CODEWITHSUNDEEP
rsystem2
ixodid
ixodid

Reputation: 2400

Add stdout = TRUE to R's system2 command and receive warning. Why?

I require the number of Firefox processes running on Linux (Ubuntu) be stored in a variable in an R script. By itself the system2 command I use seems to work. However, when I add stdout = TRUE to capture the info in a character vector I get a warning. Why the warning?

system2(command = "ps", args = "aux | grep [f]irefox -c")
# 0

system2(command = "ps", args = "aux | grep [f]irefox -c", stdout = TRUE)

Warning message:
In system2(command = "ps", args = "aux | grep [f]irefox -c", stdout = TRUE) :
  running command ''ps' aux | grep [f]irefox -c' had status 1

Upvotes: 2

Views: 200

Answers (1)

kangaroo_cliff
kangaroo_cliff

Reputation: 6222

Use ef instead of aux as the argument to ps. aux for BSD and ef and variants for standard syntex, as per man ps.

system2('ps', '-ef | grep [f]irefox -c', stdout = TRUE)
[1] "12"

Upvotes: 1

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