Need to track what PHP script is generating a file on nix
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You want something like DTRACE, that's going to be tough.
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@guyinpv maybe fswatch could help.
i think most distros have it in the repository.
http://emcrisostomo.github.io/fswatch/ -
I thought maybe just a simply stack trace log that could be "turned on" in Apache and/or PHP for temporary time like a few days, then turn it back off.
Logging all PHP functions for multiple days would likely produce a mountain of data, so I'd have to figure out how to save that and search it.
Wouldn't the Zend engine or some other PHP diagnostic monitoring tool be able to do this? I think it's something that can be done using Apache/PHP tools rather than underlying OS tools, I don't know.
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You can add this manually into the code yourself: http://php.net/manual/en/function.debug-print-backtrace.php
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This isn't a very typical task, it's a bit of a weird thing to want. You can't get this normally with any language without building it into the application itself or tracking system calls.
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I do understand the initial intention to get rid of those files by completely eliminating their source. Try this https://wordpress.org/plugins/string-locator/ to search for "/var/tmp/" hardcoded anywhere throughout the Wordpress installation. If not successful at the moment, you might simply automate their deletion with some cron job until you get to know what produces them.
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@darek-hamann said in Need to track what PHP script is generating a file on nix:
I do understand the initial intention to get rid of those files by completely eliminating their source. Try this https://wordpress.org/plugins/string-locator/ to search for "/var/tmp/" hardcoded anywhere throughout the Wordpress installation. If not successful at the moment, you might simply automate their deletion with some cron job until you get to know what produces them.
This was the first thing I tried. I searched through the entire themes folder and plugins folder for any reference to 'tmp' and other variations. But no luck.
The problem with WP is that everything is cobbled together from variables and system calls and WP functions. So most likely there is no place where the folder path is selected explicitly where I can search for it in this way. -
@mlnews said in Need to track what PHP script is generating a file on nix:
You can add this manually into the code yourself: http://php.net/manual/en/function.debug-print-backtrace.php
Nice, but where would I call it? So many different plugins and such, would be very hard to implement. But it only gives a backtrace, that doesn't exactly tell me when a function is writing to the file system.
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@guyinpv said in Need to track what PHP script is generating a file on nix:
@mlnews said in Need to track what PHP script is generating a file on nix:
You can add this manually into the code yourself: http://php.net/manual/en/function.debug-print-backtrace.php
Nice, but where would I call it? So many different plugins and such, would be very hard to implement. But it only gives a backtrace, that doesn't exactly tell me when a function is writing to the file system.
That's the hard part, it has to be everywhere. This isn't a trivial thing to add to software.
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Depending on the VPS's PHP implementation the child processes may or may not contain some useful stuff in the command line, such as which script is being executed.
Would it be helpful for you to get the PID's of any processes which open any file in a target dir, then log the full command line of that PID to a file?
If so, you can run the code below.
You should run this momentarily, exit with "CTRL-C" and check the log output. Loads of stuff writes to '/tmp/' and this will log all of it, so you might very likely fill the disk if you run out for a coffee and leave it running.
Ideally you should have a second SSH session to the VPS so you can kill it if necessary, and use 'tail -f /tmp/test/log/lsof.log' to monitor it's output in realtime.
watch -n 10 'for pid in $(lsof +D /tmp/ 2>/dev/null| awk '''/[0-9]/{print $2}'''); do if [ -n "$pid" ]; then ps f -p $pid >> /tmp/test/log/lsof.log 2>/dev/null; else sleep 0;fi;done'
The VPS probably doesn't have 'watch' installed, which runs the command every -n seconds. The rest of the commands used here should be on more or less any linux server, so you can use a while loop instead if necessary:
while true;do for pid in $(lsof +D /tmp/ 2>/dev/null| awk '/[0-9]/{print $2}'); do if [ -n "$pid" ]; then ps f -p $pid >> /tmp/path/to/log/lsof.log 2>/dev/null; else sleep 10;fi;done; done
Replace '/tmp/path/to/log/lsof.log' with whatever you want the logfile to be. '/tmp/' is the target dir to watch.
Example output is:
PID TTY STAT TIME COMMAND
25394 pts/46 R+ 0:00 dd if=/dev/urandom of=/tmp/test/test.php bs=512 count=100000
