There is a pretty comprehansive answer at https://unix.stackexchange.com/questions/364/allow-setuid-on-shell-scripts Bottom line is that there are two main points against it: A race condition between when the Kernel opens the file to find which interpreter it should execute and when the interpreter opens the file to read the script. Shell scripts which execute many external programs without … Read more
Since the suid bit on executables only changes the effective UID (EUID) the executable will run as, and not the real UID (RUID) which getuid() returns, and in addition to the restriction on suid interpreted scripts (any executable beginning with “#!“), some shells like bash as an extra safety measure will set the EUID back … Read more
Since you mentioned a daemon, I can conclude that you are running on a Unix-like operating system. This matters, because how to do this depends on the kind operating system. This answer applies only to Unix, including Linux, and Mac OS X. Define a function that will set the gid and uid of the running … Read more