$PATH what is it

 

PATH is an environmental variable in Linux and other Unix-like operating systems that tells the shell which directories to search for executable files (i.e., ready-to-run programs) in response to commands issued by a user. It increases both the convenience and the safety of such operating systems and is widely considered to be the single most important environmental variable. http://www.linfo.org/path_env_var.html For example, to add the directory /usr/sbin, the following would be used: PATH="/usr/sbin:$PATH" An alternative is to employ the export command, which is used to change aspects of the environment. Thus, the above absolute path could be added with the following two commands in sequence PATH=$PATH:/usr/sbin export PATH or its single-line equivalent export PATH=$PATH:/usr/sbin :  is the separator means the next path  https://stackoverflow.com/questions/35737627/what-does-the-colon-do-in-path echo $PATH will tell you what it is right now  On a default Ubuntu desktop install $PATH is: $ echo $PATH /usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games https://askubuntu.com/questions/386629/what-are-the-default-path-values It is set in .bash_profile for example  $PATH is the original path in the system # set PATH so it includes user's private bin if it exists if [ -d "$HOME/bin" ] ; then         PATH="$HOME/bin:$PATH" fi # set PATH so it includes user's private bin if it exists if [ -d "$HOME/.local/bin" ] ; then         PATH="$HOME/.local/bin:$PATH" fi export PATH="$PATH:/opt/mssql-tools/bin" # GO export GOROOT="/usr/local/go" export GOPATH="$HOME/goworkspace/project1" export PATH="$GOPATH/bin:$GOROOT/bin:$PATH"

if you type 

which bash

    /usr/bin/bash 

which php

    /usr/bin/php 

You will see bash (command line interpretor)  and php are installed in /usr/bin which is already included in default path