[R] Linux System Function

[Ryan Garner]

How do I pass a filename as an argument to the system command to count the
number of records in that file? I only know how to do it by hardcoding it.

HARDCODING EXAMPLE
> test <- matrix(1:20,ncol=5)
> write(x = test,file = "test.txt")
> records <- as.numeric(system("cat test.txt | wc -l",intern = TRUE))
> records
[1] 4

??? NON-HARCODING EXAMPLE ???
> file = "test.txt"
> records <- as.numeric(system("cat file | wc -l",intern = TRUE))
cat: file: No such file or directory
> records <- as.numeric(system("cat" test.txt "| wc -l",intern = TRUE))
Error: unexpected symbol in "records <- as.numeric(system("cat" test.txt"

TFYH

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