nullshell
do nothing but print keep alive characters, can be used for login shell
This is a minimal program that does nothing but print some characters (namely version information and time&date string) every now and then. It is intended to be used for login shell with accounts accessible via secure shell that are used for secure tunneling but should not allow to execute commands.
Use at your own risk, pay attention to license and warranty, and disclaimer on external links!
Requirements
To compile and run nullshell you need:
- nothing (this is plain C)
- markdown ↗️ (HTML documentation)
Additionally it is expected to have make and a C compiler around to
successfully compile.
Build and install
Building and installing is very easy. Just run:
make
followed by:
make install
This will place an executable at /usr/bin/nullshell.
Usage
To create a new user user with nullshell as login shell just run:
useradd -s /usr/bin/nullshell user
Or to make nullshell the login shell for an existing user user:
usermod -s /usr/bin/nullshell user
Make sure /usr/bin/nullshell is listed in /etc/shells if your system
expects this.
License and warranty
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
Disclaimer on external links
Our website contains links to the websites of third parties ("external links"). As the content of these websites is not under our control, we cannot assume any liability for such external content. In all cases, the provider of information of the linked websites is liable for the content and accuracy of the information provided. At the point in time when the links were placed, no infringements of the law were recognisable to us. As soon as an infringement of the law becomes known to us, we will immediately remove the link in question.
💡️ Hint: All external links are marked with an arrow pointing diagonally in an up-right (or north-east) direction (↗️).
Upstream
URL: GitHub.com
Mirror: eworm.de GitLab.com