Could not open parameter file '/opt/oracle/product/10.2/db_1/dbs/initorcl.ora__oracle

Sql> Startup
Ora-01078:failure in processing system parameters
Lrm-00109:could not open parameter file '/opt/oracle10g/product/10.2/db_1/dbs/initora10g.ora '

Find the file, it does not exist. It is estimated that the illegal shutdown was caused.

This is because in Oracle9i and oracle10g, Oracle will use SPFile to start the database by default, and this error will occur if SPFile does not exist.

Workaround 1 (verified):
Copy the init.ora.012009233838 form of the $oracle_base/admin/database name/pfile directory to the $oracle_home/dbs directory Initoracle.ora. (Note: Oracle in Initoracle.ora is your instance name, that is, mine is Initora10g.ora)

[Root@localhost dbs]# cp init.ora.721200911530 $ORACLE _home/dbs/initora10g.ora

Then continue to switch to the Oracle account, connect to Sqlplus, run startup, and may appear:

This is because there is no permission,

[Root@localhost dbs]# chmod-r 775 Initora10g.ora
Continue startup

Success.