topic Re: script execution fails when executed from crontab in Operating System - Linux

script execution fails when executed from crontab

Sunny Jaisinghani — Wed, 13 Jan 2010 16:52:42 GMT

I have scheduled a script to run in crontab. the script monitors the load average and sends an email if load avg is above certain limit.

#!/bin/bash
avg=`uptime | awk '{print $8" " $9 " "$10 $11 $12 }' | tr -s , " "`
cur=`more /proc/loadavg | awk '{print $1}' | tr -d , | cut -d. -f1`
str="============================="
info="Curent $avg"

if [ $cur -ge 6 ]; then
info1="Server load is high presently"
touch /tmp/tmp.00
echo -e "$str\n$info\n$info1\n$str\n" >> /tmp/tmp.00
ps aux | head -1 >> /tmp/tmp.00
ps aux | sort -rn +2 | head -10 >> /tmp/tmp.00;
mail -s "Alert: Load Average for `hostname` on `date` " email1 < /tmp/tmp.00;
mail -s "Alert: Load Average for `hostname` on `date` " email2 < /tmp/tmp.00;
rm -f /tmp/tmp.00
else
#echo -e "$str\n$info\n$str"
exit 0;
fi

when i execute this script i don get any error.
However, when it runs through cron it throws an error.

./monitor_loadavg.sh: line 7: [: too many arguments

i don see anything wrong with line 7.

Please suggest if i am doing anything wrong

Thanks
SUnny

Re: script execution fails when executed from crontab

Matti_Kurkela — Wed, 13 Jan 2010 17:26:15 GMT

The problem is probably in the content of the $cur variable somehow.

On line 3, you use the "more" command to read /proc/loadavg. When you're running the script in your session, "more" can find the $TERM and $LINES environment variables that identify your terminal type and the number of lines in your terminal window.

But when running from cron, there is no terminal, and those variables won't exist. I guess "more" might produce some extra output (a notification message or something). You don't need it anyway: this version of line 3 of your script should work just the same, but without the uncertain behavior of "more":

cur=$(awk '{print $1}' < /proc/loadavg | tr -d, | cut -d. -f1)

mK

Re: script execution fails when executed from crontab

Steven Schweda — Wed, 13 Jan 2010 17:28:06 GMT

> i don see anything wrong with line 7.

Probably because you don't see what "$cur"
is.

> if [ $cur -ge 6 ]; then

if [ "$cur" -ge 6 ]; then

But, if "cur" contains multiple tokens, then
you'll probably need to look more closely at
its definition.

Re: script execution fails when executed from crontab

Ivan Ferreira — Wed, 13 Jan 2010 18:24:59 GMT

Probably some of the commands for filling the cur variable is not working. This produces the error in line 7 as cur is empty or missformatted. Try adding the fill path to the more, awk, cut y tr commands.

Add an echo $cur on line 6 to debug the problem.

Re: script execution fails when executed from crontab

Dennis Handly — Sat, 16 Jan 2010 08:09:32 GMT

>MK: cur=$(awk '{print $1}' < /proc/loadavg | tr -d, | cut -d. -f1)

Besides this change, you can probably replace tr(1) and cut(1) by more awk functions.

Re: script execution fails when executed from crontab

Sunny Jaisinghani — Sat, 16 Jan 2010 17:25:01 GMT

Thanks Matti,

your suggestion worked for me.