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RENICE(8) NetBSD System Manager's Manual RENICE(8)
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renice -- alter priority of running processes
renice priority [[-gpu] who ...] ...
renice -n increment [[-gpu] who ...] ...
renice alters the scheduling priority of one or more running processes.
The first argument is the new priority to apply, or if -n is given, the
change to make (applied additively) to the priority. This argument may
be negative. (The interpretation of priorities is discussed below.)
The following who parameters name the target processes, as either process
IDs, process group IDs, or user names. The -gpu options control the
interpretation as follows:
-g Interpret who parameters as process group ID's.
-p Interpret who parameters as process IDs. This is the default.
-u Interpret who parameters as user names.
Each who parameter is processed separately and updates the priority of
the processes it names as follows:
with -g All processes in the process group are updated to the selected
priority. If an increment is used, the increment is added to
the highest priority found among the members of the process
group prior to the change.
with -p The named process is updated to the selected priority. If an
increment is used, the increment is added to the process's pre-
with -u All processes belonging to the specified user are updated to the
selected priority. If an increment is used, the increment is
added to the highest priority found among the processes belong-
ing to the user prior to the change.
In conventional terminology a ``high priority'' process receives a lot of
CPU time and a ``low priority'' process receives relatively little.
``Niceness'' is the inverse concept: a process with a high niceness level
receives relatively little CPU time. It is about the process being nice
to the rest of the system, rather than the system being nice to the
The numerical priority values accepted by renice are called priorities
but are actually nicenesses. They range from PRIO_MIN (-20) to PRIO_MAX
(20). PRIO_MIN is the highest priority, lowest niceness, and receives
the most CPU time. PRIO_MAX is the lowest priority, highest niceness,
and receives the least CPU time. This is confusing but enshrined in his-
torical practice and standards. If in doubt, check with ps(1): processes
running with elevated priority (getting more CPU time) include `<' in the
FLAGS column; processes running with reduced priority (getting less CPU
time) show `N' for ``nice'' in FLAGS. The default priority is 0.
At priority 20, processes will specifically run only when nothing else
Users other than the super-user may only alter the priority of processes
they own, and only by increasing the niceness. (This prevents overriding
administrative fiats.) The super-user may alter the priority of any
process to any legal value.
/etc/passwd to map user names to user ID's
renice +1 987 -u daemon root -p 32
changes the priority of process ID's 987 and 32, and all processes owned
by users daemon and root.
nice(1), prenice(1), getpriority(2), setpriority(2)
The renice command appeared in 4.0BSD.
Non-super-users cannot increase scheduling priorities of their own pro-
cesses, even if they were the ones that decreased the priorities in the
NetBSD 9.99 October 22, 2020 NetBSD 9.99