Assign output to variable for command run under different user on OSX

Question

I run a bash python command as current user, by doing this:

su $USER -c 'python3 -m site --user-site'

This works properly and prints the following:

/Users/standarduser7/Library/Python/3.6/lib/python/site-packages

I want to assign this output to a variable, so I'm using "$(command)":

target="$(su $USER -c 'python3 -m site --user-site')"

At this point, the OSX terminal hangs and has to be killed. Using backticks instead of "$(command)" leads to same result.

However, if I run the command without user, everything works as it should: target="$(python3 -m site --user-site)" echo target

output: /Users/standarduser7/Library/Python/3.6/lib/python/site-packages

How can I assign the output from a command run as the current user to a variable?

CJK · Accepted Answer · 2018-02-06 16:44:28Z

0

I don’t think it’s hanging; I think it’s showing a blank (prompt-less) command-line and is waiting for input. When I key in the user password, it returns this result:

Password:/Users/CK/Library/Python/2.7/lib/python/site-packages

and this is what ends up being stored in the target variable. A quick parameter substitution can rectify this anomalous output:

target=${target#*:}

The other solution (credit given to this answer) is to create a file descriptor as a copy of stdout, then tee the command to the copy, which then allows stdout to be piped to grep in order to process the output:

exec 3>&1 # create a copy of stdout

target=$(su $USER -c "python -m site --user-site" | tee /dev/fd/3 | grep -o '\/.*')

exec 3>&- # close copy

answered Feb 6, 2018 at 16:44

CJK

6,1421 gold badge10 silver badges27 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Assign output to variable for command run under different user on OSX

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related