Remove your old kernels on Fedora

rmOldKernels.sh

#!/bin/bash

UNAME=$(uname -r)
CUR=($(echo "$UNAME" | awk -F'[.-]' '{print $1 $2 $3 $4}'))
CUR_1=($(echo "$UNAME" | awk -F'[.-]' '{print $1}'))
CUR_2=($(echo "$UNAME" | awk -F'[.-]' '{print $2}'))
CUR_3=($(echo "$UNAME" | awk -F'[.-]' '{print $3}'))
CUR_V=($(echo "$UNAME" | awk -F'[.-]' '{print $4}'))
FOUND=0

function add_to_list {
    DEV=$(echo $I | sed s/core/devel/)
    if rpm --quiet -q ${DEV}; then
        LIST+=($DEV)
    fi
    LIST+=($I)
    FOUND=1
}

function compare {
    if (( "$1" > "$2" )); then continue
    elif (( "$1" < "$2" )); then
        add_to_list
        continue
    fi
}

for I in $(rpm -q kernel-core); do
    THIS=($(echo "$I" | awk -F'[.-]' '{print $3 $4 $5 $6}'))

    if [[ "${THIS}" == "${CUR}" ]]; then
        continue
    fi

    THIS_1=($(echo "$I" | awk -F'[.-]' '{print $3}'))
    THIS_2=($(echo "$I" | awk -F'[.-]' '{print $4}'))
    THIS_3=($(echo "$I" | awk -F'[.-]' '{print $5}'))
    THIS_V=($(echo "$I" | awk -F'[.-]' '{print $6}'))

    compare "${THIS_1}" "${CUR_1}"
    compare "${THIS_2}" "${CUR_2}"
    compare "${THIS_3}" "${CUR_3}"
    compare "${THIS_V}" "${CUR_V}"
done

if ((FOUND)); then
    echo "Currently running kernel-$UNAME"
    dnf remove "${LIST[@]}"
fi