While perusing various termios(3) and termios(4) manpages, I noticed the
following inconsistency for ONLRET. FreeBSD and NetBSD say this:
If ONLRET is set, the NL character is assumed to do the carriage-return
function; the column pointer will be set to 0.
OpenBSD says this:
If ONLRET is set, NL also performs CR on output, and reset current column
to 0.
POSIX says this:
NL performs CR function.
The current Linux manpage says this (!):
Don't output CR.
Here's a snippet that demonstrates Linux's behavior (tl;dr it's just like the
other operating systems):
$ stty -icanon -onlcr -icrnl -echo onlret onocr; cat
this is some text (^J pressed)
and some more (^M pressed before additional text)
The first flags (-icanon -onlcr -icrnl -echo), combined with cat, ensure that
our keys are sent directly back to the terminal emulator without any translation
or buffering. The last two (ONLRET and ONOCR) are the important ones: ONLRET
makes Linux think that the cursor is at column 0 after the ^J, and ONOCR makes
Linux ignore the following ^M.
---
man3/termios.3 | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/man3/termios.3 b/man3/termios.3
index c11937458..20641f14d 100644
--- a/man3/termios.3
+++ b/man3/termios.3
@@ -203,7 +203,9 @@ Map CR to NL on output.
Don't output CR at column 0.
.TP
.B ONLRET
-Don't output CR.
+The NL character is assumed to do the carriage-return function;
+the kernel's idea of the current column is set to 0
+after both NL and CR.
.TP
.B OFILL
Send fill characters for a delay, rather than using a timed delay.
--
2.34.0
---
man3/termios.3 | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/man3/termios.3 b/man3/termios.3
index c11937458..20641f14d 100644
--- a/man3/termios.3
+++ b/man3/termios.3
@@ -203,7 +203,9 @@ Map CR to NL on output.
Don't output CR at column 0.
.TP
.B ONLRET
-Don't output CR.
+The NL character is assumed to do the carriage-return function;
+the kernel's idea of the current column is set to 0
+after both NL and CR.
.TP
.B OFILL
Send fill characters for a delay, rather than using a timed delay.
--
2.34.1
