On Sat, Apr 29, 2023 at 01:52:11AM +0200, coreyh@free.fr wrote: > $ sudo echo 123 > /root/123.txt > > It tells me "permission rejected". > > Why this sudo can't get success? Because the redirection is done by your shell before sudo is executed. See <https://mywiki.wooledge.org/BashPitfalls#pf53> for suggestions, but basically you're looking at variants of: sudo sh -c 'echo 123 > /root/123.txt'