Persistent processes that make up an instance.
This background processes are started from Linux/Windows with the help of only one binary executable program named oracle.
The background process are then threads of the oracle executable.
A background process is defined as any process that is listed in VPROCESS and has a non-null value in the pname column.
See the PROCESSES parameter
ps -u oracle -f
UID PID PPID C STIME TTY TIME CMD
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oracle 29608 1 0 15:52 ? 00:00:00 ora_pmon_oel11g
oracle 29610 1 0 15:52 ? 00:00:00 ora_vktm_oel11g
oracle 29614 1 0 15:52 ? 00:00:00 ora_gen0_oel11g
oracle 29616 1 0 15:52 ? 00:00:00 ora_diag_oel11g
oracle 29618 1 0 15:52 ? 00:00:00 ora_dbrm_oel11g
oracle 29620 1 0 15:52 ? 00:00:00 ora_psp0_oel11g
oracle 29622 1 0 15:52 ? 00:00:00 ora_dia0_oel11g
oracle 29624 1 2 15:52 ? 00:00:02 ora_mman_oel11g
oracle 29626 1 0 15:52 ? 00:00:00 ora_dbw0_oel11g
oracle 29628 1 0 15:52 ? 00:00:00 ora_lgwr_oel11g
oracle 29630 1 0 15:52 ? 00:00:00 ora_ckpt_oel11g
oracle 29632 1 0 15:52 ? 00:00:00 ora_smon_oel11g
oracle 29634 1 0 15:52 ? 00:00:00 ora_reco_oel11g
oracle 29636 1 0 15:52 ? 00:00:00 ora_mmon_oel11g
oracle 29638 1 0 15:52 ? 00:00:00 ora_mmnl_oel11g
oracle 29640 1 0 15:52 ? 00:00:00 ora_d000_oel11g
oracle 29642 1 0 15:52 ? 00:00:00 ora_s000_oel11g
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pslist oracle
pslist -d oracle