Conditional select if exists - select

Question

I would like to have SQL code to validate if table [grlf_lig] exists than select fields, how can I do it on informix?
I use sheel code for the validation but it is slow, because it have to record files on disk and make validations.
dbaccess sysmaster <<EOF > /dev/null 2> /dev/null
set isolation to dirty read;
unload to '$TMPFILE' delimiter "|"
select x0.sid,
x0.username,
x0.hostname,
x1.sqs_dbname,
dbinfo("UTC_TO_DATETIME",x0.connected) AS conn_dt
from
sysmaster:"informix".syssessions x0,
sysmaster:"informix".syssqlstat x1,
sysmaster:"informix".sysnetworkio n
where ( x0.sid = x1.sqs_sessionid ) and hostname is not NULL and
trim(hostname) <> ''
and trim(hostname) <> '-' AND sqs_dbname NOT LIKE 'sys%' AND sqs_dbname <>
'-' AND n.sid = x0.sid
EOF
for I in `cat $TMPFILE`; do
SID=`echo $I | awk -F'|' '{print $1}'`
BD=`echo $I | awk -F'|' '{print $4}'`
echo "" > $FILE
dbaccess $BD <<EOF > /dev/null 2> /dev/null
set isolation to dirty read;
unload to "$FILE" delimiter '|'
select first 1 sid_f_lig, max(dtlogin_f_lig), winuser_f_lig, tty_f_lig,
cod_capli from grlf_lig where
( sid_f_lig = '$SID' and dtlogout_f_lig is null )
group by sid_f_lig, winuser_f_lig, tty_f_lig, cod_capli
EOF
if [ -s $FILE ]; then
cat $FILE >> $FILE1
fi
done
I would like to get results fast, because it takes long times to get results.