`source ~/.bash_profile` do not works inside a bash script

Question

This is a script that move a bash file into homepage and load it with source command.

# update.sh
#!/bin/bash
cp -f $PWD/bash_profile ~/.bash_profile
source ~/.bash_profile

It does not work! It update file with cp -f $PWD/bash_profile ~/.bash_profile.

Inside ~/.bash_profile there is a new PS1 definition. File is updated but no changes happened until new window is opened. I need to run source ~/.bash_profile after script execution ...

Is it possibile to run source command inside bash script?

Answer 1

From MangeshBiradar here:

Execute Shell Script Using . ./ (dot space dot slash)

While executing the shell script using “dot space dot slash”, as shown below, it will execute the script in the current shell without forking a sub shell.

$ . ./setup.bash

In other words, this executes the commands specified in the setup.bash in the current shell, and prepares the environment for you.

Answer 2

The bash script runs in its own instance of the shell. When the shell exits, all environment variables of that new shell (including your PS1) are forgotten. Note: this is a security consideration -- if a shell could change the environment of it's caller, it could very easily do some serious damage to that user by aliasing various commonly used commands.

If you run source update.sh though, it will run the commands as if the user typed them in on their own. (or you could do as @JonathanMay suggested using the ., which does the same thing).