20 Jun 15

Yes, source executes script differently, I mean, in a different shell

Objective

See how differently shell script is executed using source.

1. Basic

source command executes the provided script (executable permission is not mandatory) in the current shell environment, while ./ executes the provided executable script in a new shell.

source command do have a synonym . filename.

To make it more clear, have a look at the following script, which sets the alias, using a shell script file named, make_alias.

2. make_alias file

#! /bin/bash
alias myproject='cd ~/Documents/Projects/2015/NewProject'

3. Two options

Now we have two choices to execute this script. But with only one option, the desired alias for your current shell can be created among these two options.

3.1. Option 1 ./make_alias

Make script executable first.

chmod +x make_alias

3.1.1. Execute

./make_alias

3.1.2. Verify

alias

3.1.3. Output

no alias for myproject

Whoops!, alias is gone with the new shell.

Now, let’s go with the second option.

3.2. Option 2 source make_alias

No need to make script executable while using source.

3.2.1. Execute

source make_alias

or

. make_alias

3.2.2. Verify

alias

3.2.3. Output

alias myproject='cd ~/Documents/Projects/2015/NewProject'

Yeah, alias is set now.

4. Reference

• My answer on SU