Sql*Plus ERROR: ORA-12154: TNS:could not resolve the connect identifier specified
When you use sqlplus userName/myPassword@"(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=asdasdasd.com)(PORT=1524))(CONNECT_DATA=(SID=AARCER1)))" then you don't need any tnsnames.ora file. 

Your entry in tnsnames.ora file should be like this:

AARCER1 = (DESCRIPTION=
     (ADDRESS=(PROTOCOL=tcp)(HOST= asdasdasd.com)(PORT=1524))
    (CONNECT_DATA =
      (SID = AARCER1)
    )
  )


Then you can shorten your command to sqlplus userName/myPassword@AARCER1 - that is the purpose of tnsnames.ora.

In order to use tnsnames.ora you must also have file sqlnet.ora.
There you need an entry like this:

NAMES.DIRECTORY_PATH = (TNSNAMES)


However, default value is NAMES.DIRECTORY_PATH=(tnsnames, ldap, ezconnect), so actually you can skip it.

Set environment variable TNS_ADMIN to location of these files, i.e. 

export TNS_ADMIN=/usr/lib/oracle/11.2/client64/network/admin