I have two computers. On the first computer I have apache running with all my web code. On the second computer I have large amounts of data stored with a retrieval script (the script usually takes hours to run). I am essentially creating a web UI to access this data without any time delay.
so I call:
exec("bash initial.bash");
this is a driver script that is in my Apache folder. It calls the script on the other computer. calling: ssh otherMachine temp.bash&
this script invokes the data retrieval script on the second computer.
If I call initial.bash in the terminal, everything works smoothly and successfully, but if I call it in my PHP file, then all my commands in initial.bash run, with the exception of ssh otherMachine temp.bash&. I put the & at the end of that, so that temp.bash will run in the background, since it does take a few hours to complete.
I am not sure why the nested script is not running when invoked by Apache. Is there a better alternative than using exec or shell_exec to call a script, which ultimately calls another script. The reason I don't call a script on the second machine directly is because of the time it takes the program to run. Shell_exec does not render the php page until the script is complete.
My guess is that SSH doesn't like the user php is running under? You say it works fine from the terminal - are you logged in as the same php user?
You might also find a message queue of some sort a better solution.
You may use cron (scheduled) jobs. Cron job retrieve the data periodically via using your bash script.
Additionally try to exec("/bin/bash /path/to/script.sh"); Maybe php does not find the path of bash. You have to look apache logs for additional info.
A couple suggestions:
Try putting the full path to ssh (/usr/bin/ssh or wherever it's installed instead of just ssh)
Make sure the user apache/PHP is running under is set up correctly to ssh to othermachine without asking for a password. Obviously if SSH asks for a password, there is nobody there to type it in, so it will just appear to have done nothing.
Try redirecting outputs as well -- ssh othermachine temp.bash >/dev/null 2>&1 &
Try some different flags to ssh. Like -n which is specifically designed for running a command over ssh in the background.