backup script error with could not connect to database

hello expert,
I had to do a backup on replication master-slave servers.  I also have asked this question before, but  I don't understand why I followed the information and same scripting to run on the replication servers and didn't work.  I can run pg_dumpall successful but not with the script.  Would you please tell me what's wrong and what need to correct the error?
my replication server (master) pg_hba.conf
# "local" is for Unix domain socket connections onlylocal   all   all                                                     peerhost   all    all                     192.168.2.0/24        trust# IPv4 local connections:host   all   all                       127.0.0.1/32           indentlocal  all   postgres                                            trusthost   all   power_user         0.0.0.0/0               md5host   all   other_user          0.0.0.0/0                md5
host   all   storageLoader    0.0.0.0/0                md5
# IPv6 local connections:host   all   all                        ::1/128                  indent#allow replication connections from localhost, by a user with the replication priviledgelocal   replication   all                                        trusthost   replication   all         127.0.0.1/32           trusthost   replicaiton   all         ::1/128                    trusthost   replication   replicauser     masterIP/32  trusthost   replicaiton   replicauser     slaveIP/32     trust
from the postgres prompt I can connect to each database
#psql -d template0 -U postgres
template0-#
#psql -d template1 -U postgres
template1-#

#psql -d pscidr -U postgres
pscidr-#
#psql -d postgres -U postgres
postgres-#

when I run the script as postgres os, I don't see the error but the only global.sql backup but nothing in it, 0 byte (blank) sql script.
when I run as root su -c postgres /path/pg_backup.sh > pgbackup.log, I get below:

Performing globals backup:Globals backuppg_dumpall: could not connect to database "template1":FATAL: Ident authentication failed for user "postgres" fro globals backup.  
Performing schema-only backup:psql:FATAL: Ident authentication failed for user "postgres"the following databases were matched for schema-only backup:
performing full backup:psql:FATAL: Ident authentication failed for user "postgres"

I can run pg_dumpall > postgresdump.sql as postgres user os fine will all the databases backup
pg_backup.sh and pg_backup.config attachment.
v/r,
Bach-Nga

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