Description: The ‘export’ command in Unix-like operating systems, including Linux and macOS, is a fundamental tool for setting environment variables that can be used by child processes. When a variable is defined in a shell, it is only available in the context of that current shell. However, by using ‘export’, this variable can be made available to any process that is started from that shell, thus allowing for greater flexibility and control over the execution environment. This command is essential for configuring various environments, as it allows users to define specific configurations that may be required by applications and scripts. Additionally, ‘export’ can be used to modify existing environment variables, facilitating the customization of application behavior. In summary, ‘export’ is a key command in managing environments in Unix-like systems, providing an efficient way to manage the visibility and scope of variables within the terminal session and beyond.
History: The ‘export’ command was introduced in the context of Unix systems in the 1970s, as part of the evolution of Unix shells. As Unix operating systems developed, the need to manage environment variables more effectively became apparent, leading to the creation of this command. Over time, ‘export’ has become a standard in various shells, including Bash, which is one of the most widely used today.
Uses: The ‘export’ command is primarily used to define and modify environment variables in terminal sessions. This is especially useful in shell scripts, where certain configurations need to be available to child processes. It is also used in setting up development environments, allowing developers to set variables that affect the behavior of the applications they are running.
Examples: A practical example of using ‘export’ is as follows: if you want to set an environment variable called ‘MY_VAR’ with the value ‘Hello’, you can do this by executing ‘export MY_VAR=Hello’. Then, any child process started from that shell will be able to access ‘MY_VAR’. Another example would be modifying the ‘PATH’ variable to include a new directory: ‘export PATH=$PATH:/new/directory’.
