Ubuntu one remote uses sudo -S -p '' halt
for shutdown and does not work to the end.
leaveing monitor on with message
will now halt
[22225.11163] halted
What is the difference between sudo -S -p " halt
and sudo shutdown now
?
Ubuntu one remote uses sudo -S -p '' halt
for shutdown and does not work to the end.
leaveing monitor on with message
will now halt
[22225.11163] halted
What is the difference between sudo -S -p " halt
and sudo shutdown now
?
The -S
and -p
switches for sudo
have no importance in this case. Here is what they do, respectively.
The
-S
switch causessudo
to read the password from STDIN. This allows, for example, a password to be piped tosudo
throughecho
orcat
.
The
-p
switch allows you to override the default password prompt and use a custom one, or none at all.
The important difference is in the two commands being issued by sudo
.
The
halt
command, if invoked without the-p
switch, simply halts the OS and stops all CPUs. Once the system is cleanly halted, the user may safely hit the Power button on his computer manually.
The
poweroff
,shutdown -h now
, andhalt -p
commands all do the same thing ashalt
alone, while additionally sending an ACPI command to signal the power supply unit to disconnect the main power. This prevents you from having to physically push the Power button on your computer.