According to the manual, system() splits output lines into
8096-char chunks; under UNIX, actually seems to return 8094
chars, and drop the 8095th. Spot missing digits in:
x2 <-
system("perl -e 'print \"0123456789\"x10000'",
intern=T)
Looks like a bug in the code to remove newlines at
src/unix/sys-unix.c:218 -- fgets() reads size-1 characters
and adds null, so strlen(buf)<size always true. Testing for
'\n' explicitly is probably better (deals with 8094 chr + \n
case) -- it turns out the win32 code already does this
anyway. (IIRC the read>0 condition in the win32 code would
be redundant but I copied it anyway to be safe.)
Anyway, rather trivial diff below. Both manpages should
probably say 8095 rather than 8096, I think.
Mark <><
Index: library/base/man/unix/system.Rd
==================================================================RCS file:
/cvs/R/src/library/base/man/unix/system.Rd,v
retrieving revision 1.2
diff -u -r1.2 system.Rd
--- library/base/man/unix/system.Rd 2002/12/08 09:50:47 1.2
+++ library/base/man/unix/system.Rd 2004/02/28 15:20:09
@@ -26,7 +26,7 @@
If \code{intern} is \code{TRUE} then \code{popen} is used to invoke the
command and the output collected, line by line, into an \R
\code{\link{character}} vector which is returned as the value of
- \code{system}. Output lines of more that 8096 characters will be split.
+ \code{system}. Output lines of more that 8095 characters will be split.
If \code{intern} is \code{FALSE} then the C function \code{system}
is used to invoke the command and the value returned by \code{system}
Index: library/base/man/windows/system.Rd
==================================================================RCS file:
/cvs/R/src/library/base/man/windows/system.Rd,v
retrieving revision 1.15
diff -u -r1.15 system.Rd
--- library/base/man/windows/system.Rd 2003/05/08 21:45:54 1.15
+++ library/base/man/windows/system.Rd 2004/02/28 15:20:09
@@ -33,7 +33,7 @@
If \code{intern = TRUE}, a character vector giving the output of the
command, one line per character string. If the command could not be
run or gives an error a \R error is generated.
- (Output ines of more that 8096 characters will be split.)
+ (Output lines of more that 8095 characters will be split.)
If \code{intern = FALSE}, the return value is a error code, given the
invisible attribute (so needs to be printed explicitly). If the
Index: unix/sys-unix.c
==================================================================RCS file:
/cvs/R/src/unix/sys-unix.c,v
retrieving revision 1.39
diff -u -r1.39 sys-unix.c
--- unix/sys-unix.c 2003/09/10 11:45:29 1.39
+++ unix/sys-unix.c 2004/02/28 15:20:15
@@ -215,7 +215,8 @@
fp = R_popen(CHAR(STRING_ELT(CAR(args), 0)), x);
for (i = 0; fgets(buf, INTERN_BUFSIZE, fp); i++) {
read = strlen(buf);
- if (read < INTERN_BUFSIZE) buf[read - 1] = '\0'; /* chop final
CR */
+ if (read>0 && buf[read-1] == '\n')
+ buf[read - 1] = '\0'; /* chop final CR */
tchar = mkChar(buf);
UNPROTECT(1);
PROTECT(tlist = CONS(tchar, tlist));