Problem on SQLplus command ""bash: sqlplus: command not found""

Hi all,
i face an error related to my server ""it's running server"" when i use sqlplus command

[oracle@srv1 bin]$ sqlplus
bash: sqlplus: command not found

the data base is up and running i just need to access the sqlplus to import the dump file as a daily backup.

i already check the directory '/u01/app/oracle/product/11.2.0/db_1/bin' and test sqlplus but the same error exist

appreciate any help

Thanks in advanced

---------- Post updated at 06:36 AM ---------- Previous update was at 06:35 AM ----------

also i try to change the permission 777 for sqlplus