`setx` equivalent in Ubuntu

Solution 1:

You can do this simply by declaring it as new in the command line or re-declaring it. For example, if you want to add ~/testfolder to your path variable, you simply can enter it in your current terminal (this is just an example):

PATH="$HOME/testfolder:$PATH"

This will of course only change it for the time you have said terminal session open. Notice the $ usage here, you leave it out for declaration, but if you want to display it you need to add $ to expand its contents.

If you want to declare them more lasting and general you can add them into your ~/.bashrc (only for you) file or in /etc/bash.bashrc (system wide) for example if you want them to be counting for only you or for all users. Another option is to add it to your .profile file (only for yourself) where it will be viable from the moment you log in. You can do this with echo for example if you're sure this variable is not set already or if you create new ones (only an example):

echo "variable=value" >> /path/filename

If you however want to edit a file outside your user directory which is the case when you want to edit /etc/bash.bashrc you need to use sudo and so you cant simply use a 'here document' since this would not work, instead use then a line like below:

echo "variable=value" | sudo tee -a /path/filename

If the variable however already exists you can change it with the sed command (also only an example):

sed -i.bak 's/variable=value/variable=new-value/' /path/filename

This will edit the variable in file but create a backup of it prior to the edit. If you change files outside your user directory with sed you need to use sudo in most cases so the line would be:

sudo sed -i.bak 's/variable=value/variable=new-value/' /path/filename

Removing a variable from a file can be done with sed as well, just leave the second part of the regex empty:

sed -i.bak 's/variable=value//' /path/filename

If your interested which environment variables are set you can use the env command to list them, ( set -o posix ; set ) | less or sh -c set. All three give various amounts of output, with ( set -o posix ; set ) | less giving back the most variables which are actually set.

Solution 2:

There is no direct equivalent of setx /m, but there are ways to accomplish what setx /m does.

setx /m puts variable=value in HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Environment. Non-/m (i.e. per-user) setx simply puts the variable=value in HKCU\Environment.

You specifically asked for 'system wide'. For that, you would add the variable-value pair to either /etc/environment OR to /etc/profile.d/<yourfile>. The former is evaluated by pam, while the latter is evaluated by /bin/sh. Thus, in /etc/profile.d/<yourfile>, you would add variable=value; export variable. (bash also allows export variable=value). For /etc/environment you would add variable=value.

The per-user equivalents are ~/.pam_environment and ~/.profile.

See also: https://help.ubuntu.com/community/EnvironmentVariables

Solution 3:

You can export environment variables on command line, but it won't affect the effective environment in already started processes, only in the current process and its subprocesses. So in practice you often need to relogin when changing environment variables.