I have a shell script with the following contents. I call it with ./script.sh. Echo successfully runs, but not when I try to save its output to a variable. The same is true for all commands I've tested so far; ls, pwd, node, etc…
#!/bin/zsh
echo foo
# foo
output=$("echo foo")
# command not found: echo foo
How come?
EDIT: Fix: the last echo is inside a string!
It seems like you found the issue. You should quote only the string passed to echo and not the entire command itself:
output=$("echo foo")
Should instead be:
output=$(echo "foo")
If you want the output variable to contain the literal string echo foo then you should just set it as:
output='echo foo'
but could also do:
output=$(echo 'echo foo')
node, which was my initial goal, calling a node-script. I get command not found: node despite node being inside my $PATH variable. Which I checked by echoing path from inside the script. Thoughts?
node script.js succeeds, output=$(node script.js) fails. Falls perfectly in line with the question title, actually.
As one might expect commands inside parentheses creates a subshell. But $() is not what you might think. It does not return the output of a command as a string it substitutes the output of a command into the shell. If you want proof try this: $(echo "echo 123")
Instead you want to use double quotes to capture it into a string instead of the array (the output split by spaces) being run on the shell.
output="$(echo foo)"
Note this isn't an issue specific to zsh it applies to bash as well.
echo foolike:output=$('echo foo'). Or if I escape the space likeoutput=$(echo\ foo)."echo foo"would result in a similar error; what's your goal?