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Nix Package Index Says 'nix-shell : try package.done, undo changes made?'
When working with Nix, you might encounter a situation where you've made changes within a nix-shell environment and want to undo them. This article will guide you through the process of undoing changes made in a nix-shell environment using the nix-shell command.
Understanding Nix and nix-shell
Nix is a package manager for Linux and other Unix systems. It allows you to manage your system's software dependencies declaratively. nix-shell is a command provided by Nix that creates a shell environment with the specified packages.
The Issue
Suppose you've created a nix-shell environment for a specific package and made some changes within it. Later, you might want to undo these changes or revert to the original state of the package. In such cases, you can use the nix-shell command with the try and done options.
Using nix-shell try package.done
The nix-shell try package.done command creates a new shell environment with the specified package and runs the commands within it. Once the commands are executed, the shell environment is destroyed, and you're returned to your original shell. This command is useful when you want to test a package or a set of commands without making permanent changes to your system.
If you've made changes within the nix-shell environment and want to undo them, you can use the nix-shell try package.done command again. This command will create a new shell environment with the original package, ignoring any changes made in the previous environment.
Example
Let's consider an example where you've created a nix-shell environment for the hello package and made some changes within it:
$ nix-shell -p hello
...
$ echo "Hello, world!" > hello.txt
...
Now, if you want to undo the changes made to the hello.txt file, you can use the nix-shell try hello.done command:
$ nix-shell try hello.done
...
$ rm hello.txt
...
In this example, the nix-shell try hello.done command creates a new shell environment with the original hello package, ignoring the hello.txt file created in the previous environment.
References
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