install.sh

#!/usr/bin/env sh
#

which_cmd() {
    which "${1}" 2>/dev/null || \
        command -v "${1}" 2>/dev/null
}

check_cmd() {
    which_cmd "${1}" >/dev/null 2>&1 && return 0
    return 1
}

curl="$(which_cmd curl)"
wget="$(which_cmd wget)"
bash="$(which_cmd bash)"
git="$(which_cmd git)"
smth="$(which_cmd pypy)"

SYSTEM="$(uname -s)"
OS="$(uname -o)"
MACHINE="$(uname -m)"

SOURCE_DST="/usr/src"

if [ -z "${BASH_VERSION}" ]
then
    # we don't run under bash
    if [ ! -z "${bash}" -a -x "${bash}" ]
    then
        BASH_MAJOR_VERSION=$(${bash} -c 'echo "${BASH_VERSINFO[0]}"')
    fi
else
    # we run under bash
    BASH_MAJOR_VERSION="${BASH_VERSINFO[0]}"
fi

HAS_BASH4=1
if [ -z "${BASH_MAJOR_VERSION}" ]
then
    echo >&2 "No BASH is available on this system"
    HAS_BASH4=0
elif [ $((BASH_MAJOR_VERSION)) -lt 4 ]
then
    echo >&2 "No BASH v4+ is available on this system (installed bash is v${BASH_MAJOR_VERSION}"
    HAS_BASH4=0
fi

if [ "${OS}" = "GNU/Linux" -o "${SYSTEM}" = "Linux" ]
then
    if [ "${HAS_BASH4}" = "1" ]
    then
        echo 'Bash is here!'
        if [ "$wget" = "" ] && [ "$curl" = "" ]
        then
            echo "Whoops... We can't find curl and wget on your system. Therefore we need to install this."
            exit 1
        else
            echo 'Ok. Something is here'
        fi
    else
        echo 'No bash in the system'
    fi
fi

echo 'Ok. Continue...'

# Check which package managers are available
apk=$(which apk 2>/dev/null || command -v apk 2>/dev/null)
apt_get=$(which apt-get 2>/dev/null || command -v apt-get 2>/dev/null)
dnf=$(which dnf 2>/dev/null || command -v dnf 2>/dev/null)
emerge=$(which emerge 2>/dev/null || command -v emerge 2>/dev/null)
equo=$(which equo 2>/dev/null || command -v equo 2>/dev/null)
pacman=$(which pacman 2>/dev/null || command -v pacman 2>/dev/null)
yum=$(which yum 2>/dev/null || command -v yum 2>/dev/null)
zypper=$(which zypper 2>/dev/null || command -v zypper 2>/dev/null)

package_manager() {
    [ -x "$(which $1)" ]
}

if package_manager apt-get; then
    echo "Whoa! apt-get is here!"
elif package_manager yum; then
    echo "Whoa! Yum is here!"
fi