List, Query, Manipulate System Processes
ps implements an API to query and manipulate system processes. Most of its code is based on the psutil Python package.
- Installation
- Supported platforms
- Listing all processes
- Process API
- Finished and zombie processes
- Pid reuse
- Recipes
- Code of Conduct
- License
You can install the released version of ps from CRAN with:
install.packages("ps")If you need the development version, install it with
pak::pak("r-lib/ps")library(ps)
library(pillar) # nicer printing of data framesps currently supports Windows (from Vista), macOS and Linux systems. On
unsupported platforms the package can be installed and loaded, but all
of its functions fail with an error of class "not_implemented".
ps_pids() returns all process ids on the system. This can be useful to
iterate over all processes.
ps_pids()[1:20]## [1] 0 1 265 266 275 276 557 559 561 562 564 567 569 570 574 578 580 584 586 587
ps() returns a data frame, with data about each process. It contains a
handle to each process, in the ps_handle column, you can use these to
perform more queries on the processes.
ps()## # A data frame: 572 × 11
## pid ppid name username status user system rss vms created ps_handle
## * <int> <int> <chr> <chr> <chr> <dbl> <dbl> <dbl> <dbl> <dttm> <I<list>>
## 1 45911 4159 Google C… gaborcs… sleep… 0.0473 0.0227 1.05e8 1.91e12 2025-04-28 08:05:25 <ps_handl>
## 2 45860 4159 Google C… gaborcs… sleep… 0.0751 0.0347 1.21e8 1.91e12 2025-04-28 08:05:19 <ps_handl>
## 3 45700 1 mdworker… gaborcs… sleep… 0.327 0.0861 2.88e7 4.37e11 2025-04-28 08:04:26 <ps_handl>
## 4 44844 39673 R gaborcs… runni… 1.70 0.634 2.55e8 4.22e11 2025-04-28 08:01:34 <ps_handl>
## 5 44738 4159 Google C… gaborcs… sleep… 0.0325 0.0157 4.77e7 4.89e11 2025-04-28 08:00:51 <ps_handl>
## 6 43786 1 Messages… gaborcs… sleep… 0.162 0.233 6.90e6 4.37e11 2025-04-28 07:59:53 <ps_handl>
## 7 43785 1 business… gaborcs… sleep… 0.110 0.112 8.72e6 4.37e11 2025-04-28 07:59:53 <ps_handl>
## 8 43628 1 MENotifi… gaborcs… sleep… 0.0291 0.0116 3.08e6 4.21e11 2025-04-28 07:59:35 <ps_handl>
## 9 43627 1 MTLAsset… gaborcs… sleep… 0.0498 0.0208 3.29e6 4.37e11 2025-04-28 07:59:35 <ps_handl>
## 10 43472 1 replayd gaborcs… sleep… 2.32 0.560 2.46e7 4.37e11 2025-04-28 07:59:21 <ps_handl>
## # ℹ 562 more rows
This is a short summary of the API. Please see the documentation of the various methods for details, in particular regarding handles to finished processes and pid reuse. See also “Finished and zombie processes” and “pid reuse” below.
ps_handle(pid) creates a process handle for the supplied process id.
If pid is omitted, a handle to the calling process is returned:
p <- ps_handle()
p## <ps::ps_handle> PID=44844, NAME=R, AT=2025-04-28 08:01:34.873763
ps_pid(p) returns the pid of the process.
ps_pid(p)## [1] 44844
ps_create_time() returns the creation time of the process (according
to the OS).
ps_create_time(p)## [1] "2025-04-28 08:01:34 GMT"
The process id and the creation time uniquely identify a process in a system. ps uses them to make sure that it reports information about, and manipulates the correct process.
ps_is_running(p) returns whether p is still running. It handles pid
reuse safely.
ps_is_running(p)## [1] TRUE
ps_ppid(p) returns the pid of the parent of p.
ps_ppid(p)## [1] 39673
ps_parent(p) returns a process handle to the parent process of p.
ps_parent(p)## <ps::ps_handle> PID=39673, NAME=zsh, AT=2025-04-28 07:53:00.030062
ps_name(p) returns the name of the program p is running.
ps_name(p)## [1] "R"
ps_exe(p) returns the full path to the executable the p is running.
ps_exe(p)## [1] "/Library/Frameworks/R.framework/Versions/4.5-arm64/Resources/bin/exec/R"
ps_cmdline(p) returns the command line (executable and arguments) of
p.
ps_cmdline(p)## [1] "/Library/Frameworks/R.framework/Versions/4.5-arm64/Resources/bin/exec/R"
ps_status(p) returns the status of the process. Possible values are OS
dependent, but typically there is "running" and "stopped".
ps_status(p)## [1] "running"
ps_username(p) returns the name of the user the process belongs to.
ps_username(p)## [1] "gaborcsardi"
ps_uids(p) and ps_gids(p) return the real, effective and saved user
ids of the process. They are only implemented on POSIX systems.
if (ps_os_type()[["POSIX"]]) ps_uids(p)## real effective saved
## 501 501 501
if (ps_os_type()[["POSIX"]]) ps_gids(p)## real effective saved
## 20 20 20
ps_cwd(p) returns the current working directory of the process.
ps_cwd(p)## [1] "/Users/gaborcsardi/works/ps"
ps_terminal(p) returns the name of the terminal of the process, if
any. For processes without a terminal, and on Windows it returns
NA_character_.
ps_terminal(p)## [1] "/dev/ttys019"
ps_environ(p) returns the environment variables of the process.
ps_environ_raw(p) does the same, in a different form. Typically they
reflect the environment variables at the start of the process.
ps_environ(p)[c("TERM", "USER", "SHELL", "R_HOME")]## TERM xterm-256color
## USER gaborcsardi
## SHELL /bin/zsh
## R_HOME /Library/Frameworks/R.framework/Versions/4.5-arm64/Resources
ps_num_threads(p) returns the current number of threads of the
process.
ps_num_threads(p)## [1] 3
ps_cpu_times(p) returns the CPU times of the process, similarly to
proc.time().
ps_cpu_times(p)## user system children_user children_system
## 1.7681955 0.6514954 NA NA
ps_memory_info(p) returns memory usage information. See the manual for
details.
ps_memory_info(p)## rss vms pfaults pageins
## 261783552 421933465600 41422 13
ps_children(p) lists all child processes (potentially recursively) of
the current process.
ps_children(ps_parent(p))## [[1]]
## <ps::ps_handle> PID=39874, NAME=zsh, AT=2025-04-28 07:53:00.889347
##
## [[2]]
## <ps::ps_handle> PID=44844, NAME=R, AT=2025-04-28 08:01:34.873763
ps_num_fds(p) returns the number of open file descriptors (handles on
Windows):
ps_num_fds(p)## [1] 23
f <- file(tmp <- tempfile(), "w")
ps_num_fds(p)## [1] 24
close(f)
unlink(tmp)ps_open_files(p) lists all open files:
ps_open_files(p)## # A data frame: 4 × 2
## fd path
## <int> <chr>
## 1 0 /dev/ttys019
## 2 1 /dev/ttys019
## 3 2 /dev/ttys019
## 4 14 /private/var/folders/ph/fpcmzfd16rgbbk8mxvy9m2_h0000gn/T/RtmpoaXwPG/Rfaf2c3705b93c
f <- file(tmp <- tempfile(), "w")
ps_open_files(p)## # A data frame: 5 × 2
## fd path
## <int> <chr>
## 1 0 /dev/ttys019
## 2 1 /dev/ttys019
## 3 2 /dev/ttys019
## 4 14 /private/var/folders/ph/fpcmzfd16rgbbk8mxvy9m2_h0000gn/T/RtmpoaXwPG/Rfaf2c3705b93c
## 5 23 /private/var/folders/ph/fpcmzfd16rgbbk8mxvy9m2_h0000gn/T/RtmpoaXwPG/fileaf2c58c42e5c
close(f)
unlink(tmp)
ps_open_files(p)## # A data frame: 4 × 2
## fd path
## <int> <chr>
## 1 0 /dev/ttys019
## 2 1 /dev/ttys019
## 3 2 /dev/ttys019
## 4 14 /private/var/folders/ph/fpcmzfd16rgbbk8mxvy9m2_h0000gn/T/RtmpoaXwPG/Rfaf2c3705b93c
ps_suspend(p) suspends (stops) the process. On POSIX it sends a
SIGSTOP signal. On Windows it stops all threads.
ps_resume(p) resumes the process. On POSIX it sends a SIGCONT signal.
On Windows it resumes all stopped threads.
ps_send_signal(p) sends a signal to the process. It is implemented on
POSIX systems only. It makes an effort to work around pid reuse.
ps_terminate(p) send SIGTERM to the process. On POSIX systems only.
ps_kill(p) terminates the process. Sends SIGKILL on POSIX systems,
uses TerminateProcess() on Windows. It make an effort to work around
pid reuse.
ps_interrupt(p) interrupts a process. It sends a SIGINT signal on
POSIX systems, and it can send a CTRL+C or a CTRL+BREAK event on
Windows.
ps handles finished and Zombie processes as much as possible.
The essential ps_pid(), ps_create_time(), ps_is_running()
functions and the format() and print() methods work for all
processes, including finished and zombie processes. Other functions fail
with an error of class "no_such_process" for finished processes.
The ps_ppid(), ps_parent(), ps_children(), ps_name(),
ps_status(), ps_username(), ps_uids(), ps_gids(),
ps_terminal(), ps_children() and the signal sending functions work
properly for zombie processes. Other functions fail with
"zombie_process" error.
ps functions handle pid reuse as well as technically possible.
The query functions never return information about the wrong process, even if the process has finished and its process id was re-assigned.
On Windows, the process manipulation functions never manipulate the wrong process.
On POSIX systems, this is technically impossible, it is not possible to send a signal to a process without creating a race condition. In ps the time window of the race condition is very small, a few microseconds, and the process would need to finish, and the OS would need to reuse its pid within this time window to create problems. This is very unlikely to happen.
In the spirit of psutil recipes.
Using ps() and dplyr:
library(dplyr)
find_procs_by_name <- function(name) {
ps() |>
filter(name == !!name) |>
pull(ps_handle)
}
find_procs_by_name("R")## [[1]]
## <ps::ps_handle> PID=44844, NAME=R, AT=2025-04-28 08:01:34.873763
##
## [[2]]
## <ps::ps_handle> PID=32722, NAME=R, AT=2025-04-28 07:36:42.295781
Without creating the full table of processes:
find_procs_by_name <- function(name) {
procs <- lapply(ps_pids(), function(p) {
tryCatch({
h <- ps_handle(p)
if (ps_name(h) == name) h else NULL },
no_such_process = function(e) NULL,
access_denied = function(e) NULL
)
})
procs[!vapply(procs, is.null, logical(1))]
}
find_procs_by_name("R")## [[1]]
## <ps::ps_handle> PID=32722, NAME=R, AT=2025-04-28 07:36:42.295781
##
## [[2]]
## <ps::ps_handle> PID=44844, NAME=R, AT=2025-04-28 08:01:34.873763
ps_wait(), from ps 1.8.0, implements a new way, efficient for waiting
on a list of processes, so this is now very easy:
px <- processx::process$new("sleep", "2")
p <- px$as_ps_handle()
ps_wait(p, 1000)## [1] FALSE
ps_wait(p)## [1] TRUE
Again, this is much simpler with ps_wait(), added in ps 1.8.0.
px1 <- processx::process$new("sleep", "10")
px2 <- processx::process$new("sleep", "10")
px3 <- processx::process$new("sleep", "1")
px4 <- processx::process$new("sleep", "1")
p1 <- px1$as_ps_handle()
p2 <- px2$as_ps_handle()
p3 <- px3$as_ps_handle()
p4 <- px4$as_ps_handle()
ps_wait(list(p1, p2, p3, p4), timeout = 2000)## [1] FALSE FALSE TRUE TRUE
From ps 1.8.0, ps_kill() will first send SIGTERM signals on Unix,
and SIGKILL after a grace period, if needed.
Note, that some R IDEs, including RStudio, run a multithreaded R
process, and other threads may start processes as well.
reap_children() will clean up all these as well, potentially causing
the IDE to misbehave or crash.
kill_proc_tree <- function(pid, include_parent = TRUE, ...) {
if (pid == Sys.getpid() && include_parent) stop("I refuse to kill myself")
parent <- ps_handle(pid)
children <- ps_children(parent, recursive = TRUE)
if (include_parent) children <- c(children, list(parent))
ps_kill(children, ...)
}
p1 <- processx::process$new("sleep", "10")
p2 <- processx::process$new("sleep", "10")
p3 <- processx::process$new("sleep", "10")
kill_proc_tree(Sys.getpid(), include_parent = FALSE)## [1] "terminated" "terminated" "terminated" "terminated" "terminated"
Process name ending with “sh”:
ps() |>
filter(grepl("sh$", name))## # A data frame: 35 × 11
## pid ppid name username status user system rss vms created
## <int> <int> <chr> <chr> <chr> <dbl> <dbl> <dbl> <dbl> <dttm>
## 1 41838 1 ReportCrash root sleepi… NA NA NA NA 2025-04-28 07:57:52
## 2 40290 40090 zsh gaborcsardi sleepi… 0.0361 0.154 3.01e6 4.21e11 2025-04-28 07:53:47
## 3 40090 40088 zsh gaborcsardi sleepi… 0.587 0.406 3.14e7 4.21e11 2025-04-28 07:53:47
## 4 39874 39673 zsh gaborcsardi sleepi… 0.00552 0.0208 2.62e6 4.21e11 2025-04-28 07:53:00
## 5 39673 39672 zsh gaborcsardi sleepi… 0.270 0.0922 2.96e7 4.21e11 2025-04-28 07:53:00
## 6 35995 35795 zsh gaborcsardi sleepi… 0.0117 0.0485 9.67e5 4.21e11 2025-04-28 07:45:03
## 7 35795 35794 zsh gaborcsardi sleepi… 0.236 0.128 1.69e6 4.21e11 2025-04-28 07:45:03
## 8 35595 35391 zsh gaborcsardi sleepi… 0.00781 0.0332 9.67e5 4.21e11 2025-04-28 07:44:16
## 9 35391 35390 zsh gaborcsardi sleepi… 0.262 0.115 1.69e6 4.21e11 2025-04-28 07:44:15
## 10 30303 30302 bash gaborcsardi sleepi… 0.00806 0.0194 8.68e5 4.20e11 2025-04-28 07:32:12
## # ℹ 25 more rows
## # ℹ 1 more variable: ps_handle <I<list>>
Processes owned by user:
ps() |>
filter(username == Sys.info()[["user"]]) |>
select(pid, name)## # A data frame: 347 × 2
## pid name
## <int> <chr>
## 1 45911 Google Chrome Helper (Renderer)
## 2 45860 Google Chrome Helper (Renderer)
## 3 45700 mdworker_shared
## 4 44844 R
## 5 44738 Google Chrome Helper
## 6 43786 MessagesBlastDoorService
## 7 43785 businessservicesd
## 8 43628 MENotificationAgent
## 9 43627 MTLAssetUpgraderD
## 10 43472 replayd
## # ℹ 337 more rows
Processes consuming more than 100MB of memory:
ps() |>
filter(rss > 100 * 1024 * 1024)## # A data frame: 20 × 11
## pid ppid name username status user system rss vms created ps_handle
## <int> <int> <chr> <chr> <chr> <dbl> <dbl> <dbl> <dbl> <dttm> <I<list>>
## 1 45911 4159 Google… gaborcs… sleep… 4.73e-2 2.27e-2 1.05e8 1.91e12 2025-04-28 08:05:25 <ps_handl>
## 2 45860 4159 Google… gaborcs… sleep… 7.51e-2 3.47e-2 1.21e8 1.91e12 2025-04-28 08:05:19 <ps_handl>
## 3 44844 39673 R gaborcs… runni… 2.08e+0 9.20e-1 2.80e8 4.22e11 2025-04-28 08:01:34 <ps_handl>
## 4 40521 4159 Google… gaborcs… sleep… 3.14e+0 4.45e-1 2.03e8 1.91e12 2025-04-28 07:54:07 <ps_handl>
## 5 40037 4159 Google… gaborcs… sleep… 7.78e+0 1.03e+0 2.66e8 1.91e12 2025-04-28 07:53:23 <ps_handl>
## 6 39666 4159 Google… gaborcs… sleep… 1.30e+0 2.37e-1 1.45e8 1.91e12 2025-04-28 07:52:34 <ps_handl>
## 7 28176 4159 Google… gaborcs… sleep… 1.16e+1 1.09e+0 2.18e8 1.91e12 2025-04-28 07:23:37 <ps_handl>
## 8 18695 4159 Google… gaborcs… sleep… 2.33e+1 2.18e+0 2.23e8 1.91e12 2025-04-28 06:48:50 <ps_handl>
## 9 18673 4159 Google… gaborcs… sleep… 2.08e+1 1.73e+0 2.39e8 1.91e12 2025-04-28 06:47:44 <ps_handl>
## 10 18257 4159 Google… gaborcs… sleep… 2.11e+1 2.85e+0 2.02e8 1.91e12 2025-04-28 06:31:40 <ps_handl>
## 11 17380 4159 Google… gaborcs… sleep… 1.25e+1 1.50e+0 1.76e8 1.91e12 2025-04-28 05:48:24 <ps_handl>
## 12 16963 4159 Google… gaborcs… sleep… 4.73e+2 6.83e+1 5.52e8 1.91e12 2025-04-28 05:31:43 <ps_handl>
## 13 4214 4159 Google… gaborcs… sleep… 4.88e+0 1.34e+0 1.34e8 1.91e12 2025-04-26 23:27:03 <ps_handl>
## 14 4199 4159 Google… gaborcs… sleep… 1.26e+2 1.08e+1 3.45e8 1.91e12 2025-04-26 23:26:59 <ps_handl>
## 15 4176 4159 Google… gaborcs… sleep… 2.38e+2 2.31e+2 1.23e8 4.55e11 2025-04-26 23:26:58 <ps_handl>
## 16 4175 4159 Google… gaborcs… sleep… 2.05e+3 1.09e+3 1.35e8 4.56e11 2025-04-26 23:26:58 <ps_handl>
## 17 4159 1 Google… gaborcs… sleep… 1.21e+3 3.79e+2 6.00e8 4.56e11 2025-04-26 23:26:54 <ps_handl>
## 18 22365 22350 qemu-s… gaborcs… sleep… 1.26e+4 1.65e+3 1.58e8 4.26e11 2025-04-24 10:02:15 <ps_handl>
## 19 1726 1 Spotli… gaborcs… sleep… 1.64e+2 4.42e+1 1.47e8 4.25e11 2025-04-22 14:34:30 <ps_handl>
## 20 1644 1 iTerm2 gaborcs… sleep… 6.32e+3 1.32e+3 3.87e8 4.23e11 2025-04-22 14:34:22 <ps_handl>
Top 3 memory consuming processes:
ps() |>
top_n(3, rss) |>
arrange(desc(rss))## # A data frame: 3 × 11
## pid ppid name username status user system rss vms created ps_handle
## <int> <int> <chr> <chr> <chr> <dbl> <dbl> <dbl> <dbl> <dttm> <I<list>>
## 1 4159 1 Google Chr… gaborcs… sleep… 1211. 379. 6.00e8 4.56e11 2025-04-26 23:26:54 <ps_handl>
## 2 16963 4159 Google Chr… gaborcs… sleep… 473. 68.3 5.52e8 1.91e12 2025-04-28 05:31:43 <ps_handl>
## 3 1644 1 iTerm2 gaborcs… sleep… 6316. 1322. 3.87e8 4.23e11 2025-04-22 14:34:22 <ps_handl>
Top 3 processes which consumed the most CPU time:
ps() |>
mutate(cpu_time = user + system) |>
top_n(3, cpu_time) |>
arrange(desc(cpu_time)) |>
select(pid, name, cpu_time)## # A data frame: 3 × 3
## pid name cpu_time
## <int> <chr> <dbl>
## 1 22365 qemu-system-aarch64 14269.
## 2 1644 iTerm2 7639.
## 3 4175 Google Chrome Helper (GPU) 3140.
Please note that the ps project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.
MIT © RStudio