Using sudo with for loop

Question

I want to run a simple for loop command with sudo, but it isn't working:

sudo -i -u user for i in /dir; do echo $i; done

I get the following error:

-bash: syntax error near unexpected token `do'

Probably a very simple thing I am overlooking. Any help?

Answer 1

sudo wants a program (+arguments) as a parameter, not a piece of shell script. You can do this, though:

sudo -i -u user sh -c 'for i in /dir; do echo $i; done'

Note the single quotes. If you used double quotes, your shell would try to expand the $i before sudo (or, rather, the shell run by it) ever sees it.

PS. a separate problem, as pointed out in a comment (only six years later), is that if you want to iterate over the files in a directory, the proper syntax is for i in /dir/*. for accepts a list, and /dir is a list... with one item. /dir/* expands to a list of files in /dir due to wildcard expansion.

Answer 2

You can try sudo bash -c 'commands here'

Answer 3

Put the sudo inside the loop:

for i in /dir; do
    sudo -u user somecommand $i
done

This won't work without extra steps if you need the other user's permissions to generate the glob for the loop, for example.