Removing npm tmp after install

npm-tmp-clean.sh

#!/usr/bin/env bash

# this is pid of the bash we are in
bash_pid=$$
bash_pid=$(echo -e ${bash_pid} | tr -d '[[:space:]]');

# this is shell of the bash
shell_pid=$(ps -p ${bash_pid} -o ppid=;)
shell_pid=$(echo -e ${shell_pid} | tr -d '[[:space:]]');

# this is the npm who runs shell
npm_pid=$(ps -p ${shell_pid} -o ppid=;)
npm_pid=$(echo -e ${npm_pid} | tr -d '[[:space:]]');

# test whether npm tmp configuration is set
# if not, assume the default /tmp
if [ -z ${npm_config_tmp} ]; then 
	  npm_config_tmp=/tmp
fi;

echo "Removing ${npm_config_tmp}/npm-${npm_pid}*";
rm -rf "${npm_config_tmp}"/npm-${npm_pid}*

package.json

{
    "scripts": {
        "postinstall": "./bin/npm-tmp-clean.sh"
    }
}