[Rd] showConnections() does not show closed (or non-opened) connections though help says so
Jens Oehlschlägel
joehl@web.de
Wed, 20 Dec 2000 13:42:43 +0100
help on showConnections explains parameter
all logical: if true all connections, including closed ones and the standard ones are displayed. If false only open user-created connections are included.
but
> # create a file
> cat("TITLE extra line", "2 3 5 7", "", "11 13 17", file="ex.data",
+ sep="\n")
> showConnections(all=TRUE)
class description mode text isopen can read can write
0 "stdin" "terminal" "r" "text" "opened" "yes" "no"
1 "stdout" "terminal" "w" "text" "opened" "no" "yes"
2 "stderr" "terminal" "w" "text" "opened" "no" "yes"
>
> con <- file("ex.data")
> showConnections(all=TRUE)
class description mode text isopen can read can write
0 "stdin" "terminal" "r" "text" "opened" "yes" "no"
1 "stdout" "terminal" "w" "text" "opened" "no" "yes"
2 "stderr" "terminal" "w" "text" "opened" "no" "yes"
> # here the connection (existing? but not-opened) is not listend
>
> open(con)
> showConnections(all=TRUE)
class description mode text isopen can read can write
0 "stdin" "terminal" "r" "text" "opened" "yes" "no"
1 "stdout" "terminal" "w" "text" "opened" "no" "yes"
2 "stderr" "terminal" "w" "text" "opened" "no" "yes"
3 "ex.data" "file" "r" "text" "opened" "yes" "no"
>
> close(con)
> showConnections(all=TRUE)
class description mode text isopen can read can write
0 "stdin" "terminal" "r" "text" "opened" "yes" "no"
1 "stdout" "terminal" "w" "text" "opened" "no" "yes"
2 "stderr" "terminal" "w" "text" "opened" "no" "yes"
>
> readLines("ex.data", n=-1)
[1] "TITLE extra line" "2 3 5 7" "" "11 13 17"
> showConnections(all=TRUE)
class description mode text isopen can read can write
0 "stdin" "terminal" "r" "text" "opened" "yes" "no"
1 "stdout" "terminal" "w" "text" "opened" "no" "yes"
2 "stderr" "terminal" "w" "text" "opened" "no" "yes"
> # here we don't know whether showConnections() does not show a connection created and opened by readLine()
> # or whether readLines() did also close the connection
Regards
Jens Oehlschlägel
--please do not edit the information below--
Version:
platform = i386-pc-mingw32
arch = x86
os = Win32
system = x86, Win32
status =
major = 1
minor = 2.0
year = 2000
month = 12
day = 15
language = R
Windows NT 4.0 (build 1381) Service Pack 6
Search Path:
.GlobalEnv, package:ctest, Autoloads, package:base
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