read-line

(read-line &optional stream eof-error-p eof-value recursive-p)

Reads one line of text and returns it as a string with the trailing newline removed (only a line feed ends a line, and one carriage return just before it -- or before the end of input -- is dropped, so a CR alone stays in the line, and CRLF-terminated input such as HTTP over a rontolisp:tcp-connect socket reads as plain lines). With no argument it reads from standard input; given a stream opened by open or with-open-file it reads the next line from that stream. At end of input it returns eof-value (default nil) rather than signalling: eof-error-p defaults to nil here, where CL defaults it to t, and a true one signals end-of-file. recursive-p is accepted and ignored: it only matters to a reader macro's recursive read. The second value, missing-newline-p, is true when end of input -- not a newline -- ended the line, and true beside eof-value at end of input, as in CL; it is answered on every backend, through a Gray stream's stream-read-line too. Works in all three backends; unlike read, it returns the raw line without parsing it as an S-expression.

(print (read-line))

Typing hello world on standard input makes read-line return the string "hello world". When the input is exhausted it returns nil, which is the usual loop-termination test when reading a file line by line.