error while installing go from source

i am trying to install go from source

i follow this steps

git clone https://go.googlesource.com/go
cd go
git checkout go1.6.1

cd src
./all.bash

now it gives me the error saying

##### Building Go bootstrap tool.
cmd/dist
ERROR: Cannot find /root/go1.4/bin/go.
Set $GOROOT_BOOTSTRAP to a working Go tree >= Go 1.4.

any idea how can i fix this do i just need to set env variable or any other installation is needed ?

You need to have an installed Go version 1.4 or newer to build the recent Go releases. The build script defaults to some path but if it's not there you need to set GOROOT_BOOTSTRAP environment variable to point to a previous working Go installation.

Go is written in Go (starting from version 1.5) so you have to install Go1.4 first. Just get Go Version Manager and run:

$ gvm install go1.4 
$ gvm use go1.4 
$ export GOROOT_BOOTSTRAP=$GOROOT

Another approach is about to install gcc go frontend:

$ sudo apt-get install gccgo-5
$ sudo update-alternatives --set go /usr/bin/go-5
$ export GOROOT_BOOTSTRAP=/usr

If you are not using gvm and are on Linux, your go binary is mostly installed at /usr/local/go/bin/go. You need to set /usr/local/go as your GOROOT_BOOTSTRAP by:

$ export GOROOT_BOOTSTRAP=/usr/local/go

The following won't work if you haven't previously built from source (the version parsing will fail). Unfortunately it also won't work for windows (unless you're in wsl/cygwin/msys et cetera).
If you have the source for an older version you may want to use the following zsh/bash(?) function

# create a backup of a directory by recursively copying its contents into an empty one with a similar name
bckp () {
    old=$1 
    if [[ -z $1 ]]; then
        old="../$(basename "$(pwd)")" 
    fi
    new="$old-bckp" 
    [[ -d $new ]] && echo "already exists" && return 1
    cp -rf "$old/" "$new"
}

then do one, or some combination, of the following

if you have unstashed changes you want to commit:

cd $(go env GOROOT)                              # visit the root directory of your current go installation
bckp                                             # back it up
git stash                                        # keep any changes you've made but do not want to commit in a safe place
git pull                                         # collect remote commits
git stash pop                                    # restore your changes
cd src                                           # go to the golang source files and installation scripts
export GOROOT_BOOTSTRAP=$(go env GOROOT)-bckp    # make the environment variable accessible from other shells
chmod +x ./all.bash                              # set the permissions of the installation/build script so that it can be executed
./all.bash                                       # execute the installation/build script
cd ../bin && sudo ln -f $PWD/go /usr/bin/go      # create a globablly accessible link to the new binary, feels like it should be unnecessary but I couldn't use the new binary until I did this

or, if you've already pulled the commits you wish to include and popped your changes:

cd $(go env GOROOT)                                      # visit the root directory of your current go installation
bckp                                                     # back it up
cd ../go-bckp                                            # enter the backup directory
git stash                                                # keep any changes you've made but do not want to commit in a safe place
git checkout $(go version | cut -d- -f2 | cut -d" " -f1) # parse version info and restore the old codebase
git stash pop                                            # restore your changes
cd ../go/src                                             # go to the golang source files and installation scripts
export GOROOT_BOOTSTRAP=$(go env GOROOT)-bckp            # make the environment variable accessible from other shells
chmod +x ./all.bash                                      # set the permissions of the installation/build script so that it can be executed
./all.bash                                               # execute the installation/build script
cd ../bin && sudo ln -f $PWD/go /usr/bin/go              # create a globablly accessible link to the new binary, feels like it should be unnecessary but I couldn't use the new binary until I did this

or if you haven't made any changes:

cd $(go env GOROOT)                             # visit the root directory of your current go installation
bckp                                            # back it up
cd src                                          # go to the golang source files and installation scripts
export GOROOT_BOOTSTRAP=$(go env GOROOT)-bckp   # make the environment variable accessible from other shells
chmod +x ./all.bash                             # set the permissions of the installation/build script so that it can be executed
./all.bash                                      # execute the installation/build script
cd ../bin && sudo ln -f $PWD/go /usr/bin/go     # create a globablly accessible link to the new binary, feels like it should be unnecessary but I couldn't use the new binary until I did this.