How do I use source command under UNIX / Linux / BSD / OS X operating systems?

The source command in shell is used to execute commands from a file in the current shell. This is useful to load function or variables stored in another file.

source command syntax

The syntax is as follows:

source filename
source /path/to/file

It will read and execute commands from given FILENAME in the current shell. The entries in $PATH are used to find the directory containing FILENAME.

source command Examples

Create a function file called functions.sh as follows:

hello(){
  echo "I'm hello()"
}    
getos(){
  echo "OS is - $(uname)"
}

Create a shell script called test.sh as follows

#!/bin/bash
source functions.sh
# call hello function
hello
# call getos function
getos

Save and close the file. Run it as follows:
chmod +x test.sh
./test.sh

See also:

• Writing your first shell function