openproc man page

#include <proc/readproc.h>

PROCTAB* openproc (int flags, ... );
void closeproc (PROCTAB* PT);

The openproc function initializes a PROCTAB structure which can be used by iterated readproc calls to get information on current processes. Depending on flags, openproc may need a second argument or a second and third argument (see below).

closeproc closes all files opened by openproc and deallocates the memory allocated by openproc.

The PROCTAB structure is defined in <proc/readproc.h>

openproc returns a pointer to a PROCTAB structure, or NULL if an error occurs. This usually means that /proc cannot be read by the process.

The behaviour of openproc is controlled by the following set of flags, which may be ORed together. There are three different kinds of flags. The first group of flags determins which information gets read from /proc/#pid for each process. The second group of flags (of which only one can be enacted for a opendir call) restricts which processes information is read for by providing a list of criteria. The third group of flags restricts this as well, but doesn't need arguments. These may be used together again.

PROC_FILLMEM

read information from /proc/#pid/statm

PROC_FILLCOM

allocate cmdline part of proc_t and read information from /proc/#pid/cmdline

PROC_FILLENV

allocate environ part of proc_t and read information from /proc/#pid/environ

PROC_FILLUSR

resolve user ids to names via /etc/passwd

PROC_FILLGRP

resolve group ids to names via /etc/group

PROC_FILLSTATUS

read information from /proc/#pid/status

PROC_FILLSTAT

read information from /proc/#pid/stat

PROC_FILLWCHAN

do WCHAN lookup

PROC_FILLARG

equivalent to PROC_FILLCOM

PROC_FILLCGROUP

alloc and fill in cgroup

PROC_FILLSUPGRP

resolve supplementary group id -> group name

PROC_FILLOOM

fill in proc_t oom_score and oom_adj

PROC_FILLNS

fill in proc_t namespace information

PROC_FILLSYSTEMD

fill in proc_t systemd information

PROC_LOOSE_TASKS

threat threads as if they were processes

PROC_PID (2nd argument pid_t* pidlist)

lookup only processes whose pid is contained in pidlist (the list is terminated with 0)

PROC_UID (arguments uid_t* uidlist, int n)

lookup only processes whose user id is contained in uidlist (where n is the number of uids contained in the list)

PROC_EDITCGRPCVT

edit cgroup as single vector

PROC_EDITCMDLCVT

edit cmdline as single vector

PROC_EDITENVRCVT

edit environ as single vector

Only one of the flags needing additional arguments (PROC_{PID,UID}) may be used at a time.

readproc(3), readproctab(3), /proc/, /usr/include/proc/readproc.h,

Please send bug reports to procps@freelists.org

readproc(3), readproctab(3).