Export is defined in POSIX as The shell shall give the export attribute to the variables corresponding to the specified names, which shall cause them to be in the environment of subsequently executed commands. If the name of a variable is followed by = word, then the value of that variable shall be set to the word.
How does export command work?
The export command is fairly simple to use as it has straightforward syntax with only three available command options. In general, the export command marks an environment variable to be exported with any newly forked child processes and thus it allows a child process to inherit all marked variables.
What does export do in Shell?
Export is a built-in command of the Bash shell. It is used to mark variables and functions to be passed to child processes. Basically, a variable will be included in child process environments without affecting other environments.
Is export command permanent?
When an environment variable is set from the shell using the export command, its existence ends when the user’s sessions ends. This is problematic when we need the variable to persist across sessions. To make an environment persistent for a user’s environment, we export the variable from the user’s profile script.
How do I export a variable in shell?
Exporting shell variables (export shell command)
You can use the export command to make local variables global. To make your local shell variables global automatically, export them in your . profile file. Note: Variables can be exported down to child shells but not exported up to parent shells.
Why do we need to export variables in shell?
14 Answers. export makes the variable available to sub-processes. means that the variable name is available to any process you run from that shell process. If you want a process to make use of this variable, use export , and run the process from that shell.
Where does Linux export to?
You can add it to your shell configuration file, e.g. $HOME/. bashrc or more globally in /etc/environment . After adding these lines the changes won’t reflect instantly in GUI based system’s you have to exit the terminal or create a new one and in server logout the session and login to reflect these changes.
How do I export a variable in bash?
Export Variables
- vech=Bus. Display the value of a variable with echo, enter:
- echo “$vech” Now, start a new shell instance, enter:
- bash. Now, display back the value of a variable vech with echo, enter:
- echo $vech. …
- export backup=”/nas10/mysql” echo “Backup dir $backup” bash echo “Backup dir $backup” …
- export -p.
How do you set a variable in Linux terminal?
You can set your own variables at the command line per session, or make them permanent by placing them into the ~/. bashrc file, ~/. profile , or whichever startup file you use for your default shell. On the command line, enter your environment variable and its value as you did earlier when changing the PATH variable.