BeagleBone command works as root but not with sudo

Hi Jan,

The problem is that even though you run echo with sudo   the output is redirected by your command shell which hasn't got the privileges.

one way around this would be :

sudo sh -c "echo out > /sys/class/gpio/gpio49/direction"

hope that makes sense.

Brian

Yes!! that's it. So I was running the echo as root, but accessed the file as "myself", right?

or in my case, where I use bash?

sudo /bin/bash -c "echo out > /sys/class/gpio/gpio49/direction"

If my understanding is correct, the shell environment (sh) needed to be elevated so that the echo command is run within it, because otherwise the redirected output would go via the user (debian) shell which doesn't have privileges to access the destination location, because of how the shell environment works.

So it's as though you needed to elevate the privileges of the standard input/output of the environment so it had permissions to be passed to the destination, because even though echo itself was elevated, the environment wasn't until sh was ran with sudo.

Christopher Stanton wrote:

 

If my understanding is correct, the shell environment (sh) needed to be elevated so that the echo command is run within it, because otherwise the redirected output would go via the user (debian) shell which doesn't have privileges to access the destination location, because of how the shell environment works.

 

So it's as though you needed to elevate the privileges of the standard input/output of the environment so it had permissions to be passed to the destination, because even though echo itself was elevated, the environment wasn't until sh was ran with sudo.

yes exactly.

Jan Cumps - bash or sh - it doesn't matter.  Any command is elevated to user id 0 with sudo.  The redirect has to be part of the command (hence, -c ".....") as opposed to being "owned" by sudo which was executed by an ordinary user.

By the way, if you are going to execute several root commands, just do

     sudo -i

once before all of the commands.  For example,

     sudo -i

     apt update > log

     apt dist-upgrade >> log

     apt autoclean >> log

Added benefit: No worries about the redirection belonging to the root or the ordinary user who invoked sudo.