Problem "$value=`mpstat 1 1 | grep "Average"`;" Alias pipe return nothing
 

Hello guys, this is my script :

My problem is, if i execute in console , then it works fine, it return 0,99 . Fine for now, now, when I execute script ./graph.sh , it correctly write into mysql value 0,99. So now time to automatize, when i put it into cron (bcron), when it run script, it instead of "0,99" just "" , i have no idea where should be problem.

http://img87.imageshack.us/img87/7200/script.jpg

And I should not that if that $value is just "mpstat 1 1" without pipe it works fine

Cron doesn't inherit your user environment like you do when you login.

The most common problem in cron scripts is expectation of variables, especially PATH, that are populated by your login but are minimal in cron.

To solve this you can add a PATH= statement to your cron and insure the directories it includes are the ones that contain mpstat, awk, grep and any other command you're using in the file.

Alternatively you could put the full path to commands each time you use them or create variables for each full path to executable then use that variable in place of the command. e.g.
Then in command line:
Of course for that command line in that approach you'd want variables for grep and awk as well). You'd also need to create one for other commands used int he script such as mysql.

If there are other variables mysql or other commands rely upon from your login you'd want to include them in the script as well. PATH is just the most common one.

I changed it to this, but still, from console works, but from cron not, should I put that export somewhere else ?

A quick-and-dirty method of simulating your entire logged-on environment, including $PATH, is to change the first line of the script to That presumes you are using bash as your login shell, not sh. The -l (letter l) tells bash to "make this shell act as if it had been directly invoked by login". See GNU Bash Reference.

mysql needs to be treated in the same way as mpstat etc. or you could simply change it to (I'm guessing the location of mysql so please check it using type mysql at a command prompt)
When the job is run by cron, there is no terminal to send stdout to so it will bork on the echo commands unless you redirect the entire script output to a file in the crontab or explicitly in the script itself with something like

By cron :
In shell :

Or, somebody know any command which directly echo/return average value of all cores in % ?

Try using

set -xv

as the 2nd line in the script, and capture all the stdout/stderr of the script in cron eg

1 2 * * * /home/me/myscript.sh >/home/me/myscript.log 2>&1

I'd also specify bash as the shell rather than sh, there are a few differences. Your option of course.