Shell script error while executing

Question

I have written a shell script but it is giving error, following is my code

#!/bin/bash
CPU= cat /proc/loadavg | awk '{print$1}'
if  [ $CPU -gt 6 ]
then
echo "Current CPU is: $CPU" | mail -s "CPU Load is Getting High" [email protected]
fi

When I execute this script, it gives the following error:

cpu_load.sh: line 3: [: -gt: unary operator expected

That means $CPU has non numeric data. Print it before if using echo "<$CPU>" — anubhava
– anubhava, Commented Aug 21, 2014 at 21:41
Are you missing a couple of back-ticks in the assignment of CPU? — Some programmer dude
– Some programmer dude, Commented Aug 21, 2014 at 21:42

clt60 · Accepted Answer · 2014-08-21 21:43:09Z

1

Maybe?

CPU=$(cat /proc/loadavg | awk '{print $1}')

The $(...) called as command substituion - assigning the result of the command to variable

answered Aug 21, 2014 at 21:43

clt60

64.3k17 gold badges114 silver badges206 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Slava Semushin · Accepted Answer · 2014-08-21 21:44:24Z

0

It means that command cat /proc/loadavg | awk '{print$1}' has returned nothing. To workaround it you could assign to variable default value:

if  [ ${CPU:-0} -gt 6 ]

or you could check variable before use it, like that:

if  [ -n "$CPU" -a "$CPU" -gt 6 ]

answered Aug 21, 2014 at 21:44

Slava Semushin

15.2k7 gold badges56 silver badges69 bronze badges

Collectives™ on Stack Overflow

Shell script error while executing

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related