Error description

$ sqlplus/as sysdba
-bash: sqlplus: command not found

Treatment method

View environment.bash_ Profile configuration

$ find -name .bash_profile
./.bash_profile
$ pwd
/home/oracle
$ vi .bash_profile
# .bash_profile

# Get the aliases and functions
if [ -f ~/.bashrc ]; then
        . ~/.bashrc
fi

# User specific environment and startup programs

PATH=$PATH:$HOME/.local/bin:$HOME/bin

export PATH

#add by rui on 20210715
export ORACLE_BASE=/oracle/app
export ORACLE_HOME=$ORACLE_BASE/oracle/product/12.1.0/dbhome_1 --Configuration error, change to [1]
export ORACLE_SID=rui1
export PATH=$HOME/bin:$ORACLE_HOME/bin:$PATH
export LD_LIBRARY_PATH=$ORACLE_HOME/lib:/usr/lib

[1] export ORACLE_ HOME=$ORACLE_ BASE/product/12.1.0/dbhome_ one

Open a new window and enter the command again

$ sqlplus/as sysdba

SQL*Plus: Release 12.1.0.2.0 Production on Thu Jul 15 04:42:11 2021

Copyright (c) 1982, 2014, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

SQL>

It can be seen that the problem has been successfully solved
the reason for this error is $oracle_ Home configuration error.