Red Hat

CODE="$(execute something)"
echo $CODE

# Just get the exit code
execute something
CODE=$?
echo $CODE

# ... or directly do something with it:
if execute something; then
    echo "it works"
else
    echo "did not work"
fi

# ... or for short, do something if it did work:
execute something && do this if the former command worked

# ... or for short, do something if it did NOT work:
execute something || do this if the former command failed

#!/bin/bash

function is_installed_rpm { rpm -qi "$(rpm -qp "$1" 2>/dev/null)" >/dev/null 2>&1; }
function install_rpm      { is_installed_rpm || rpm -Uhv "$1" ; }

install_rpm $RPM_FILE

function is_installed_rpm { rpm -qi "$(rpm -qp "$1" 2>/dev/null)" >/dev/null 2>&1; } 
function install_rpm      { is_installed_rpm "$1" || rpm -Uhv "$1" ; } 

# The following is an array of urls
PKG_URLS=( \
"https://....bla.rpm" \
"ftp://server.blub.com...rpm" \
)

for URL in "${PKG_URLS[@]}";do
        # rpm can install a package right from the url.
        install_rpm "$URL"
        failed
done

# yum does not care if a pkg is already installed, 
# so just install all in one command, even if all 
# pkgs are already installed, yum exits successfully.
#
# Maybe you have to split the yum-packages into two 
# steps, because you have to install the packages for
# repo-extension first before the other packages become
# available

YUM_PKGS="epel-release flash-plugin ...."

yum install $YUM_PACKAGES
failed