AlmaLinux 8.6 : Logwatch , Disk Usage Check Script

Contents

1. Logwatch Install
2. Introduce disk usage check script
- 2.1 Script Creation
- 2.2 Execution Confirmation

1. Logwatch Install

① Install

# dnf install logwatch

1	# dnf install logwatch

② Edit configuration file

# cat /usr/share/logwatch/default.conf/logwatch.conf >> /etc/logwatch/conf/logwatch.conf
# vi /etc/logwatch/conf/logwatch.conf

●Per line 45
Insert "#" at the beginning of the "MailTo = root" line and set the email address you want to receive notifications under.
#MailTo = root
MailTo = <mail address>
●Per line 79 : Set the level of detail for log notifications
#Detail = Low
Detail = High

# cat /usr/share/logwatch/default.conf/logwatch.conf >> /etc/logwatch/conf/logwatch.conf

# vi /etc/logwatch/conf/logwatch.conf

●Per line 45

Insert "#" at the beginning of the "MailTo = root" line and set the email address you want to receive notifications under.

#MailTo = root

MailTo = <mail address>

●Per line 79 : Set the level of detail for log notifications

#Detail = Low

Detail = High

③ Output Logwatch reports

# logwatch --output stdout

1	# logwatch --output stdout

You will get the following message

################### Logwatch 7.6 (01/22/22) ####################
Processing Initiated: Fri May 13 09:41:46 2022
Date Range Processed: yesterday
( 2022-May-12 )
Period is day.
Detail Level of Output: 10
Type of Output/Format: stdout / text
Logfiles for Host: fedora
###########################################################

--------------------- Amavisd-new Begin ------------------------

<abbreviation>

-------------------- Disk Space Begin ------------------------
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/fedora_fedora-root 15G 4.4G 11G 30% /
/dev/nvme0n1p1 1014M 245M 770M 25% /boot
---------------------- Disk Space End -------------------------

###################### Logwatch End #########################

You will get the following message

################### Logwatch 7.6 (01/22/22) ####################

Processing Initiated: Fri May 13 09:41:46 2022

Date Range Processed: yesterday

( 2022-May-12 )

Period is day.

Detail Level of Output: 10

Type of Output/Format: stdout / text

Logfiles for Host: fedora

###########################################################

--------------------- Amavisd-new Begin ------------------------

-------------------- Disk Space Begin ------------------------

Filesystem Size Used Avail Use% Mounted on

/dev/mapper/fedora_fedora-root 15G 4.4G 11G 30% /

/dev/nvme0n1p1 1014M 245M 770M 25% /boot

---------------------- Disk Space End -------------------------

###################### Logwatch End #########################

④Test to see if the report arrives at the address you set. Check if you receive a log report email like the one above.

# /etc/cron.daily/0logwatch

1	# /etc/cron.daily/0logwatch

2. Introduce disk usage check script

2.1 Script Creation

# cd /var/www/system
# vi disk_capacity_check.sh

1 2	# cd /var/www/system # vi disk_capacity_check.sh

Contents of disk_capacity_check.sh

#!/bin/bash

#Designation of e-mail address to be notified
MAIL="<mail address>"

DVAL=`/bin/df / | /usr/bin/tail -1 | /bin/sed 's/^.* \([0-9]*\)%.*$/\1/'`

if [ $DVAL -gt 80 ]; then
echo "Disk usage alert: $DVAL %" | mail -s "Disk Space Alert in `hostname`" $MAIL
fi

#!/bin/bash

#Designation of e-mail address to be notified

MAIL="<mail address>"

DVAL=`/bin/df / | /usr/bin/tail -1 | /bin/sed 's/^.* $[0-9]*$%.*$/\1/'`

if [ $DVAL -gt 80 ]; then

echo "Disk usage alert: $DVAL %" | mail -s "Disk Space Alert in `hostname`" $MAIL

# chmod 700 disk_capacity_check.sh

1	# chmod 700 disk_capacity_check.sh

2.2 Execution Confirmation

①Check current utilization

# df -h

# df -h

It appears as follows

Filesystem                        Size       Used    Avail    Use%       Mounted on
devtmpfs                          875M          0     875M      0%             /dev
tmpfs                             893M          0     893M      0%         /dev/shm
tmpfs                             893M       8.8M     884M      1%             /run
tmpfs                             893M          0     893M      0%   /sys/fs/cgroup
/dev/mapper/almalinux_alma-root    17G       6.0G      12G     36%                /
/dev/nvme0n1p1                   1014M       257M     758M     26%            /boot
tmpfs                             179M          0     179M      0%   /run/user/1000

Filesystem Size Used Avail Use% Mounted on

devtmpfs 875M 0 875M 0% /dev

tmpfs 893M 0 893M 0% /dev/shm

tmpfs 893M 8.8M 884M 1% /run

tmpfs 893M 0 893M 0% /sys/fs/cgroup

/dev/mapper/almalinux_alma-root 17G 6.0G 12G 36% /

/dev/nvme0n1p1 1014M 257M 758M 26% /boot

tmpfs 179M 0 179M 0% /run/user/1000

②Create a dummy file to have at least 80% utilization (in the example, it is named "dummyfile" and is about 9G).

# dd if=/dev/zero of=dummyfile bs=1M count=9000

1	# dd if=/dev/zero of=dummyfile bs=1M count=9000

③Reaffirmation

# df -h

# df -h

Confirmation that it is at least 80%.

④Run disk space check script

# /var/www/system/disk_capacity_check.sh

1	# /var/www/system/disk_capacity_check.sh

You will receive an email to the email address you set up with the body of the message as "Disk usage alert: 93 %".

⑤Delete the "dummyfile" you created.

# rm -f dummyfile

1	# rm -f dummyfile

⑥Periodic Execution Setting

# crontab -e
30 2 * * * /var/www/system/disk_capacity_check.sh

1 2	# crontab -e 30 2 * * * /var/www/system/disk_capacity_check.sh

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