| readLines {base} | R Documentation |
Read text lines from a connection.
readLines(con = stdin(), n = -1, ok = TRUE, warn = TRUE)
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
n > 0 lines are read? If not, an error will be generated. |
warn |
logical. Warn if a text file is missing a final EOL. |
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 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.
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.
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