postgres@debian-10-3-vm2:~$ cat 111.txt 
1
2
3
4
5
postgres@debian-10-3-vm2:~$ for db in $(cat 111.txt); do echo $db -- a; done
1 -- a
2 -- a
3 -- a
4 -- a
5 -- a
postgres@debian-10-3-vm2:~$ выход
user1@debian-10-3-vm2:~$ sudo -i -u postgres  bash -c 'for db in $(cat 111.txt); do echo $db -- a; done'
-- a
-- a
-- a
-- a
-- a
user1@debian-10-3-vm2:~$ 

postgres@debian-10-3-vm2:~$ for db in $(cat 111.txt); do echo $db -- a; done
1 -- a
2 -- a
3 -- a
4 -- a
5 -- a
postgres@debian-10-3-vm2:~$ выход
user1@debian-10-3-vm2:~$ sudo -i -u postgres bash -c "for db in $(cat /var/lib/postgresql/111.txt); do echo $db -- a; done"
-- a
user1@debian-10-3-vm2:~$ 

user1@debian-10-3-vm2:~$ sudo -i -u postgres bash -c 'for db in $(cat 111.txt); do echo ${db} ; done'
1
2
3
4
5