are generally supported.
There's no timeout. If you want to implement a timeout yourself, you can do something like this:
$count = 0;
$timeout_secs = 10; //number of seconds of timeout
$got_lock = true;
while (!flock($fp, LOCK_EX | LOCK_NB, $wouldblock)) {
if ($wouldblock && $count++ < $timeout_secs) {
sleep(1);
} else {
$got_lock = false;
break;
}
}
if ($got_lock) {
// Do stuff with file
}
i want to run a command in console then 'echo' it via a log file. i wrote following code. but it doesnt work. if i put command direct in 'popen' it waits first the page load..
what can be done ?
shell_exec("nohup $cmd > out.log 2>&1");
if( ($fp = popen("tail out.log" , "r")) ) {
while( strpos($txt, "FINISH") == false){
$txt = fread($fp, 1024);
echo $txt;
flush();
}
}