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Introduction

The setenv command in Linux can be used for setting environment variables by giving them names and values. It is a built-in command for the C Shell, and its forks. It is similar to the export command found in other POSIX shells, having a slight difference in the syntax of the variable declaration.

Some users seemed to have faced issues while trying to run the command, annoyed by the following error message:

$ setenv: command not found

The fix to this, however, is quite simple. So if you’re stuck trying to run the command, you’d definitely want to figure out what you might be doing!


Install the tcsh shell

Why? because setenv is a built-in command for the C Shell (csh), so in order to be able to use the setenv command, you need to install the csh shell. In order to install the shell in your Linux machine, you need to use your system’s package manager, which will differ based on the distribution you are using. The former csh package is no longer found in most repositories, so you will need to install tcsh instead, which is an enhanced version of csh with better support. The commands required to install tcsh in the most commonly used Linux distributions are listed below:

Arch Linux

$ sudo pacman -Syu tcsh

Ubuntu

$ sudo apt-get update
$ sudo apt-get install tcsh

Debian

$ sudo apt-get update
$ sudo apt-get install tcsh

Fedora

$ sudo yum makecache
$ sudo yum install tcsh

RedHat

$ sudo dnf makecache
$ sudo dnf install tcsh

CentOS

$ sudo dnf makecache
$ sudo dnf install tcsh

In all the other distributions other than in Arch Linux, the first line of command is also quite important. The first line of command updates the repositories, keyrings and all, while the second line actually installs the package. If you don’t update your repository often before installing packages, it will become outdated and your installation commands may not work. Which is why you need to run this command first before installing the actual package. 

It’s the same in Arch Linux as well. That is, you need to update its repositories. But why we didn’t need 2 lines of command for that is because the “yu” after “-S” is responsible for updating the repositories right before installing the package, lessening the hassle of tying out two separate lines. You can write out the commands in other package managers within a single line too, by including a && between the commands.


Install tcsh from source code

If you’re unable to install tcsh using a package manager, and in case your repository does not have the tcsh package either, you can take the longer, harder route to installing it, which is to build and install it from the source code. Before all, you’d want to visit the following website and download a tarball of the latest version available for tcsh:

https://astron.com/pub/tcsh/

The most recent version I see is v6.24.00, so I’m going to download it directly by using the following link:

https://astron.com/pub/tcsh/tcsh-6.24.00.tar.gz

Once downloaded, navigate to the directory where you downloaded the tarball and extract it using the tar command:

$ tar -xf tcsh-6.24.00.tar.gz

Now enter the directory that got extracted by using the cd command:

$ cd tcsh-6.24.00

Inside this directory, you should be seeing a whole lot of files and scripts, but of all, you need to run the configure shell script. Do so by executing:

$ ./configure

This will create all the configuration files necessary for building the package. Once the files are created, you can now run make to build the package:

$ make

Lastly, install the package systemwide, by running:

$ sudo make install

You should now be able to start the tcsh shell, and use the setenv command from inside of it.


Change current shell to tcsh

Once you’re done installing the tcsh shell, you first need to switch to that shell from your current one to run the setenv command. Don’t expect the command to run in your existing shell (which is probably the Bourne Again Shell or ZSH), right after having tcsh installed. 

In order to switch shells in Linux, you can either use the preferences menu of your terminal (if it has one), or you can also use the chsh command. To switch from your current shell to the tcsh shell, use the following command:

$ chsh -s /bin/tcsh

You should now hopefully be able to use and run the setenv command in your Linux terminal.


Alternative to the setenv command

Setenv is not the only command to achieve the thing you need. It essentially sets up environment variables for your system. And for that task, a more commonly used command is the export command, found in POSIX based shells. It is probably already available in your current shell. Why not give it a try?