Error: integer expression expected

bash shell-script arithmetic floating-point

5,675

Solution 1

bash (contrary to ksh93 or zsh¹) can't do floating point arithmetics. awk can though, so you can do the whole thing in awk.

Also, you don't need to use top (and wait 1 second) to get the load. The canonical way to get the load is from uptime.

uptime | awk '{load=+$(NF-2)}
  load > 2 {print "CRITICAL: " load; exit 2}
  load > 1 {print "WARNING: " load; exit 1}
  {print "OK: " load; exit 0}
  END {if (!NR) {print "UNKNOWN"; exit 3}'
exit

^{¹ In zsh though, you need to use the (( loadavg > 2 )) instead of [ "$loadavg" -gt 2 ] syntax for comparing non-integers}

Solution 2

top -b -n1 | grep -i load | awk -F, '{print$4}'| awk -F: '{print $2}' returns nada, hence your errors.

Solution 3

Your loadavg is null, causes syntax errors by [:

$ top -b n1 | grep -i load | awk -F, '{print$4}'| awk -F: '{print $2}'
<blank line here>

You must change it to:

$ top -b n1 | grep -i load | awk -F, '{print$4}'| awk -F: '{print $1}'
 0.24

However, you should use newer test in your script, it can handle this problem:

$ [[ "" -gt 1 ]] || echo "OK"
OK

With older [:

$ [ "" -gt 1 ] || echo "OK"
bash: [: : integer expression expected
OK

Updated

bash can not handle floating point numbers, so your comparison (even with new test [[..]]) will show errors.

You can use another tools to do this task, like bc, awk...

Example:

$ [[ $(echo "3 > 1" | bc -l) == 1 ]] && echo OK
OK
$[[ $(echo "3 < 1" | bc -l) == 1 ]] || echo Not OK
Not OK

5,675

Mandar Shinde

Updated on September 18, 2022

Comments

Mandar Shinde over 1 year
I have written a script to determine the Load average on the server as follows:
```
#!/bin/bash

loadavg=`top -b -n1 | grep -i load | awk -F, '{print$4}'| awk -F: '{print $2}'`

if [ "${loadavg}" -le  1 ]
then
echo "OK - Load Average = ${loadavg} | Load_Average=${loadavg}"
exit 0;
elif [ "${loadavg}" -gt 1 ] && [ "${loadavg}" -le 2 ]
then
echo "WARNING - Load Average = ${loadavg} | Load_Average=${loadavg}"
exit 1;
elif [ "${loadavg}" -gt 2 ]
then
echo "CRITICAL - Load Average = ${loadavg} | Load_Average=${loadavg}"
exit 2;
else
echo "UNKNOWN - Load Average = NaN | Load_Average=NaN"
fi
```
When the script is executed, it displays following error:
```
./loadavg.sh
./loadavg.sh: line 5: [:  0.06: integer expression expected
./loadavg.sh: line 9: [:  0.06: integer expression expected
./loadavg.sh: line 13: [:  0.06: integer expression expected
UNKNOWN - Load Average = NaN | Load_Average=NaN
```
- jasonwryan almost 10 years
  
  top -b n1 | awk -F, '/load/ {print $4}' is a lot cleaner...
- Felix Frank almost 10 years
  
  How about loadavg=$( cut -d' ' -f1 </proc/loadavg ) - and no, still not an integer expression. It's a fixpoint. If you want to use -le and friends, consider cut -d' ' -f1 </proc/loadavg | cut -d. -f1, i.e. just drop everything after the integer part.
- Stéphane Chazelas almost 10 years
  
  Nagios alread has a check_load. Why are you making your own?
- Stéphane Chazelas almost 10 years
  
  Do the whole thing in awk. awk can do floating points, bash or [ cannot.
- Stéphane Chazelas almost 10 years
  
  You can get the load from uptime, not need to run one iteration of top for that.
- Mandar Shinde almost 10 years
  
  @StéphaneChazelas: Well spotted! I am doing this just for fun.
Mandar Shinde almost 10 years

top -b -n1 | grep -i load | awk -F, '{print$4}'| awk -F: '{print $2}' is printing 0.37 while top -b n1 | grep -i load | awk -F, '{print$4}'| awk -F: '{print $1}' prints load average. While the top -b -n1 | grep -i load output is top - 15:02:31 up 2 days, 23:15, 1 user, load average: 0.37, 0.42, 0.38.
Mandar Shinde almost 10 years

top -b -n1 | grep -i load is displaying top - 15:02:31 up 2 days, 23:15, 1 user, load average: 0.37, 0.42, 0.38.
cuonglm almost 10 years

@MandarShinde: Yes, because you are parsing the output of top, it can produce different output. I tested in my Fedora machine. The main thing I want to show is you should using new test [[..]] instead of [..].
Mandar Shinde almost 10 years

When I replaced every [ with [[ and every ] with ]], it displayed the error: ./loadavg.sh: line 5: [[: 0.00: syntax error: invalid arithmetic operator (error token is ".00"). Tested on Red Hat Enterprise Linux Server release 6.5.
cuonglm almost 10 years

@MandarShinde: bash can not understand float number, bash treat it as string, causing this error.
Mandar Shinde almost 10 years

How should deal with this issue?
schaiba almost 10 years

As said above, if you want to use floats with bash, use bc for example.
Felix Frank almost 10 years

On Linux, looking up /proc/loadavg will be more economic than shelling out to uptime, albeit less portable.
Stéphane Chazelas almost 10 years

@MandarShinde, that depends on the top implementation. That also depends on whether there are processes with load in their name or username. Though you're right that it's not the problem the OP is facing.