SoGeeky SoGeeky - 11 months ago 69
Linux Question

How do I broadcast messages to all bash terminal in python using wall command with stdin?

I wanted to broadcast message to all the bash terminal on my raspbian.

I understand that there's wall command to perform the step and I could use os.system python module to execute the command.

However, running the command "wall text.txt" requires sudo privilege. Is there any way to use wall command with stdin from python?

Answer Source

It is indeed required to be a superuser to run wall with an input file, man says:

     wall - write a message to users

     wall [file]

     Wall displays the contents of file or, by default, its standard input, on the terminals of all currently logged in users.

     Only the super-user can write on the terminals of users who have chosen to deny messages or are using a program which automatically denies messages.

     Reading from a file is refused when the invoker is not superuser and the program is suid or sgid.

But you can do this:

$ echo hello hello >text.txt
$ python                    
Python 2.7.1 (r271:86832, Mar 18 2011, 09:09:48) 
[GCC 4.5.0 20100604 [gcc-4_5-branch revision 160292]] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> os.system('cat text.txt | wall')

Broadcast Message from mak@vader                                             
        (/dev/pts/14) at 10:31 ...                                             

hello hello                                                                    

Broadcast Message from mak@vader                                            
        (/dev/pts/14) at 10:31 ...                                             

hello hello