golang

#!/bin/bash
##############################################################################
#
# golang
# -------------------
# Install or update Go language.
#
# Download Go source tarball and SHA1 hash from https://code.google.com. If 
# hashcheck is okay, install and setup Go in /usr/local/go, and modify the 
# system default $PATH to include it by appending to /etc/profile. 
#
# For x86_64 and 32-bit Linux, only. Should work on all distros, except for
# RHEL and CentOS.
#
# @author Isis Agora Lovecruft, 0x2cdb8b35
# @date  3 September 2012
# @version 0.0.4
#
##############################################################################

set -e

GO_VERSION="1.0.3"

function usage ()
{
    echo
    echo "$0 [options]"
    echo
    echo "install           Install Go ${GO_VERSION}"
    echo "reinstall         Update Go to ${GO_VERSION}"
    echo "path              Export PATH to Go & GoTools"
    echo
}

function install_go ()
{
    OUR_ARCH=$(uname -m)
    FILE="https://go.googlecode.com/files/go"
    DOWN="https://code.google.com/p/go/downloads/detail?name=go"
    if [[ "$OUR_ARCH" == "x86_64" ]]; then
        ARCH_STRING=".linux-amd64.tar.gz"
    elif [[ "$OUR_ARCH" == "i686" ]]; then
        ARCH_STRING=".linux-386.tar.gz"
    else
        echo "Unsupported architecture. Must be 64-bit or 32-bit."
        exit 1
    fi

    tarball=${FILE}${GO_VERSION}${ARCH_STRING}
    details=${DOWN}${GO_VERSION}${ARCH_STRING}

    GO_SOURCE=${HOME}/go${GO_VERSION}.tar.gz
    HTML_PAGE=${HOME}/go${GO_VERSION}.tar.gz.html

    if ! test -f "$GO_SOURCE" ; then
        if test -n "$tarball"; then
            echo "Getting GoTools from:
    ${tarball} "
            echo "Downloading GoTools, which includes gc (go compiler)..."
            wget --no-check-certificate -q -O $GO_SOURCE ${tarball}
        else
            echo "Error determining correct download...exiting..."
            exit 1
        fi
    else
        echo "We've already got the latest source code, using that..."
    fi

    if ! test -f "$HTML_PAGE" ; then
        echo "Getting reported SHA1 from:
    ${details} "
        wget --no-check-certificate -q -O $HTML_PAGE ${details}
        echo
    else
        echo "We've already got the reported SHA1 from code.google.com..."
        echo
    fi

    theirs=/tmp/go_reported_hash
    ours=/tmp/go_our_hash

    echo "Checking SHA1 hash of downloaded source..."
    grep "sha1" $HTML_PAGE | cut -d ">" -f 2 | cut -d "<" -f 1 | cat > $theirs
    sha1sum $GO_SOURCE | cut -d " " -f 1 > $ours

    echo "Reported SHA1 from Google Code: $(cat $theirs )"
    echo "Computed SHA1 from download:    $(cat $ours )"

    HASHDIFF=`diff ${theirs} ${ours}`
    if [[ "$HASHDIFF" == "" ]]; then
        echo
        echo "Installing GoTools ..."
        sudo tar -C /usr/local -xzf $GO_SOURCE && echo "Installation successful."
    else
        echo "WARNING: SHA1 sums do not match. Exiting..." & exit 1
    fi
}

function clean_up ()
{
    JUNK="$theirs $ours $HTML_PAGE $GO_SOURCE "
    echo
    echo "Cleaning up..."
    for file in $JUNK; do
        if test -f $file ; then
            echo "Removing ${file}..."
            sudo rm $file
        fi
    done
}

function export_paths ()
{
    if [ $(id -u) -eq 0 ]; then
        echo
        echo "Modifying system \$PATH to include Go..."
        sudo cat >> /etc/profile<<EOF
## Path to GoTools
export GOROOT=/usr/local/go
export PATH=$PATH:$GOROOT/bin
EOF
        echo "Successfully updated \$PATH in /etc/profile."
    else
        echo
        echo "Modifying user \$PATH..."
        sudo cat >> $HOME/.profile<<FIN
## Path to GoTools
export GOROOT=/usr/local/go
export PATH=$PATH:$GOROOT/bin
FIN
        echo "Successfully updated \$PATH in ${HOME}/.profile..."
    fi
}

function root_check ()
{
    if [ $(id -u) -ne 0 ]; then
        echo "Must be run as root."
        exit 1
    fi
}

function os_check ()
{
    if [ $(uname) != "Linux" ]; then
        echo "Sorry, this only works for Linux."
        exit 1
    fi
}

function go_check ()
{
    if test -n $(which go) ; then
        current=$(go version | cut -d " " -f 3 | cut -b 3- )
        echo "Found previous Go installation. Version: ${current} "
        if test -d /usr/local/go ; then
            if [[ "$current" == "${GO_VERSION}" ]] ; then
                echo "Already up to date!"
                exit 0
            elif [[ "$current" > "${GO_VERSION}" ]] ; then
                echo "Oops. You've got Go ${current}, while we've got Go ${GO_VERSION}."
                echo "Please mailto:isis@patternsinthevoid.net and tell Isis to update me."
                echo
            else
                echo "Updating previous Go installation to ${GO_VERSION}..."
            fi
        fi
    fi
}

function mercurial_check ()
{
    if test -z $(which hg) ; then
        echo "Go requires mercurial.Please use your distro's package manager 
to obtain it.
Exiting..."
    fi
}

if [[ "$#" == "0" ]]; then
    usage
    exit 1
else
    while [[ "x$1" != "x" ]]; do
        case $1 in
            install )
                root_check
                mercurial_check
                os_check
                go_check
                install_go
                clean_up
                export_paths
                echo
                echo "Installation successful!"
                echo
                echo "To get started learning go, try doing:"
                echo "    \$ go get code.google.com/p/go-tour/gotour "
                echo
                unset tarball
                unset details
                exit 0
                ;;
            reinstall )
                root_check
                mercurial_check
                os_check
                go_check
                install_go
                clean_up
                echo
                echo "Upgrade successful!"
                echo
                unset tarball
                unset details
                exit 0
                ;;
            path )
                os_check
                export_paths
                exit 0
                ;;
            * )
                usage
                ;;
        esac
    done
fi