How do I list tnsnames

Is there any easy way to list out all the available tnsnames in my system via command line?

Whenever I need to find out a tnsname, I just simply search for the tnsnames.ora file with tnsping command and open it in a text editor to scan through. Then subsequently run tnsping [tnsname] to check the connection health. I was thinking if there's any easy command like tnslist or tns -l to list out all the tnsnames but I couldn't find such.

Assuming that you have such a tnsnames.ora file :

DB01 = 
    (DESCRIPTION = 
        (FAILOVER=off) 
        (LOAD_BALANCE=off) 
          (ADDRESS = (PROTOCOL = TCP)(HOST = db01-vip)(PORT = 1521)) 
         (CONNECT_DATA = 
             (SERVER = DEDICATED) 
             (SERVICE_NAME = mydb1) 
         ) 
     ) 

DB02 = 
    (DESCRIPTION = 
        (FAILOVER=off) 
        (LOAD_BALANCE=off) 
          (ADDRESS = (PROTOCOL = TCP)(HOST = db02-vip)(PORT = 1531)) 
         (CONNECT_DATA = 
             (SERVER = DEDICATED) 
             (SERVICE_NAME = mydb2) 
         ) 
     ) 

edit your .profile or .bash_profile like this:

[oracle@mydb12c~ ] vi .bash_profile

ORACLE_HOME=/u01/app/oracle/product/12.1.0.2/dbhome_1; export ORACLE_HOME
...
alias lstns="sed -n '/DESCR/{x;p;d;}; x' $ORACLE_HOME/network/admin/tnsnames.ora | sed "s/=/${s}/""
echo 'lstns : tnsnames.ora listing'

[oracle@mydb12c~ ] . .bash_profile

lstns : tnsnames.ora listing

[oracle@mydb12c~ ] lstns

  DB01 
  DB02