I'm using Ubuntu 14.04.  When logged in as root, I'm tryhing to run a command as anotehr (postgres).  However, it is failingroot@remotebox:/home/rails/myproject# su - postgres 'pg_upgradecluster 9.3 main'-su: pg_upgradecluster 9.3 main: No such file or directoryWhat am I doing wrong? 
Having trouble running a command as another user on Ubuntu
sudo;root;command;su
You're trying to pass 'pg_upgradecluster 9.3 main' to the default shell for postgres user.Depending on postgres user configuration this may mean to execute 'pg_upgradecluster 9.3 main' file in postgres PATH, and this is the reason you get a No such file or directory error.Try pass the argument as a command (-c):su - postgres -c 'pg_upgradecluster 9.3 main'as a shell:su - postgres -s /path/to/pg_upgradecluster -- 9.3 mainor to explicit choose the shell:su - postgres -s /bin/bash -- -c 'pg_upgradecluster 9.3 main'