source Command in Linux

Syntax of source Command in Linux

The basic syntax of the source command in Linux is as follows:

Where:

• source: This is the command itself that tells the shell to read and execute commands from a file.
• filename: This is the name of the file from which commands are read and executed.

Options in source Command in Linux

Example Usages

• Setting Environment Variables:

  Output:

  Explanation: In this example, we are creating a file named 'testfile' and adding an environment variable 'VAR' to it. We then use the source command to load the variables from 'testfile' into the current shell. Finally, we print the value of 'VAR' which outputs 'Hello World'.

• Adding a Path to PATH Variable:

  Output:

  Explanation: This example demonstrates how to add a new path to the PATH variable. We create a file 'pathfile' and add a new path to the PATH variable. After sourcing 'pathfile', the new path is added to the PATH variable of the current shell.

Advanced Use Cases of source Command in Linux

• Running a Script in the Current Shell:

  Output:

  Explanation: This example demonstrates how to run a script in the current shell. We create a script 'script.sh' and give it execute permissions. When we source 'script.sh', it runs in the current shell and prints 'Hello from script'.

• Sourcing a Script with Arguments:

  Output:

  Explanation: In this example, we create a script 'greet.sh' that takes one argument. When we source 'greet.sh' with the argument 'World', it prints 'Hello World'.

• Sourcing a Script from a Different Directory:

  Output:

  Explanation: In this example, we demonstrate how to source a script from a different directory. We create a directory 'myscripts', create a script 'myscript.sh' in that directory, and give it execute permissions. When we source 'myscript.sh' from the 'myscripts' directory, it runs in the current shell and prints 'Hello from script in another directory'.