I have a PHP script getAnalytics.php that when called, returns a specific integer value. I want to be able to call getAnalytics.php in a bash script that runs continuously checking the PHP script every 30 seconds to see if the value returned has changed.

How would I go about doing this? Or would you recommend a different method?

  • 2
    Why not edit the php script to do a loop for this?
    – Tim
    Commented May 11, 2019 at 10:00

2 Answers 2


If you have no better indication (watching some log file e.g.) to get notification of a possible change just endlessly loop in bash:

while [ 1 ] ; do
   echo "result: $res"
   if [ "$old_result" != "$res" ]; then
     echo "result has changed"
   sleep 30

You will need Ctrl+C to exit. If you want to exit on a particular value (e.g. 42) printed by the script set res to some dummy value at the beginning and then test for [ "$res" != "42" ]

  • I keep getting /myapp/test.php: line 1: 345234: command not found result, Commented Dec 14, 2014 at 16:58
  • @TreyCopeland what happens when you run /myapp/test.php from the commandline? Does that file have a shebang line? If not it is not an executable script and you have to call it with php /myapp/test.php.
    – Anthon
    Commented Dec 14, 2014 at 17:21
  • Why while [ 1 ] ; rather than while :; or while true; ?
    – PM 2Ring
    Commented Dec 15, 2014 at 6:55
  • @PM2Ring Looks better after 30 years of usage?
    – Anthon
    Commented Dec 15, 2014 at 7:08
  • 1
    @PM2Ring I don't think that speed is an issue if the OP can use PHP. And this way, where to put the exit loop with testing on $res requires less explaining.
    – Anthon
    Commented Dec 15, 2014 at 7:21

If you could relax your requirements to a minute between runs, you can easily do this via a cron entry. The advantage of this process is that a program does not simply sit around (and possibly die) causing you to miss some data or window. Also no special steps would be required to start it up between reboots.

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