Shell Programming and Scripting

#!/bin/bash
ADMIN="email address"

ALERT=85

df -H | grep '^/dev/sda1'  | awk ' { print $5 " " $1 } ' | while read output;
do
  #echo $output
  NUM= $( echo $output | awk ' { print $1 } ' | cut -d '%' -f1 )
  partition= $(echo $output | awk ' { print $2 } ' )
  if [ $NUM -ge $ALERT ]; then
    echo "Running out of space \"$partition ($NUM%)\" on $(hostname) as on $(date)" |
    mail -s "Alert: Almost out of disk space $NUM"  $ADMIN
  fi
done

#!/bin/bash

ALERT=40

df -H | grep '^/dev/sda7'  | awk ' { print $5 " " $1 } ' | while read output;
do
  echo $output
  NUM=`echo $output | awk ' { print $1 } ' | cut -d '%' -f1 `
#echo $NUM
  partition=`echo $output | awk ' { print $2 } '`
  if [ $NUM -ge $ALERT ]; then
    echo "Running out of space \"$partition ($NUM%)\" on $(hostname) as on $(date)"
  fi
done

msg=$(df -H | awk 'int($5) > 84 && /\dev\/sda/{print $NF,$5,";"}')
if [ ! -z "$msg" ]; then
           echo $msg # Do something here.
fi

#!/bin/bash
ADMIN="email address"

ALERT=85

df -H | awk '/^\/dev\/sda1/{print $1, int($5)}' | while read partition NUM
do
  if [ $NUM -ge $ALERT ]; then
    echo "Running out of space \"$partition ($NUM%)\" on $(hostname) as on $(date)" |
    mail -s "Alert: Almost out of disk space $NUM"  $ADMIN
  fi
done

 disk_usage=`df -H | grep "/dev/sda7" |  awk '{print $5}' | cut -d"%" -f1` | if [ $disk_usage -ge 85 ]; then echo "disk usage is high";else echo "Disk usage is not high"; fi

$ greetings=$(echo hi)
$ echo $greetings
hi
$ greetings= $(echo hi)
-bash: hi: command not found