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Working out percentage of memory utilization

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# 1  
Old 08-08-2017
Working out percentage of memory utilization
Hi there

I am middle of writing a script to allow me to see the % of the memory which is being used.

When I submit my script I don't get any errors but I just get a blank output.

Any pointers?

Code:
available=`free -m | grep available`

if [ "$available"="$new_linux_version_available" ]
then

mem_utalization=`sum=$(($mem_total/($mem_total - $mem_available) * 100))`

else
mem_buff_cache_used=`free -m  | grep ^-/+ | awk  '{print $3}'`
mem_utalization=`sum=$(((mem_buff_cache_used/($mem_buff_cache_used + $mem_buff_cache_free)) * 100))`

fi

echo $mem_utalization
echo $mem_buff_cache_used
echo $mem_buff_cache_free

Code:
[casupport@wycvlapph033 test]$ ./free_memory_script.sh



[casupport@wycvlapph033 test]$

No error message or anything comes back? All the variables work as they work in the command line

Code:
[casupport@wycvlapph033 ~]$ free -m  | grep ^-/+ | awk  '{print $3}'
7281
[casupport@wycvlapph033 ~]$ free -m  | grep ^-/+ | awk  '{print $4}'
8757
[casupport@wycvlapph033 ~]$

Cheers
Alex
# 2  
Old 08-08-2017
Is that the entire script? On top of variables used for calculations being undefined, I see syntactical errors as well as questionable formulae yielding values > 100% for e.g. memory utilization.
# 3  
Old 08-08-2017
Hi RudiC

Please see below the whole script

Code:
###########################################################################################
## VARIABLES
###########################################################################################
 new_linux_version_available="available"
new_linux_version_buffcache="buff/cache"
 ###########################################################################################
## Memory - TOTAL
###########################################################################################
mem_total=`free -m  | grep ^Mem | awk '{print $2}'`
 #echo $mem_total
 ###########################################################################################
## Memory - USED
###########################################################################################
mem_used=`free -m  | grep ^Mem | awk '{print $3}'`
 #echo $mem_used
 ###########################################################################################
## Memory - FREE
###########################################################################################
mem_free=`free -m  | grep ^Mem | awk '{print $4}'`
 #echo $mem_free
 ###########################################################################################
## Memory - BUFFER+CACHE
###########################################################################################
buff_cache=`free -m | grep buff/cache`
 if [ "$buff_cache"="$new_linux_version_buffcache" ]
then
 sum=`free -m  | grep ^Mem | awk '{print $6}'`
else
 mem_buffer=`free -m  | grep ^Mem | awk '{print $6}'`
mem_cache=`free -m  | grep ^Mem | awk '{print $7}'`
 sum=$(($mem_buffer + $mem_cache))
 fi
 #echo $sum
 ###########################################################################################
## Memory - AVAILABLE
###########################################################################################
available=`free -m | grep available`
 if [ "$available"="$new_linux_version_available" ]
then
 mem_available=`free -m  | grep ^Mem | awk '{print $7}'`
else
mem_buff_cache_free=`free -m  | grep ^-/+ | awk  '{print $4}'`
mem_available=`sum=$(($mem_buff_cache_free + $mem_free))`
 fi
 #echo $mem_available
###########################################################################################
## Memory - UTILIZATION
###########################################################################################
available=`free -m | grep available`
 if [ "$available"="$new_linux_version_available" ]
then
 mem_utalization=`sum=$(($mem_total/($mem_total - $mem_available) * 100))`
 else
mem_buff_cache_used=`free -m  | grep ^-/+ | awk  '{print $3}'`
mem_utalization=`sum=$(((mem_buff_cache_used/($mem_buff_cache_used + $mem_buff_cache_free)) * 100))`
 fi
 echo $mem_utalization
echo $mem_buff_cache_used
echo $mem_buff_cache_free

# 4  
Old 08-08-2017
Have you been able to identify the syntactical errors and the senseless formulae?

EDIT: I have to correct myself - those are not syntactical erors, but semantical / logical ones.
Last edited by RudiC; 08-08-2017 at 08:49 AM..
# 5  
Old 08-08-2017
Hi RudiC

I have only been able to spot one,

Quote:
mem_utalization=`sum=$(((mem_buff_cache_used/($mem_buff_cache_used + $mem_buff_cache_free)) * 100))`
There should have been a $ infront of the mem_buff
# 6  
Old 08-08-2017
In principle, yes. However, inside the ((...)) ("arithmetic expansion") you don't need the $ , see e.g. man bash.

But, you have picked the perfect line to illustrate what I was talking about:
To produce a value to be assigned to mem_utalization, you use (the deprecated `...` version of) "command substitution" which is the standard output of the command. Your command is a variable assignment (sum=...). What is the stdout of a variable assignment? Nothing! So, mem_utalization is empty.
The next one is $mem_total/($mem_total - $mem_available) which will result in a value above 100% given all values used are positive. Is that what you want?

In your above script you're running free, grep, and awk umpteen times, each causing a (costly) process creation - why not do it all in a single pass? Try
Code:
free | awk '/^Mem/ {print "Total:", $2, ", free:", $4, ", used:", $3, ", something:", ($2-$7)/$2*100, "%"}' OFMT="%.2f"
Total: 1918976 , free: 100452 , used: 955060 , something: 63.88 %

without assessing your interpretation of free's numbers / columns. You can even have the distinction between various linux versions done in that one small awk script ...
This User Gave Thanks to RudiC For This Post:
simpsa27
# 7  
Old 08-08-2017
Hi RudiC

Thank you for your reply and your help with this.

Just a quick question regarding the final part of this code:

Code:
($2-$7)/$2*100, "%"}' OFMT="%.2f"

($2 - $7) are we taking the second variable away from the seventh?

And the final part I don't quite understand is that two decimal places?

Cheers
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