The O_NONBLOCK flag has been removed since Linux 5.6 and this patch states this change in man page. The commit that introduce this change in the Linux kernel is 30c08efec888 ("random: make /dev/random be almost like /dev/urandom") Signed-off-by: GUO Zihua <guozihua@xxxxxxxxxx> --- man4/random.4 | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/man4/random.4 b/man4/random.4 index bea860e7f0d7..5b2094931449 100644 --- a/man4/random.4 +++ b/man4/random.4 @@ -68,7 +68,12 @@ high quality randomness, and can afford indeterminate delays. .PP When the entropy pool is empty, reads from \fI/dev/random\fP will block until additional environmental noise is gathered. -If +Since Linux 5.6, the +.B O_NONBLOCK +flag is removed as +.I /dev/random +will no longer block except during +early boot process. In eariler versions, if .BR open (2) is called for .I /dev/random -- 2.36.0