[root@vps152 pga]# su postgres -c pg_ctl restart
bash: /root/.bashrc: Permission denied
pg_ctl: no operation mode specified
Try 'pg_ctl --help' for more information.
[root@vps152 pga]# su postgres -c pg_ctl --help
Usage: su [OPTION]... [-] [USER [ARG]...]
Change the effective user id and group id to that of USER.
-, -l, --login make the shell a login shell
-c, --commmand=COMMAND pass a single COMMAND to the shell with -c
-f, --fast pass -f to the shell (for csh or tcsh)
-m, --preserve-environment do not reset environment variables
-p same as -m
-s, --shell=SHELL run SHELL if /etc/shells allows it
--help display this help and exit
--version output version information and exit
A mere - implies -l. If USER not given, assume root.
Report bugs to <bug-coreutils@gnu.org>.