Bash Script to check Disk Usage

LinuxRSA · 03-17-2022, 07:14 AM

Hi All,

Trying to run the below script to notify us if the disk goes over 80% usage but only wish to see the file systems over 80%.

Code:

#!/bin/sh
df -H | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{ print $5 " " $1 }' | while read output;
do
  echo $output
  usep=$(echo $output | awk '{ print $1}' | cut -d'%' -f1  )
  partition=$(echo $output | awk '{ print $2 }' )
  if [ $usep -ge 80 ]; then
  echo "Running out of space \"$partition ($usep%)\" on $(hostname) as on $(date)"
  fi
done

When i run the script i get the below output:

Code:

linux@server03:~$ ./diskcheck.sh
0% udev
84% /dev/sda1
Running out of space "/dev/sda1 (84%)" on linux as on Thu Mar 17 12:16:49 UTC 2022
4% /dev/sda15
1% /dev/sdb1
84% localhost:/gv0
Running out of space "localhost:/gv0 (84%)" on linux as on Thu Mar 17 12:16:49 UTC 2022
linux@server03:~$

How do i only extract the 84% ?

Turbocapitalist · 03-17-2022, 07:23 AM

I would do it with AWK all the way through:

Code:

df -HT \
| awk '!/^F/ && $2!~/tmpfs/ && $6+0>=80 {
        print $7 " is almost full (" $6 ")"; }'

Or is there are reason to complicate it?

LinuxRSA · 03-17-2022, 07:31 AM

Hi Turbocapitalist

This works perfect, i have over complicated it. Thanks its looks good now.

Code:

linux@server03:~$ ./disk2.sh
/ is almost full (84%)
/mnt/gv0 is almost full (84%)
linux@server03:~$

syg00 · 03-17-2022, 07:55 AM

The problem with using specific checks is that that are specific.

tmpfs replaced ramdisk - but not entirely. What's next ?. Might never be a concern ... or not. What if the syntax of the report changes.
Stay aware.

pan64 · 03-17-2022, 08:00 AM

Code:

while read -r a b c d e f g; 
do 
    [[ "${f%%%}" -lt 80 ]] && continue
    [[ $b = tmpfs ]] && continue
    echo "$g is almost full ($f)"
done < <(df -HT)

LinuxRSA · 03-17-2022, 08:37 AM

How would i add the below into the script ?

echo 'Disk Healthy' if disk utilization is below 80%

echo 'Disk Issue' if disk utilization is above 80%

Instead of getting the output

Quote:

/ is almost full (84%)

it says Disk Healthy or Disk Issue ?

I tried this

Code:

linux@server03:~$ df -HT \
> | awk '!/^F/ && $2!~/tmpfs/ && $6+0>=80 {
>         print $7 " is almost full (" $6 ")"; }'
/ is almost full (84%)
/mnt/gv0 is almost full (84%)
cc-scilo@eun-p-ca88x-app-03:~$ if [ $6 -ge 80 ]; then echo 'Disk Healthy'; else echo 'Disk Issue'; fi
-bash: [: -ge: unary operator expected
Disk Issue
linux@server03:~$

Turbocapitalist · 03-17-2022, 09:01 AM

AWK is a scripting language with a lot of abbreviations. In pseudocode, the above would be

Code:

if $0 ~ !/^F/ 
 AND if $2!~/tmpfs/ 
 AND if $6+0>=80 THEN {
       print $7 " is almost full (" $6 ")";
}

The first line above checks if the whole line starts with a capital F
The second line checks if the second field contains the string "tmpfs"
The third line converts the sixth field to a number and then compares it to 80.
The fourth line needs no further explanation I would hope.

So you could add another check with similar conditions but checks for less than a value instead.

Please see one of excellent AWK guides in conjunction with the reference manual for the version of AWK on your particular system, 'man awk'.

PS. For actual disk health, see smartmontools instead.

pan64 · 03-17-2022, 09:41 AM

Quote:

Originally Posted by LinuxRSA

I tried this

Code:

linux@server03:~$ df -HT \
> | awk '!/^F/ && $2!~/tmpfs/ && $6+0>=80 {
>         print $7 " is almost full (" $6 ")"; }'
/ is almost full (84%)
/mnt/gv0 is almost full (84%)
cc-scilo@eun-p-ca88x-app-03:~$ if [ $6 -ge 80 ]; then echo 'Disk Healthy'; else echo 'Disk Issue'; fi
-bash: [: -ge: unary operator expected
Disk Issue
linux@server03:~$

$6 is a variable inside awk, cannot be used in the shell (because that is unavailable, and in shell $6 has another meaning).

LinuxRSA · 03-17-2022, 10:17 AM

Thanks, would something like this be possible to script ?

Detect the values above 80% using the below command, then take that output and send it to the if statement that will say Disk Healthy or Disk Issue ?

Code:

linux@server03:~$ df -HT | awk '{print $6}'
Use%
0%
11%
84%
1%
0%
0%
4%
1%
84%
0%
0%
linux@server03:~$

Based on the above output how do i use it to create a IF statement

Code:

df -HT | awk '{print $6}'  
(( TAKE THIS OUTPUT ))

if [ USE OUTPUT IN HERE ]; then
echo "Disk Issue"
else
echo "Disk Healthy"

pan64 · 03-17-2022, 10:29 AM

you can do it inside awk:

Code:

 awk '{ if ($6+0>10) { print "apple" } else { print "worm" } } '

boughtonp · 03-17-2022, 10:31 AM

Awk can be very powerful - you often don't need to switch between it and Bash...

Code:

df -h | awk '$5 > 80 {print}; $5 <= 80 {print $1,"ok"}'

My df outputs "Use%" in $5, not $6, but also accepts a "--output=FIELD_LIST" which a script should use to guarantee what is output.

edit: Just realised previous posts were using "df -HT" instead of "df -h" which explains the difference. I would still use --output to be on safe side.

LinuxRSA · 03-17-2022, 10:40 AM

Awesome Guys, this one is working as expected.

Code:

linux@server03:~$
linux@server03~$ df -HT | awk '{print $6}'
Use%
0%
10%
83%
1%
0%
0%
4%
1%
83%
0%
linux@server03:~$
linux@server03:~$ df -HT |  awk '{ if ($6+0>80) { print "Disk Issue" } else { print "Disk Healthy" } } '
Disk Healthy
Disk Healthy
Disk Healthy
Disk Issue
Disk Healthy
Disk Healthy
Disk Healthy
Disk Healthy
Disk Healthy
Disk Issue
Disk Healthy
linux@server03:~$

Thank you, much appreciated!

michaelk · 03-17-2022, 10:44 AM

Quote:

Detect the values above 80% using the below command, then take that output and send it to the if statement that will say Disk Healthy or Disk Issue ?

My only comment and depends on your perspective and how you define the term disk. The term disk for means a physical device and filesystem percent usage does not determine the health of a disk.

dc.901 · 03-17-2022, 10:51 AM

There is also "--output" option with df command...

For example:

Code:

$ df --output=pcent /
Use%
 10%

$ df -h --output=used /
 Used
  12G

You can also have specific columns with:

Code:

$ df -h --output=used,pcent /
 Used Use%
  12G  10%

michaelk · 03-17-2022, 11:29 AM

To expand on dc.901 post.

Code:

 df --type ext4 --output=source,pcent | awk '!/^F/ { if ($2+0>80) { print $1,"Full" } else { print $1,"Ok" } } '

This outputs only physical filesystems not temporary and you can expand filesystems with additional --type FS option if you have others besides ext4.