Mini Shell

#!/usr/bin/bash


function createHookHeader(){
    local hook_file="$1"
    local notificator="$2"
    local common_path="$3"

    if [ ! -e "${common_path}/tmp" ]; then
        mkdir -p "${common_path}/tmp"
    fi
    if [ ! -e "${hook_file}" ]; then
        echo "#!/bin/bash" > "${hook_file}"
        chmod 755 "${hook_file}"
    else
        chmod 755 "${hook_file}"
        tmp=`/bin/sed -n '/#\!\/bin\/\(ba\)\?sh/p' "${hook_file}"`
        if [ -z "${tmp}" ];then
            /bin/grep -q "${hook_file}.${notificator}.bak" "${hook_file}"
            if [ $? -eq 1 ];then
                mv -f "${hook_file}" "${hook_file}.${notificator}.bak"
                echo "#!/bin/bash" > "${hook_file}"
                echo "${hook_file}.${notificator}.bak"' "$@"' >> "${hook_file}"
                chmod 755 "${hook_file}" "${hook_file}.${notificator}.bak"
            fi
        fi
    fi
}

function checkHookString(){
    local hook_file="$1"
    local pattern="$2"
    local comment="$3"

    if [ -e "${hook_file}" ];then
        tmp=`cat "${hook_file}" | grep "${pattern}"`
        if [ -z "${tmp}" ];then
            echo "${pattern}   #${comment}" >> ${hook_file}
        fi
    fi
}

function removeEmptyStringsFromFile(){
    local hook_file="$1"

    res=`sed -e '/^$/d' "${hook_file}"`
    echo "${res}" > "${hook_file}"
}

if [ ! -e "/usr/local/cpanel/cpanel" ]; then
    exit 0
fi

POSTUPCP="/scripts/postupcp"
TARGET="cloudlinux-linksafe"
COMMON_PATH="/usr/share/${TARGET}/cpanel/hooks"
POSTUPCP_HOOK="${COMMON_PATH}/cloudlinux_linksafe_hook.sh"

createHookHeader "${POSTUPCP}" "${TARGET}" "${COMMON_PATH}"
checkHookString "${POSTUPCP}" "${POSTUPCP_HOOK}" "${TARGET}"
removeEmptyStringsFromFile "${POSTUPCP}"
# Versions before 1.1-17 have bug: script `postupcp` in some cases has wrong line due to bug that was fixed in AL-1689.
# Line `/scripts/postupcp` leads to recursion and hang.
# The wrong line from script `postupcp` is being removed by the following code line. DON'T REMOVE IT
# Task AL-2208 reintroduced the bug
sed -i '/\/scripts\/postupcp/d' "${POSTUPCP}"
"${POSTUPCP_HOOK}"