Hello,
Here are two ways.
1. system2 returns the return value of the shell command so if Java is
installed, it should return 0. In the first call it's 'java' (lowercase
j), in the second 'Java' (uppercase J).
java <- system2('java', '-version')
java
#[1] 0
Java <- system2('Java', '-version')
Java
#[1] 127
2.
Another way is to redirect the shell output to file. In this case I'm
redirecting to a temp file. Then, readLines from that file.
tmpfile <- tempfile()
if(!dir.exists(dirname(tmpfile))) dir.create(dirname(tmpfile))
system2('java', '-version', '>', tmpfile)
readLines(tmpfile)
unlink(tmpfile) # final cleanup
Hope this helps,
Rui Barradas
Às 16:51 de 09/11/19, Dennis Fisher escreveu:
R 3.6.3
OSX and Windows
Colleagues
I want to identify if Java is installed on a particular computer.
When I execute
Java -version
in a terminal (OSX), but not in R, there are two outcomes:
Java installed yields:
java version "13.0.1" 2019-10-15
Java(TM) SE Runtime Environment (build 13.0.1+9)
Java HotSpot(TM) 64-Bit Server VM (build 13.0.1+9, mixed mode, sharing)
Java not installed yields:
No Java runtime installed
I assume that there are comparable outputs in Windows.
I would like to capture this output in R using the system command, then search
for “No Java runtime installed” )or the correponding text in Windows).
I execute something like:
CAPTURE <- system("Java -version", intern=TRUE, ignore.stderr=FALSE,
ignore.stdout=FALSE)
(with various permutations of TRUE/FALSE for the options) but I cannot capture
what is displayed on the console.
I have also tried “system2” with various TRUE/FALSE permutations without
success.
Any clever ideas?
Dennis
Dennis Fisher MD
P < (The "P Less Than" Company)
Phone / Fax: 1-866-PLessThan (1-866-753-7784)
www.PLessThan.com
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
