на тех скриптах что нужно системе это малозаметно
> The major reason to switch the default shell was efficiency. bash is an excellent full-featured shell appropriate for interactive use; indeed, it is still the default login shell. However, it is rather large and slow to start up and operate by comparison with dash. A large number of shell instances are started as part of the Ubuntu boot process. Rather than change each of them individually to run explicitly under /bin/dash, a change which would require significant ongoing maintenance and which would be liable to regress if not paid close attention, the Ubuntu core development team felt that it was best simply to change the default shell. The boot speed improvements in Ubuntu 6.10 were often incorrectly attributed to Upstart, which is a fine platform for future development of the init system but in Ubuntu 6.10 was primarily running in System V compatibility mode with only small behavioural changes. These improvements were in fact largely due to the changed /bin/sh.
