To start Informix-SE, make sure you have at least the environment variables $INFORMIXDIR and $INFORMIXSERVER set and that you have $INFORMIXDIR/bin appended to your path. Then, simply typing
<frodo> $ dbaccess
will start a sqlexec session. Pressing enter will present a list of databases which you can open; use the arrow keys to select your desired database and press Enter.
Unless you are allowing remote access to a database host (the machine
on which the database lives), don't use sqlexecd. If you insist,
however, read on.
Because sqlexecd runs as a daemon, it must be started by root. There
are a variety of ways to accomplish this. Regardless of how you decide
to do so, $INFORMIXDIR must be set and a valid database
server name (as defined in $INFORMIXDIR/etc/sqlhosts)
must be specified as an argument to sqlexecd. See
How do I allow remote connections? for more details.
To start sqlexecd at boot time, add the following to rc.local (wherever it is located on your system). If you prefer SysV init-style scripts, of course, you may use that approach. If the previous sentence is gibberish to you, use the rc.local approach.
export INFORMIXDIR=/path/to/informix/installation
$INFORMIXDIR/lib/sqlexecd dbserver_name
To start sqlexecd at any other time, execute the same command as
above. For convenience, it is common to set $INFORMIXDIR
and $INFORMIXSERVER in /etc/profile. Many sites,
particularly large installations, use one or more global initialization
scripts to set these and other Informix-related environment variables.
When using dbaccess, there is no need to kill sqlexec directly,
because exiting dbaccess will (under normal circumstances), kill the
related sqlexec process automatically. Under abnormal
circumstances, however, I strongly recommend killing sqlexec's
parent process, such as dbaccess or the shell or compiled ESQL/C
program rather than sqlexec itself, since otherwise you may
corrupt your database. Killing the parent process will send a signal
to sqlexec and give it an opportunity to shut down normally.
This is important enough that I am going to repeat myself: Never kill a
sqlexec process unless all other solutions have failed miserably.
Doing so, particularly in a database using transaction logs, carries the
risk and likelihood of trashing your database. When transaction logging
is in effect, killing sqlexec potentially results in an incomplete
transaction that doesn't get rolled back: with sqlexec gone, any
locks in place are cleared, so other processes will continue to manipulate
the partially-updated data. You really don't want to do this!
Never kill a sqlexec process unless you have absolutely no other
alternative.
On the other hand, it is fairly harmless to kill sqlexecd. Its
only purpose is to listen on a port for incoming connections requests,
fork off a sqlexec process to service those requests, then go
back to listening for another request.
To convert Informix-SE error codes into human-readable form, use the
finderr program (again, making sure that
$INFORMIXDIR/bin is in your path):
finderr <-num> returns the error text for error -num
finderr <num> returns the error text for error -num
finderr <+num> returns the error text for err num
You can also look up the error number in the Informix Error Messages guide available at Informix's Answers OnLine site (see Informix Documentation).