Unlock Informix table

First, get the sessid using the following sql:

select unique
dbsname db,
tabname table,
case
when type="S" then "shared lock"
when type="IS" then "intent shared lock"
when type="SIX" then "shared intent excl lock"
when type="XS" then "shared key value by RR"
when type="IX" then "intent excl lock"
when type="X" then "exclusive lock"
when type="XR" then "excl key value by RR"
when type="U" then "update lock"
when type="B" then "byte lock"
else
"unknown lock type"
end lock_type,
lpad(owner,5) ses_id,
lpad(waiter,5) wait_id
from sysmaster:syslocks
where tabname != 'sysdatabases';

And check the table concerned by the lock. Using its session id, you can now unlock it with:

>onmode -z <sess_id>

Thanks to this thread