- 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 [-F] [pid | core]...
/usr/bin/psig [-n] pid ...
/usr/bin/pstack [-F] pid | core [/lwp] ...
/usr/bin/pfiles [-Fn] pid...
/usr/bin/pwait [-v] pid...
/usr/bin/ptime 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 lwp in each process.
Print or set the credentials (effective, real, saved UIDs and GIDs) of each process.
List the signal actions and handlers of each process. See signal.h(3HEAD).
Print a hex+symbolic stack trace for each lwp in each process.
Report fstat(2) and fcntl(2) information for all open files in each process. 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 (PR_REQUESTED stop).
Set each process running (inverse of pstop).
Wait for all of the specified processes to terminate.
The following options are supported:
Force. Grabs the target process even if another process has control.
(psig and pfiles only) Sets non-verbose mode. psig displays signal 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 registers.
(pwait only) Verbose. Reports terminations to standard output.
Additionally, pcred supports the following options:
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 supplementary group list to the supplementary groups list of the specified login.
Sets the real, effective, and saved user ids (UIDs) of the target processes to the specified value.
In order to set the credentials of another process, a process must have sufficient privilege to change its user and group ids to those specified according to the rules laid out in setuid(2) and it must have sufficient 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 nothing 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 deadlock in this case.
Caution should be exercised when using the -F flag. Imposing two controlling 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 question.
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 information 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 not available.
The following exit values are returned:
An error has occurred.
See attributes(5) for descriptions of the following attributes:
Human Readable Output is Unstable. Options are Evolving.
gcore(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), signal.h(3HEAD), core(4), proc(4), process(4), attributes(5), zones(5)
The following proc tools stop their target processes while inspecting them and reporting the results: pfiles, pldd, and pstack.
A process can do nothing while it is stopped. Stopping a heavily used process in a production environment, even for a short amount of time, can cause severe bottlenecks and even hangs of these processes, 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 is traced using the above mentioned proc tools. Because of this, stopping a UNIX process in a production environment should be avoided.
A process 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.