Shell

1: Bash
2: Powershell

1 - Bash

Here is an example of error handling:

some-executable  
if [[ $? -ne 0 ]] ; then
        echo "If we hit this block there was an error"
fi

This function can be used to determine the Operating System (atleast ones I care about):

setOs() {
    MY_OS=""

    case "$OSTYPE" in
        darwin*)  MY_OS="darwin" ;; 
        linux*)   MY_OS="linux" ;;
    esac

    if [[ "$MY_OS" -eq "linux" ]] && [[ -r /etc/debian_version ]] ; then
        MY_OS="debian"
    elif [[ "$MY_OS" -eq "linux" ]] && [[ -r /etc/fedora-release ]] ; then
        MY_OS="fedora"
    elif [[ "$MY_OS" -eq "linux" ]] && [[ -r /etc/oracle-release ]] ; then
        MY_OS="oel"
    elif [[ "$MY_OS" -eq "linux" ]] && [[ -r /etc/centos-release  ]] ; then
        MY_OS="centos"
    elif [[ "$MY_OS" -eq "linux" ]] && [[ -r /etc/redhat-release  ]] ; then
        MY_OS="rhel"
    elif [[ "$MY_OS" -ne "darwin" ]] ; then
        echo "Could not determine OS"
        exit 1
    fi
}

2 - Powershell

The variables $IsLinux , $IsWindows, & $IsMac can be used to determine OS