readLines {base} | R Documentation |
Read some or all text lines from a connection.
readLines(con = stdin(), n = -1L, ok = TRUE, warn = TRUE, encoding = "unknown")
con |
a connection object or a character string. |
n |
integer. The (maximal) number of lines to read. Negative values indicate that one should read up to the end of input on the connection. |
ok |
logical. Is it OK to reach the end of the connection before
n > 0 lines are read? If not, an error will be generated. |
warn |
logical. Warn if a text file is missing a final EOL. |
encoding |
encoding to be assumed for input strings. It is
used to mark character strings as known to be in
Latin-1 or UTF-8: it is not used to re-encode the input. To do the
latter, specify the encoding as part of the connection con or
via options(encoding=) : see the example under
file .
|
If the con
is a character string, the function calls
file
to obtain a file connection which is opened for
the duration of the function call.
If the connection is open it is read from its current position. If it
is not open, it is opened in "rt"
mode for the duration of
the call and then closed again.
If the final line is incomplete (no final EOL marker) the behaviour depends on whether the connection is blocking or not. For a non-blocking text-mode connection the incomplete line is pushed back, silently. For all other connections the line will be accepted, with a warning.
Whatever mode the connection is opened in, any of LF, CRLF or CR will be accepted as the EOL marker for a line.
A character vector of length the number of lines read.
The elements of the result have a declared encoding if encoding
is
"latin1"
or "UTF-8"
,
The default connection, stdin
, may be different from
con = "stdin"
: see file
.
connections
, writeLines
, readBin
,
scan
cat("TITLE extra line", "2 3 5 7", "", "11 13 17", file="ex.data", sep="\n") readLines("ex.data", n=-1) unlink("ex.data") # tidy up ## difference in blocking cat("123\nabc", file = "test1") readLines("test1") # line with a warning con <- file("test1", "r", blocking = FALSE) readLines(con) # empty cat(" def\n", file = "test1", append = TRUE) readLines(con) # gets both close(con) unlink("test1") # tidy up