$ locale 
LANG=en_US.UTF-8
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=

$ /opt/fb25sc/bin/isql localhost/3252:/var/db/fb25/utf8fb25.fdb  -ch utf8 
SQL> set list on; select a.mon$character_set_id,r.rdb$character_set_name from mon$attachments a join rdb$character_sets r on  a.mon$character_set_id = r.rdb$character_set_id ;

MON$CHARACTER_SET_ID            4
 RDB$CHARACTER_SET_NAME          UTF8    

SQL> show database;
Database: localhost/3252:/var/db/fb25/utf8fb25.fdb
        Owner: SYSDBA
PAGE_SIZE 16384
Number of DB pages allocated = 808
Sweep interval = 20000
Forced Writes are ON
Transaction - oldest = 64
Transaction - oldest active = 65
Transaction - oldest snapshot = 65
Transaction - Next = 69
ODS = 11.2
 Default Character set: UTF8 
SQL> show table book; -- это я сюда затолкать хочу много всякого UTF8-текста.
TEXT                            VARCHAR(80) Nullable
LANG                            VARCHAR(3) Nullable

ISQL Version: LI-V2.5.4.26821 Firebird 2.5
Server version:
Firebird/linux AMD64 (access method), version "LI-V2.5.4.26821 Firebird 2.5"
Firebird/linux AMD64 (remote server), version "LI-V2.5.4.26821 Firebird 2.5/tcp (oel64)/P12"
Firebird/linux AMD64 (remote interface), version "LI-V2.5.4.26821 Firebird 2.5/tcp (oel64)/P12"

BufferedReader fr = new BufferedReader(new InputStreamReader(new FileInputStream(inpFile), "utf8"));
BufferedWriter fw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(outFile), "utf8"));

INSERT record 1 of table BOOK
 New data:
	TEXT has type 3 and length 322
		charset = 4, value = 'Řř'
	LANG has type 3 and length 5
		charset = 0, value = 'CZE'
>>>>>>> Release savepoint 2 >>>>>>>