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/* vi: set sw=4 ts=4: */
* Utility routines.
* Copyright (C) 1999-2004 by Erik Andersen <>
* Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
#include "libbb.h"
In Linux we have three ways to determine "process name":
1. /proc/PID/stat has "...(name)...", among other things. It's so-called "comm" field.
2. /proc/PID/cmdline's first NUL-terminated string. It's argv[0] from exec syscall.
3. /proc/PID/exe symlink. Points to the running executable file.
kernel threads:
comm: thread name
cmdline: empty
exe: <readlink fails>
comm: first 15 chars of base name
(if executable is a symlink, then first 15 chars of symlink name are used)
cmdline: argv[0] from exec syscall
exe: points to executable (resolves symlink, unlike comm)
script (an executable with #!/path/to/interpreter):
comm: first 15 chars of script's base name (symlinks are not resolved)
cmdline: /path/to/interpreter (symlinks are not resolved)
(script name is in argv[1], args are pushed into argv[2] etc)
exe: points to interpreter's executable (symlinks are resolved)
some commands started from busybox shell, xargs or find are started by
execXXX("/proc/self/exe", applet_name, params....)
and therefore comm field contains "exe".
/* find_pid_by_name()
* Modified by Vladimir Oleynik for use with libbb/procps.c
* This finds the pid of the specified process.
* Currently, it's implemented by rummaging through
* the proc filesystem.
* Returns a list of all matching PIDs
* It is the caller's duty to free the returned pidlist.
pid_t* find_pid_by_name(const char* procName)
pid_t* pidList;
int i = 0;
procps_status_t* p = NULL;
pidList = xmalloc(sizeof(*pidList));
while ((p = procps_scan(p, PSSCAN_PID|PSSCAN_COMM|PSSCAN_ARGV0))) {
if (
/* we require comm to match and to not be truncated */
/* in Linux, if comm is 15 chars, it may be a truncated
* name, so we don't allow that to match */
(!p->comm[sizeof(p->comm)-2] && strcmp(p->comm, procName) == 0)
/* or we require argv0 to match (essential for matching reexeced /proc/self/exe)*/
|| (p->argv0 && strcmp(bb_basename(p->argv0), procName) == 0)
/* TOOD: we can also try /proc/NUM/exe link, do we want that? */
) {
pidList = xrealloc(pidList, sizeof(*pidList) * (i+2));
pidList[i++] = p->pid;
pidList[i] = 0;
return pidList;
pid_t *pidlist_reverse(pid_t *pidList)
int i = 0;
while (pidList[i])
if (--i >= 0) {
pid_t k;
int j;
for (j = 0; i > j; i--, j++) {
k = pidList[i];
pidList[i] = pidList[j];
pidList[j] = k;
return pidList;