readLines {base}R Documentation

Read Text Lines from a Connection


Read some or all text lines from a connection.


readLines(con = stdin(), n = -1, 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 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.


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.
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.

See Also

connections, writeLines, readBin, scan


cat("TITLE extra line", "2 3 5 7", "", "11 13 17", file="",
readLines("", n=-1)
unlink("") # 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

unlink("test1") # tidy up

[Package base version 2.5.0 Index]