SE Linux is a feature of the Linux kernel that provides mandatory access control. This policy based access control system grants far greater control over the resources on a machine than standard Linux access controls such as permissions.
Many modern Linux distributions are shipping with SELinux enabled by default, Fedora 14 and Rhel 6 both install with it enabled.
When you run Recital Web on a SELinux enabled machine and navigate to the default.rsp page you will see something similar to the screen shot below.
If you launch the SELinux troubleshooter you will see the following problem.
SELinux is blocking the apache server from accessing the Recital server running on port 8001.
To manage you SELinux policy you must have the policycoreutils package group installed. The policycoreutils contains the policy core utilities that are required for basic operation of a SELinux system.
If you wish to use a GUI tool, you must install the policycoreutils-gui package.
At the command prompt execute the following:
As root
$ yum install policycoreutils
$ semanage port -a -t http_port_t -p tcp 8001
$ service recital restart
$ service httpd restart
We use the semanage command here to allow the http server access to port 8001. Once you have completed the steps detailed above you can go and navigate back to the default.rsp page in your borwser, where you will find the permission denied message is now replaced by the default.rsp page.
SELinux does a great job of restricting services and daemons so rather than simply disabling it, why not work with it!
When it comes to security, every little bit helps...
To access the menu bar in Recital, press the / key.
Full details on Recital Function Keys can be found in the Key Assist section of the Help menu, or in our documentation wiki here.
Occasionally as a Linux administrator you will be in the situation where working on a remote server and you are left with no option but to force a reboot the system. This may be for a number of reasons, but where I have found it most frequent is when working on Linux clusters in a remote location.
When the "reboot" or "shutdown" commands are executed daemons are gracefully stopped and storage volumes unmounted.
This is usually accomplished via scripts in the /etc/init.d directory which will wait for each daemon to shut down gracefully before proceeding on to the next one. This is where a situation can develop where your Linux server fails to shutdown cleanly leaving you unable to administer the system until it is inspected locally. This is obviously not ideal so the answer is to force a reboot on the system where you can guarantee that the system will power cycle and come back up. The method will not unmount file systems nor sync delayed disk writes, so use this at your own discretion.
To force the kernel to reboot the system we will be making use of the magic SysRq key.
The magic_SysRq_key provides a means to send low level instructions directly to the kernel via the /proc virtual file system.
To enable the use of the magic SysRq option type the following at the command prompt:
echo 1 > /proc/sys/kernel/sysrq
Then to reboot the machine simply enter the following:
echo b > /proc/sysrq-trigger
Voilà! Your system will instantly reboot.
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SET DATADIR TO [ <directory> ]This command is used to specify a directory where database tables, memos, indexes, and dictionary files are located. When a table is being opened this directory is searched first before the current directory and the file search path to locate the table and its associated files. This allows the database tables to be relocated to a different file system without the need to change an existing application.
$ lsof | grep db.exe | grep accounts db.exe 16897 john 6uw REG 253,0 20012 3413872 /usr/recital100/qa/accounts.dbf db.exe 16897 john 7u REG 253,0 4176 3413885 /usr/recital100/qa/accounts.dbxIf you want to check for locks you can use lslk, for example;
$ lslk | grep db.exe | grep accounts db.exe 16897 253,0 3413872 20012 w 0 0 0 12319 0 /usr/recital100/qa/accounts.dbfIf you don't have lslk installed you can install it with one of the updaters, for example on redhat linux:
$ yum update lslk
On entry to the .rsp page.
IF type( _session["state"] ) != "U"m_state = _session["state"]RESTORE DATASESSION FROM m_state
ELSE
// open up your tables for the first timeENDIF
SAVE DATASESSION TO m_state_SESSION["state"] = m_state
This guide will assist you in setting up an rsnapshot backup server on your network. rsnapshot uses rsync via ssh to perform unattended backups of multiple systems in your network. The guide can be found on the centos website here.
If you are using the Oracle Gateway in Recital, make sure the Oracle environment (ORACLE_HOME, ORACLE_SID etc.) is set up before starting the Recital Server. If not, you will see the error ORA-01019. A call to the Oracle environment setup script can be added to the /etc/init.d/recital script if your Recital Server is set to run on startup.