gksudo vs. sudo strangeness

CJS · 05-14-2008, 09:34 PM

How do you redirect the output of gksudo as the root user? For instance, "gksudo cmd > file1" outputs file1 under the original user, not root. Trying:

Code:

gksudo 'cmd > file1'

does not work at all. There are tricks with sudo that work, such as:

Code:

sudo bash -c 'cmd > file'

but:

Code:

gksudo bash -c 'cmd > file'

does not work. I also noticed that gksudo does not seem to output stderr; if you run "gksudo cmd" in the terminal window (and assuming cmd normally outputs to the terminal), then cmd will output stdout to the terminal but not stderr. This is unlike sudo which handles both stdout and stderr.

Unfortunately I can't just simply use sudo, because I'm using it in a bash script that will be run from a desktop shortcut--there is no terminal involved, so I need the graphical input of gksudo for accepting the password.

Any ideas of how to make gksudo work in this case? Any insight/help would be greatly appreciated.

jim mcnamara · 05-15-2008, 06:03 AM

Quote:

there is no terminal involved

stderr and stdout are terminal streams. GUI windows accept messages from user input devices, not stdin.

You've kind of answered your own question here.

CJS · 05-15-2008, 08:07 AM

Quote:

Originally Posted by jim mcnamara

stderr and stdout are terminal streams. GUI windows accept messages from user input devices, not stdin.

You've kind of answered your own question here.

OK, fair enough, but I think that still leaves me with my main question--is there any way to run commands (that use stdin and stderr) in scripts as root, and redirect their output as root, while running the script from a desktop shortcut? If I use sudo that obviously doesn't work because I have no chance to input a password. I could make the script call up a terminal to ask for the password, but I would much rather have the nice GUI input of gksudo. So is it simply not possible to do with gksudo?

matthewg42 · 05-15-2008, 08:28 AM

You could do the re-direction inside a script. e.g.

Code:

#!/bin/bash
some_command | tee /some/log/file

(tee outputs to standard output and the log file. Add the -a option to append to the log file, rather than overwriting it.)

Call that script with gksudo.

CJS · 05-15-2008, 06:29 PM

Quote:

Originally Posted by matthewg42

You could do the re-direction inside a script. e.g.

Code:

#!/bin/bash
some_command | tee /some/log/file

(tee outputs to standard output and the log file. Add the -a option to append to the log file, rather than overwriting it.)

Call that script with gksudo.

Yes, I think that's a great way to do it if one doesn't mind running the whole script as root. I also figured out at least one solution to my original problem of running single commands, and their redirections, as root in a script (while using the GUI password input of gksudo):

Code:

#!/bin/bash
gksudo true
sudo bash -c 'cmd > file'

Basically, just run gksudo with some placeholder command like "true", which then allows the gksudo GUI to handle getting the password to run as root, and then sudo actually gets the job done since the password has all ready been entered.

matthewg42 · 05-15-2008, 06:47 PM

Then I think you need to patch gksudo to pipe output to stdout (if it has a tty), or request such a feature from the gksudo team.