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KVM_GETPROCS(3) NetBSD Library Functions Manual KVM_GETPROCS(3)
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kvm_getprocs, kvm_getargv, kvm_getenvv -- access user process state
Kernel Data Access Library (libkvm, -lkvm)
struct kinfo_proc *
kvm_getprocs(kvm_t *kd, int op, int arg, int *cnt);
kvm_getargv(kvm_t *kd, const struct kinfo_proc *p, int nchr);
kvm_getenvv(kvm_t *kd, const struct kinfo_proc *p, int nchr);
struct kinfo_proc2 *
kvm_getproc2(kvm_t *kd, int op, int arg, size_t elemsize, int *cnt);
kvm_getargv2(kvm_t *kd, const struct kinfo_proc2 *p, int nchr);
kvm_getenvv2(kvm_t *kd, const struct kinfo_proc2 *p, int nchr);
kvm_getprocs() returns a (sub-)set of active processes in the kernel
indicated by kd. The op and arg arguments constitute a predicate which
limits the set of processes returned. The value of op describes the fil-
tering predicate as follows:
KERN_PROC_ALL all processes
KERN_PROC_PID processes with process id arg
KERN_PROC_PGRP processes with process group arg
KERN_PROC_SESSION processes with session id arg
KERN_PROC_TTY processes with tty device arg
KERN_PROC_UID processes with effective user id arg
KERN_PROC_RUID processes with real user id arg
KERN_PROC_GID processes with effective group id arg
KERN_PROC_RGID processes with real group id arg
The number of processes found is returned in the reference parameter cnt.
The processes are returned as a contiguous array of kinfo_proc struc-
tures. This memory is locally allocated, and subsequent calls to
kvm_getprocs() and kvm_close() will overwrite this storage.
If the op argument for kvm_getprocs() is KERN_PROC_TTY, arg can also be
KERN_PROC_TTY_NODEV to select processes with no controlling tty and
KERN_PROC_TTY_REVOKE to select processes which have had their controlling
kvm_getargv() returns a null-terminated argument vector that corresponds
to the command line arguments passed to process indicated by p. Most
likely, these arguments correspond to the values passed to exec(3) on
process creation. This information is, however, deliberately under con-
trol of the process itself. Note that the original command name can be
found, unaltered, in the p_comm field of the process structure returned
The nchr argument indicates the maximum number of characters, including
null bytes, to use in building the strings. If this amount is exceeded,
the string causing the overflow is truncated and the partial result is
returned. This is handy for programs like ps(1) and w(1) that print only
a one line summary of a command and should not copy out large amounts of
text only to ignore it. If nchr is zero, no limit is imposed and all
argument strings are returned in their entirety.
The memory allocated to the argv pointers and string storage is owned by
the kvm library. Subsequent kvm_getprocs() and kvm_close(3) calls will
clobber this storage.
The kvm_getenvv() function is similar to kvm_getargv() but returns the
vector of environment strings. This data is also alterable by the
kvm_getproc2() is similar to kvm_getprocs() but returns an array of
kinfo_proc2 structures. Additionally, only the first elemsize bytes of
each array entry are returned. If the size of the kinfo_proc2 structure
increases in size in a future release of NetBSD the kernel will only
return the requested amount of data for each array entry and programs
that use kvm_getproc2() will continue to function without the need for
The kvm_getargv2() and kvm_getenvv2() are equivalents to the
kvm_getargv() and kvm_getenvv() functions but use a kinfo_proc2 structure
to specify the process.
If called against an active kernel, the kvm_getproc2(), kvm_getargv2(),
and kvm_getenvv2() functions will use the sysctl(3) interface and do not
require access to the kernel memory device file or swap device.
kvm_getprocs(), kvm_getargv(), kvm_getenvv(), kvm_getproc2(),
kvm_getargv2(), and kvm_getenvv2() all return NULL on failure.
kvm(3), kvm_close(3), kvm_geterr(3), kvm_nlist(3), kvm_open(3),
kvm_openfiles(3), kvm_read(3), kvm_write(3)
These routines do not belong in the kvm interface.
NetBSD 8.0 January 9, 2018 NetBSD 8.0