Code:
example, look the TRIM()


LOAD DATA
INFILE '/tmp/hist_ora_alert.dat'
APPEND
INTO TABLE TUHCDM10.hist_ora_alert
FIELDS TERMINATED BY '@'
TRAILING NULLCOLS
(
   NUM_LINEA                        DECIMAL EXTERNAL,
   NOM_ORACLE_SID                   CHAR,
   FEC_ALERT                        DATE "DY MON DD HH24:MI:SS YYYY",
   FEC_BBDD                         SYSDATE,
   COD_ERROR                        DECIMAL EXTERNAL "TRIM(:COD_ERROR)",
   ES_ERROR                        CHAR NULLIF(ES_ERROR=BLANKS) "TRIM(:ES_ERROR)",
   DES_OBSERVACION                  CHAR NULLIF(DES_OBSERVACION=BLANKS)
)
I am clueless coz I dont know what do you want