| readLines {base} | R Documentation |
Read Text Lines from a Connection
Description
Read text lines from a connection.
Usage
readLines(con = stdin(), n = -1, ok = TRUE)
Arguments
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 the connection. |
ok |
logical. Is it OK to reach the end of the connection before
|
Details
If the con is a character string, the functions call
file to obtain an 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 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 blocking text-mode connection (or a non-text-mode connection) the line will be accepted, with a warning. For a non-blocking text-mode connection the incomplete line is pushed back, silently.
Value
A character vector of length the number of lines read.
See Also
connections, writeLines,
scan
Examples
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