Subject: bug#29390: chmod man page - clear setuid/setgid with numerical value

From: Oliver Isaac <[email-masked]>
Date: Tue, 21 Nov 2017 20:46:33 -0600

Hello,

There is an incorrect assertion made in the chmod man page:

Under the setuid/setgid header it says, "you can set (but not clear) the bits with a numeric mode"

This is not entirely true. If you prefix your numeric mode with a 0 then it will work:

e.g.:

touch myfile
chmod 644 myfile
ls -l myfile
chmod g+s myfile
Is -l myfile
chmod 00644 myfile
is -l myfile

This simple test shows that you can clear the uid/gid bits with numeric mode which is especially useful in scripts.

An update to the man page to clarify this would be helpful. 

Thanks,
Oliver