bash script which will highlight maximum disk usage line on output

Question

I am writing the bash script which will show the disk usage status. If the size of the filesystem is used more than 95% then that line should be highlighted only one time like below. Basically, I want my script to work same as command df -h but with highlighting maximum disk usage. And other filesystems also should be on output. Here is my script.

readarray -t disk <<< "$(df -h | awk '{print $5}' | tail -n +2 | tr -d %)"
  for i in "${disk[@]}"
  do
    if [ $i -gt 95 ]
      then
        df -h | grep --color -E "$i%|$" 
    fi
 done

# df -h

Filesystem               Size  Used Avail Use% Mounted on
devtmpfs                 3.9G     0  3.9G   0% /dev
tmpfs                    3.9G  140M  3.8G   4% /dev/shm
tmpfs                    3.9G  1.8M  3.9G   1% /run
tmpfs                    3.9G     0  3.9G   0% /sys/fs/cgroup
/dev/mapper/centos-root  128G  107G   15G  96% /
tmpfs                    3.9G   15M  3.9G   1% /tmp
/dev/sda1                453M  179M  247M  42% /boot
tmpfs                    789M   20K  789M   1% /run/user/42
tmpfs                    789M   60K  789M   1% /run/user/1000
/dev/mapper/centos-home  100G   85G   16G  96% /mnt

Answer 1

This is working for me. You can also color the output if you want.

#! /bin/bash -
TXT_BLD=$(tput bold)
TXT_RST=$(tput sgr0)
IFS= mapfile -t disk < <(df -h | tail -n +2)
for line in "${disk[@]}"; do
    USAGE=$(echo $line | awk '{print $5/1}')
    if [[ "$USAGE" -gt '95' ]]; then
        echo "${TXT_BLD}$line${TXT_RST}"
    else
        echo "$line"
    fi
done

This will make the line yellow if greater than 85% and red if greater than 95%:

#! /bin/bash -
TXT_BLD=$(tput bold)
TXT_RED=$(tput setaf 1)
TXT_YLW=$(tput setaf 3)
TXT_WARN="${TXT_BLD}${TXT_YLW}"
TXT_ERR="${TXT_BLD}${TXT_RED}"
TXT_RST=$(tput sgr0)
IFS= mapfile -t disk < <(df -h | tail -n +2)
for line in "${disk[@]}"; do
    USAGE=$(echo $line | awk '{print $5/1}')
    if [[ "$USAGE" -gt '95' ]]; then
        echo "${TXT_ERR}$line${TXT_RST}"
    elif [[ "$USAGE" -gt '85' ]]; then
        echo "${TXT_WARN}$line${TXT_RST}"
    else
        echo "$line"
    fi
done