Hello Linux Geeksters. As you may know, Ubuntu and Debian are using Dash (Debian ASH) as the system’s default, non-interactive shell, due to the fact that bash has high memory requirements and so, the system would have needed more time to boot. Unlike Debian and Ubuntu which use sysVinit (for now), Fedora uses systemd as the default init service manager so Dash is not required for a faster boot process, because systemd handles things different then sysVinit.
But Bash may be unsafe, due to the fact that the Shellshock vulnerability has been discovered recently (and only partially patched) and the attackers are currently taking advantage of it in their attempt to hack servers.
While Bash is under the spotlight right now and a lot of tests are performed on it, most likely new exploits will be discovered.
This being said, one of the Fedora developers have asked on the mailing lists whether Debian’s dash or Android’s mksh would be a safer alternative, as the future system’s default, non-interactive shell.
For now, the discussions are in early stages, but we will keep you informed once a decision is being taken, regarding the default shell of the future Fedora systems.
If Bash gets replaced with either Dash or Mksh, the developers will have to modify the #!/bin/bash line (shebang) at the beginning of the system scripts and also port the scripts that are not Dash/Mksh compatible.
The latest Fedoras include both dash and mksh in the default repositories, so this changes are not that difficult to implement.
The system’s default shell refers to the scripts which are automatically executed by the operating system, the users still being able to use bash, zsh or any other shell they prefer.