When using RMAN catalog it is preferred to use backup script stored in catalog. It is best if scripts can be reused for different retention.
You can use variables in RMAN script this way:
CREATE global script global_backup_full_database comment 'backup full of database. Parameter sysdate+n,tag db, tag archivelog' { allocate channel c1 TYPE SBT_TAPE PARMS 'BLKSIZE=1048576,SBT_LIBRARY=/usr/lib/ddbda/libddboostora.so, ENV=(CONFIG_FILE=/opt/ddbda/config/oracle_ddbda.cfg)' FORMAT '%d_%U'; backup AS backupset DATABASE filesperset 1 keep until TIME '&1' tag &2; backup AS backupset archivelog ALL DELETE INPUT filesperset=1 keep until TIME '&1' tag &3; }