(I reported the test failure mentioned below to R-help but was advised that this list is the right one to address the issue; in the meantime I investigated the matter somewhat more closely, including searching recent R-devel postings, since I haven't been following this list.)
Last May there were two reports here of problems with Sys.timezone, one where the zoneinfo directory is in a nonstandard location (https://stat.ethz.ch/pipermail/r-devel/2017-May/074267.html) and the other where the system lacks the file /etc/localtime (https://stat.ethz.ch/pipermail/r-devel/2017-May/074275.html). My system exhibits a third case: it lacks /etc/timezone and does not set TZ systemwide, but it does have /etc/localtime, which is a copy of, rather than a symlink to, a file under zoneinfo. On this system Sys.timezone() returns NA and the Sys.timezone test in reg-tests-1d fails. However, on my system I can get the (abbreviated) timezone in R by using as.POSIXlt, e.g. as.POSIXlt(Sys.time())$zone. If Sys.timezone took advantage of this, e.g. as below, it would be useful on such systems as mine and the regression test would pass. my.Sys.timezone <- function (location = TRUE) { tz <- Sys.getenv("TZ", names = FALSE) if (!location || nzchar(tz)) return(Sys.getenv("TZ", unset = NA_character_)) lt <- normalizePath("/etc/localtime") if (grepl(pat <- "^/usr/share/zoneinfo/", lt) || grepl(pat <- "^/usr/share/zoneinfo.default/", lt)) sub(pat, "", lt) else if (lt == "/etc/localtime") if (!file.exists("/etc/timezone")) return(as.POSIXlt(Sys.time())$zone) else if (dir.exists("/usr/share/zoneinfo") && { info <- file.info(normalizePath("/etc/timezone"), extra_cols = FALSE) (!info$isdir && info$size <= 200L) } && { tz1 <- tryCatch(readBin("/etc/timezone", "raw", 200L), error = function(e) raw(0L)) length(tz1) > 0L && all(tz1 %in% as.raw(c(9:10, 13L, 32:126))) } && { tz2 <- gsub("^[[:space:]]+|[[:space:]]+$", "", rawToChar(tz1)) tzp <- file.path("/usr/share/zoneinfo", tz2) file.exists(tzp) && !dir.exists(tzp) && identical(file.size(normalizePath(tzp)), file.size(lt)) }) tz2 else NA_character_ } One problem with this is that the zone component of as.POSIXlt only holds the abbreviated timezone, not the Olson name. I don't know how to get the Olson name using only R functions, but maybe it would be good enough to return the abbreviated timezone where possible, e.g. as above. (On my system I can get the Olson name of the timezone in R with a shell pipeline, e.g.: system("find /usr/share/zoneinfo/ -type f | xargs md5sum | grep $(md5sum /etc/localtime | cut -d ' ' -f 1) | head -n 1 | cut -d '/' -f 5,6"), but the last part of this is tailored to my configuration and the whole thing is not OS-neutral, so it isn't suitable for Sys.timezone.) Steve Berman ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
