I am trying to move a file between directories on the same filesystem. The difficulty I am having is that when I use rename() the file access time is changed for that file on the filesystem.
I tried using shell_exec() with mv, though for some reason when I call mv in this way it copies the file and then deletes the original which takes much longer.
Is there any way to move the file quickly without changing the access time? Or can I change it back after calling rename()?
As a general rule the access time from a file must be changed when a function like rename(), or any other function that access a file, do it.
As for changing the access time of a file. This is only possible using the touch function, like described in the manual:
bool touch ( string $filename [, int $time = time() [, int $atime ]] )
Attempts to set the access and modification times of the file named in the filename parameter to the value given in time. Note that the access time is always modified, regardless of the number of parameters.
As you can see the time parameter is described in the manual as:
touch time
If time is not supplied, the current system time is used.
And here is an example from the same page of setting the access time one hour back from a file:
<?php
// This is the touch time, we'll set it to one hour in the past.
$time = time() - 3600;
// Touch the file
if (!touch('some_file.txt', $time)) {
echo 'Whoops, something went wrong...';
} else {
echo 'Touched file with success';
}
?>
However, be aware that the touch function, as described, attempts to change the file. If you have no permission for example the function will return false. (and won't change the file time)
Cheers
You can temporarily store the access time of the file using fileatime and modify it using touch.
$filename = 'somefile.txt';
$original_timestamp = fileatime($filename);
// .. modify file here ..
touch($filename, $original_timestamp);
Related
I've build an FTP class in PHP with a function to download files from the FTP server.
This is the function so far
public function downloadData($serverFile, $localPath)
{
$fileName = basename($serverFile);
$file = $localPath.$fileName;
$download = false;
if(!file_exists($file))
{
// try to download $server_file and save to $local_file
if(ftp_get($this->connection_id, $file, $serverFile, FTP_BINARY)) {
$download = true;
}
}
return $download;
}
Basically it works fine, but when saving the data the "last change date" of the file is set to the current date/time. I somehow want to prevent this, because the original date is important for my needs.
Is there a way to keep the original modified date of the file?
It sounds like you believe there's something overwriting the timestamp. There's not. The timestamp is simply not transferred at all during an FTP download. So the local file has last modification time matching the transfer time (= the last time the local file was modified).
But you can of course explicitly set the timestamp after the download finishes.
Use ftp_mdtm to retrieve the timestamp of source file on FTP server.
Use touch to set the timestamp of target local file.
touch($file, ftp_mdtm($this->connection_id, $serverFile));
You cannot stop the system from updating the modified date when modifying a file. However, it depends drastically on why you need the creation date?
Unfortunately if you are running on Linux/Unix you cannot access the creation date information as only the last modified date is stored. However for Windows you can use filectime and it will return the creation time
I have a php script i run every 5 minutes with Cron from a folder. In the folder there is several images and i add more as time goes.
I was wondering how i can make the php script in the beginning check if NEW files exist after the last time the script was run? If new files exist the script should just go on and if no new files exist then it should not go on. I tried searching around but i cant find anything regarding php.
Anyone that know a quick solution to this problem maybet ?
If the new files are also created with a new timestamp, you can use filemtime() to fetch only files that were created/modified in a specified window of time.
Example:
$files = glob("folder/*.jpg");
$files = array_filter($files, function ($file) { return filemtime($file) >= time() - 5*60; /* modified in the last 5 minutes */ });
if ($files)
{
// there are new files! $files is an array with their names
}
To make sure you won't miss any file, you might want to store the time from last run somewhere, so in case cron delays a second or two and new files were created precisely within that window, you won't lose track of them.
Update for comments:
Now, to store the time from last check, thats up to you to decide how you will do that, you can use database, file, some sort of environment variable etc., but here is an example of how you can do something really simple storing time() in a file:
$last = (int)file_get_contents('folder/timestamp.txt');
file_put_contents('folder/timestamp.txt', time());
$files = glob("folder/*.jpg");
$files = array_filter($files, function ($file) { return filemtime($file) > $last; });
if ($files)
{
// there are new files! $files is an array with their names
}
Just make sure your PHP script can modify folder/timestamp.txt and with this script it will always process new files modified since the last run, no matter how long ago it happened.
Method :
store current time whenever the cron executed in a file or database.
every time when cron starts get the last executed time of the cron from your file or database
count the file which creates after last execution time.
if count greater than 0. process the cron. other wise stop.
You could keep track of the time the script was last run and use filemtime to check if the file was updated or created after your last execution.
http://php.net/manual/en/function.filemtime.php
int filemtime ( string $filename )
Use filemtime() as follows,You will get the added time as date format.
$file_time = date ("F d Y H:i:s.", filemtime($filename);
I want to write one PHP script that will tell me how many folders getting created today( not modified one !! ).
Ex. Suppose if gave the path ( like c:\Data ) so my script must be continuously checking that
give path for if it is new entry of any folder. I have used http://php.net/manual/en/function.date-diff.php. But getting result for modified folders as well.
Quote from #Alin Purcaru:
Use filectime. For Windows it will return the creation time, and for Unix the change time which is the best you can get because on Unix there is no creation time (in most filesystems).
Using a reference file to compare the files age allows you to detect new files whidout using a database.
// Path to the reference file.
// All files newer than this will be treated as new
$referenceFile="c:\Data\ref";
// Location to search for new folders
$dirsLocation="c:\Data\*";
// Get modification date of reference file
if (file_exists($referenceFile))
$referenceTime = fileatime($referenceFile);
else
$referenceTime = 0;
// Compare each directory with the reference file
foreach(glob($dirsLocation, GLOB_ONLYDIR) as $dir) {
if (filectime($dir) > $referenceTime)
echo $dir . " is new!";
}
// Update modification date of the reference file
touch($referenceFile);
Another solution could be to use a database. Any folders that are not in the database are new. This ensures to not catch modified folders.
You might want to try getting your script launched with cron like every one minute and check the difference between directory lists (from before and current I mean), not the dates. It's not a perfect solution, but it will work.
Check directories arays with:
$dirs = array_filter(glob('*'), 'is_dir');
Compare them later with array_diff
I have a script that re-writes a file every few hours. This file is inserted into end users html, via php include.
How can I check if my script, at this exact moment, is working (e.g. re-writing) the file when it is being called to user for display? Is it even an issue, in terms of what will happen if they access the file at the same time, what are the odds and will the user just have to wait untill the script is finished its work?
Thanks in advance!
More on the subject...
Is this a way forward using file_put_contents and LOCK_EX?
when script saves its data every now and then
file_put_contents($content,"text", LOCK_EX);
and when user opens the page
if (file_exists("text")) {
function include_file() {
$file = fopen("text", "r");
if (flock($file, LOCK_EX)) {
include_file();
}
else {
echo file_get_contents("text");
}
}
} else {
echo 'no such file';
}
Could anyone advice me on the syntax, is this a proper way to call include_file() after condition and how can I limit a number of such calls?
I guess this solution is also good, except same call to include_file(), would it even work?
function include_file() {
$time = time();
$file = filectime("text");
if ($file + 1 < $time) {
echo "good to read";
} else {
echo "have to wait";
include_file();
}
}
To check if the file is currently being written, you can use filectime() function to get the actual time the file is being written.
You can get current timestamp on top of your script in a variable and whenever you need to access the file, you can compare the current timestamp with the filectime() of that file, if file creation time is latest then the scenario occured when you have to wait for that file to be written and you can log that in database or another file.
To prevent this scenario from happening, you can change the script which is writing the file so that, it first creates temporary file and once it's done you just replace (move or rename) the temporary file with original file, this action would require very less time compared to file writing and make the scenario occurrence very rare possibility.
Even if read and replace operation occurs simultaneously, the time the read script has to wait will be very less.
Depending on the size of the file, this might be an issue of concurrency. But you might solve that quite easy: before starting to write the file, you might create a kind of "lock file", i.e. if your file is named "incfile.php" you might create an "incfile.php.lock". Once you're doen with writing, you will remove this file.
On the include side, you can check for the existance of the "incfile.php.lock" and wait until it's disappeared, need some looping and sleeping in the unlikely case of a concurrent access.
Basically, you should consider another solution by just writing the data which is rendered in to that file to a database (locks etc are available) and render that in a module which then gets included in your page. Solutions like yours are hardly to maintain on the long run ...
This question is old, but I add this answer because the other answers have no code.
function write_to_file(string $fp, string $string) : bool {
$timestamp_before_fwrite = date("U");
$stream = fopen($fp, "w");
fwrite($stream, $string);
while(is_resource($stream)) {
fclose($stream);
}
$file_last_changed = filemtime($fp);
if ($file_last_changed < $timestamp_before_fwrite) {
//File not changed code
return false;
}
return true;
}
This is the function I use to write to file, it first gets the current timestamp before making changes to the file, and then I compare the timestamp to the last time the file was changed.
Is there any way to check id a file is being accessed or modified by another process from a php script. i have attempted to use the filemtime(), fileatime() and filectime() functions but i have the script in a loop which is checking continuously but it seems once the script has been executed it will only take the time from the first time the file was checked.. an example would be uploading files to a FTP or SMB share i attempted this below
while(1==1)
{
$LastMod = filemtime("file");
if(($LastMod +60) > time())
{
echo "file in use please wait... last modified : $LastMod";
sleep(10);
}else{
process file
}
}
I know the file is constantly changing but the $LastMod variable is not updating but end process and execute again will pick up a new $LastMod from the file but dosnt seem to update each time the file is checked in the loop
I have also attempted this with looking at filesize() but get the same symptoms i also looked into flock() but as the file is created or modified outside PHP I don't see how this would work.
If anyone has any solutions please let me know
thanks Vip32
PS. using PHP to process the files as requires interaction with mysql and querying external websites
The file metadata functions all work off stat() output, which caches its data, as a stat() call is a relatively expensive function. You can empty that cache to force stat() to fetch fresh data with clearstatcache()
There are other mechanisms that allow you to monitor for file changes. Instead of doing a loop in PHP and repeatedly stat()ing, consider using an external monitoring app/script which can hook into the OS-provided mechanism and call your PHP script on-demand when the file truly does change.
Add clearstatcache(); to your loop:
while(true)
{
$LastMod = filemtime("file");
clearstatcache();
if(($LastMod +60) > time())
{
echo "file in use please wait... last modified : $LastMod";
sleep(10);
}else{
process file
}
}