HP Visualize J210XC IRIX to HP-UX Migration Guide - Page 39

Signals

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Managing Processes 1. POSIX standard priority (tunable parameter): The highest priorities, known as RTSCHED priorities. RTSCHED processes have a range of priorities separate from other HP-UX priorities. The number of RTSCHED priorities is a user tunable parameter (rtsched_numpri), set between 32 and 512 (default 32). 2. Real-time priority (0-127): Reserved for SCHED_RTPRIO processes started with rtprio() system calls. 3. System priority (128-177): Used by system processes. 4. User priority (178-255): Assigned to user processes. The kernel can alter the priority of time-share priorities (128-255) but not real-time priorities (0-127). HP-UX uses the AT&T version of nice values, which run from 0 to 39 with a default of 20. The lowest priority is 39; the highest priority is 0. Note that both Korn and C shells handle nice slightly differently. ksh automatically lowers priority of background processes by four; this behavior can be modified using the bgnice argument. If you specify nice from ksh, it executes /usr/bin/nice and lowers priority by ten. If you specify nice from csh, it executes its built-in command and lowers priority by four; however, if you specify /usr/bin/nice, csh lowers priority by ten. The renice command (/usr/sbin/renice) allows you to alter the priority of running processes. Running processes can also be altered from the Process Management area of SAM. The HP-UX version of renice has the following syntax: # renice -n priority_change PID The new system nice value is equal to 20 + priority_change, and is limited to the range 0 through 39. If priority_change is a negative value, priority is increased, provided the user has appropriate privileges. HP-UX supports job control for both the POSIX, Korn, and C shells. Job control provides users with greater flexibility in managing and controlling jobs. For example, you can: • Temporarily suspend a foreground job, by pressing CTRL-Z. This can be customized using the stty command. • Bring a background job into the foreground, using the fg built-in shell command. • Move a foreground job into the background, using the bg built-in shell command. Signals HP-UX signals look like the following kill command: # /usr/bin/kill -l NULL HUP INT QUIT ILL TRAP ABRT EMT FPE KILL BUS SEGV SYS 34

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Managing Processes
34
1.
POSIX standard priority (tunable parameter): The highest priorities, known as RTSCHED priorities.
RTSCHED processes have a range of priorities separate from other HP-UX priorities. The number of
RTSCHED priorities is a user tunable parameter (
rtsched_numpri
), set between
32
and
512
(default
32
).
2.
Real-time priority (
0-127
): Reserved for SCHED_RTPRIO processes started with
rtprio()
system
calls.
3.
System priority (
128-177
): Used by system processes.
4.
User priority (
178-255
): Assigned to user processes.
The kernel can alter the priority of time-share priorities (
128-255
) but not real-time priorities (
0-127
).
HP-UX uses the AT&T version of
nice
values, which run from
0
to
39
with a default of
20
. The lowest
priority is
39
; the highest priority is
0
.
Note that both
Korn
and
C
shells handle
nice
slightly differently.
ksh
automatically lowers priority of
background processes by four; this behavior can be modified using the
bgnice
argument. If you specify
nice
from
ksh
, it executes
/usr/bin/nice
and lowers priority by ten. If you specify nice from
csh
, it executes
its built-in command and lowers priority by four; however, if you specify
/usr/bin/nice
,
csh
lowers priority
by ten.
The
renice
command (
/usr/sbin/renice
) allows you to alter the priority of running processes. Running
processes can also be altered from the Process Management area of SAM. The HP-UX version of
renice
has the following syntax:
# renice -n priority_change PID
The new system
nice
value is equal to
20
+
priority_change
, and is limited to the range
0
through
39
. If
priority_change
is a negative value, priority is increased, provided the user has appropriate privileges.
HP-UX supports job control for both the POSIX,
Korn
, and
C
shells. Job control provides users with
greater flexibility in managing and controlling jobs. For example, you can:
•
Temporarily suspend a foreground job, by pressing
CTRL-Z
. This can be customized using the
stty
command.
•
Bring a background job into the foreground, using the
fg
built-in shell command.
•
Move a foreground job into the background, using the
bg
built-in shell command.
Signals
HP-UX signals look like the following
kill
command:
# /usr/bin/kill –l
NULL
HUP
INT
QUIT
ILL
TRAP
ABRT
EMT
FPE
KILL
BUS
SEGV
SYS