Fish Shell: How to set multiple environment variables from a file using export

Question

Is it possible to set environment variables with export in Fish Shell? I am working on a project that configures variables this way and it does not make sense to maintain a separate configuration file just for fish.

Consider this example in bash:

echo -e "foo=1\nfoobar=2\n" > foo; export $(cat foo | xargs); env | grep foo

   foo=1
   foobar=2

In fish shell, it appears that it will only set a single variable, and only if there is one variable in the file:

~ $ echo -e "foo=3\nfoobar=4" > foo; export (cat foo | xargs); env | grep foo

~ $ echo -e "foo=3" > foo; export (cat foo | xargs); env | grep foo

   foo=3

Is this just a flaw / omission in the Fish implementation of export?

This question is similar to but different from these other two posts:

• Share environment variables between bash and fish
• how to set and use multiple parameters in single environmental variable in fish shell

Answer 1

Your example almost works perfectly - it's not export that's the problem, but the use of xargs.

Try:

echo -e "foo=3\nfoobar=4" > .env; export (cat .env);  env | grep foo

The reason is that a command substitution separates arguments on newlines, and xargs removes them:

> count (cat .env | xargs)
1
> count (cat .env)
2

Answer 2

In fish, I'd expect you to get an error for export:

$ echo -e "foo=1\nfoobar=2\n" > foo; export (cat foo | xargs);  env | grep foo
bash: --: command not found...
fish: echo -e "foo=1\nfoobar=2\n" > foo; export (cat foo | xargs);  env | grep foo
                                         ^

If you have a file with variable=value lines and you want to use that to set environment variables:

$ cat foo
foo=1
foobar=2

$ source (sed -rn 's/^([^=]+)=(.*)/set -x \1 \2/p' foo | psub)
$ set -x | grep foo
foo 1
foobar 2