[PATCH v2] system.3: Document bug and workaround when the command name starts with a hypen

[Alejandro Colomar <alx.manpages@gmail.com>]

man-pages bug: 211029
 https://bugzilla.kernel.org/show_bug.cgi?id=211029

Complete workaround
(it was too long for the page, but it may be useful here):

......

$ sudo ln \-s \-T /usr/bin/echo /usr/bin/\-echo;
$ cc -o system_hyphen -x c - ;

int
main(void)
{
    system(" -echo Hello world!");
    exit(EXIT_SUCCESS);
}

$ ./system_hyphen;
Hello world!

Reported-by: Ciprian Dorin Craciun <ciprian.craciun@gmail.com>
Cc: Florian Weimer <fweimer@redhat.com>
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
 man3/system.3 | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/man3/system.3 b/man3/system.3
index 753d46f7d..ead35ab30 100644
--- a/man3/system.3
+++ b/man3/system.3
@@ -255,6 +255,26 @@ are not executed.
 Such risks are especially grave when using
 .BR system ()
 from a privileged program.
+.SH BUGS
+.\" [BUG 211029](https://bugzilla.kernel.org/show_bug.cgi?id=211029)
+.\" [Glibc bug](https://sourceware.org/bugzilla/show_bug.cgi?id=27143)
+.\" [POSIX bug](https://www.austingroupbugs.net/view.php?id=1440)
+If the command name starts with a hyphen,
+.BR sh (1)
+interprets the command name as an option,
+and the behavior is undefined.
+(See the
+.B \-c
+option to
+.BR sh (1).)
+To work around this problem,
+prepend the command with a space as in the following call:
+.PP
+.RS 4
+.EX
+    system(" \-unfortunate\-command\-name");
+.EE
+.RE
 .SH SEE ALSO
 .BR sh (1),
 .BR execve (2),
-- 
2.29.2