proc, pflags, pcred, pldd, psig, pstack, pfiles, pwdx, pstop, prun,
pwait, ptime - proc tools
/usr/bin/pflags [-r] pid | core [/lwp] ...
/usr/bin/pcred [pid | core]...
/usr/bin/pcred [-u user/uid] [-g group/gid] [-G grouplist] pid...
/usr/bin/pcred -l login pid...
/usr/bin/pldd [-Fl] [pid | core]...
/usr/bin/psig [-n] pid...
/usr/bin/pstack [-F] pid | core [/lwp] ...
/usr/bin/pfiles [-Fn] pid | core...
/usr/bin/pstop pid[/lwp] ...
/usr/bin/prun pid[/lwp] ...
/usr/bin/pwait [-v] pid...
/usr/bin/ptime [-Fm] -p pidlist
/usr/bin/ptime [-m]command [arg]...
The proc tools are utilities that exercise features of /proc (see
proc(4)). Most of them take a list of process-ids (pid). The tools that
do take process-ids also accept /proc/nnn as a process-id, so the shell
expansion /proc/* can be used to specify all processes in the system.
Some of the proc tools can also be applied to core files (see core(4)).
The tools that apply to core files accept a list of either process IDs
or names of core files or both.
Some of the proc tools can operate on individual threads. Users can
examine only selected threads by appending /thread-id to the process-id
or core. Multiple threads can be selected using the - and , delimiters.
For example /1,2,7-9 examines threads 1, 2, 7, 8, and 9.
Print the /proc tracing flags, the pending and held signals,
and other /proc status information for each process or speci‐
fied lwps in each process.
Print or set the credentials (effective, real, saved UIDs and
GIDs) of each process.
List the dynamic libraries linked into each process, includ‐
ing shared objects explicitly attached using dlopen(3C). See
List the signal actions and handlers of each process. See
Print a hex+symbolic stack trace for each process or speci‐
fied lwps in each process.
Report fstat(2) and fcntl(2) information for all open files
in each process. For network endpoints, the local (and peer
if connected) address information is also provided. For sock‐
ets, the socket type, socket options and send and receive
buffer sizes are also provided. In addition, a path to the
file is reported if the information is available from
/proc/pid/path. This is not necessarily the same name used
to open the file. See proc(4) for more information.
Print the current working directory of each process.
Stop each process or the specified lwps (PR_REQUESTED stop).
Set running each process or the specified lwps (the inverse
Wait for all of the specified processes to terminate.
Time the command, like time(1), but using microstate account‐
ing for reproducible precision. Unlike time(1), children of
the command are not timed.
If the -p pidlist version is used, display a snapshot of tim‐
ing statistics for the specified processes. The pidlist may
either be a comma delineated list or a space delineated list.
Space delineated lists must be properly quoted to assure that
they are in a single argument.
The following general options are supported:
Force. Grabs the target process even if another process has con‐
(psig and pfiles only) Sets non-verbose mode. psig displays sig‐
nal handler addresses rather than names. pfiles does not display
verbose information for each file descriptor. Instead, pfiles
limits its output to the information that would be retrieved if
the process applied fstat(2) to each of its file descriptors.
(pflags only) If the process is stopped, displays its machine
(pwait only) Verbose. Reports terminations to standard output.
In addition to the general options, pcred supports the following
Sets the real, effective, and saved group ids (GIDs) of
the target processes to the specified value.
Sets the supplementary GIDs of the target process to
the specified list of groups. The supplementary groups
should be specified as a comma-separated list of group
names ids. An empty list clears the supplementary group
list of the target processes.
Sets the real, effective, and saved UIDs of the target
processes to the UID of the specified login. Sets the
real, effective, and saved GIDs of the target processes
to the GID of the specified login. Sets the supplemen‐
tary group list to the supplementary groups list of the
Sets the real, effective, and saved user ids (UIDs) of
the target processes to the specified value.
In addition to the general options, pldd supports the following option:
Shows unresolved dynamic linker map names.
In addition to the general options, ptime supports the following
Display the full set of microstate accounting statistics.
The displayed fields are as follows:
Wall clock time.
User level CPU time.
System call CPU time.
Other system trap CPU time.
Text page fault sleep time.
Data page fault sleep time.
Kernel page fault sleep time.
User lock wait sleep time.
All other sleep time.
CPU latency (wait) time.
Displays a snapshot of timing statistics for the specified
To set the credentials of another process, a process must have suffi‐
cient privilege to change its user and group ids to those specified
according to the rules laid out in setuid(2) and it must have suffi‐
cient privilege to control the target process.
These proc tools stop their target processes while inspecting them and
reporting the results: pfiles, pldd, and pstack. A process can do noth‐
ing while it is stopped. Thus, for example, if the X server is
inspected by one of these proc tools running in a window under the X
server's control, the whole window system can become deadlocked because
the proc tool would be attempting to print its results to a window that
cannot be refreshed. Logging in from from another system using
rlogin(1) and killing the offending proc tool would clear up the dead‐
lock in this case.
Caution should be exercised when using the -F flag. Imposing two con‐
trolling processes on one victim process can lead to chaos. Safety is
assured only if the primary controlling process, typically a debugger,
has stopped the victim process and the primary controlling process is
doing nothing at the moment of application of the proc tool in ques‐
Some of the proc tools can also be applied to core files, as shown by
the synopsis above. A core file is a snapshot of a process's state and
is produced by the kernel prior to terminating a process with a signal
or by the gcore(1) utility. Some of the proc tools can need to derive
the name of the executable corresponding to the process which dumped
core or the names of shared libraries associated with the process.
These files are needed, for example, to provide symbol table informa‐
tion for pstack(1). If the proc tool in question is unable to locate
the needed executable or shared library, some symbol information is
unavailable for display. Similarly, if a core file from one operating
system release is examined on a different operating system release, the
run-time link-editor debugging interface (librtld_db) cannot be able to
initialize. In this case, symbol information for shared libraries is
The following exit values are returned:
An error has occurred.
See attributes(5) for descriptions of the following attributes:
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
│Interface Stability │ See below. │
The human readable output is Uncommitted. The options are Committed.
SEE ALSOgcore(1), ldd(1), pargs(1), pgrep(1), pkill(1), plimit(1), pmap(1),
preap(1), ps(1), ptree(1), ppgsz(1), pwd(1), rlogin(1), time(1),
truss(1), wait(1), fcntl(2), fstat(2), setuid(2), dlopen(3C), sig‐
nal.h(3HEAD), core(4), proc(4), process(4), attributes(5), zones(5)WARNINGS
The following proc tools stop their target processes while inspecting
them and reporting the results: pfiles, pldd, and pstack. However,
even if pstack operates on an individual thread, it stops the whole
A process or thread can do nothing while it is stopped. Stopping a
heavily used process or thread in a production environment, even for a
short amount of time, can cause severe bottlenecks and even hangs of
these processes or threads, causing them to be unavailable to users.
Some databases could also terminate abnormally. Thus, for example, a
database server under heavy load could hang when one of the database
processes or threads is traced using the above mentioned proc tools.
Because of this, stopping a UNIX process or thread in a production
environment should be avoided.
A process or thread being stopped by these tools can be identified by
issuing /usr/bin/ps -eflL and looking for "T" in the first column.
Notice that certain processes, for example "sched", can show the "T"
status by default most of the time.
The process ID returned for locked files on network file systems might
not be meaningful.
Apr 01, 2013 PROC(1)