This post brings together a number of past issues which I have not posted previously, discovered while setting up and using iMedia embedded Linux on my diskless LinITX Jupiter test box.
A zip of all the customised scripts and various config files (such as the infamous xorg.conf) are in the repository.
Shell Script Usage
1/ The startup scripts for applications and drivers etc. are in /etc/rcS.d/. You just add scripts to that and they are automatically run. They are all run by /etc/rcS in alpha order. They are grouped by a prefix of M05, M10, M20, M30 etc. – this seems just to be an arbitrary grouping that determines the order for dependencies etc. Note that all of rcS.d/ is run at run level 3 as set in /etc/inittab
The general order of startup is therefore (see /etc/inittab):-
- /etc/rc.init runs, and calls rc.sysinit directly
- /etc/rc.sysinit iterates init.d and runs everything in it. The order is partly determined by an initial grouping number – note the first to run is 00createvar which creates the /var tree on startup (see later)
- /etc/rcS runs as above, iterating /etc/rcS.d/
2/ /usr/local/bin/ has the extra shared shell scripts – rlog, rlog-leafpad, sx (start X), sxr (start X as root), plus start/stop scripts for Tomcat and Glassfish.
In Thunar, you can add file associations for scripts by right clicking in the file and selecting open with other application – for each app you can add a custom launch command below. (I added rlog and rlog-leafpad). If you add an incorrect one (I added beaver by mistake) Thunar may not let you remove it from the list. Just edit ~/.local/share/applications/defaults.list and remove it from there. Note that /usr/local/bin/ is already on the path so all the script in it are visible – good place to put other global scripts.
Note that you can add scripts to e.g. a program launcher on the top panel bar – right click and create a program launcher, then add items to it – useful for scripts which run without parameters (unlike the rlog and rlog-leafpad above which act on files and therefore are Thunar’s context menu for the files they operate on). When adding a script as an item to a program launcher, the ‘startup notification’ just gives a wait cursor while the script is running (useful). Running in an explicit terminal window is WEIRD – for example for glassfish I set the middle icon on the RHS pane to “terminal”, and set the command to be “aterm -e start-glassfish”. I did not tick “Run in Terminal” as this did not work however!
Logging under iMedia Linux
1/ Logs are stored under the /var tree which is recreated at startup each time see above, so log files are purged as we are running on a small flash based distro. Therefore, Tomcat and Glassfish for example are set to use sym links to link their log directories from their normal install directories to be under /var/log/. There is some trickery to this – for Glassfish I make sure that the *normal* log folder is not present (renaming it with a date/time stamp if required) else the sym link is set up wrongly.
2/ Some logs (but by no means all) in /var/logs/ are circular buffers handled by emlog – see here for details. They show in Thunar as ‘character type devices’ and need copying to be visible – /usr/local/bin/rlog does this using nbcat as per the emlog site. I also added /usr/local/bin/rlog-leafpad which does the copy and fires up leafpad on the result. Note that as the emlog site states, you cannot list such a log when active using cat as a non blocking read is required – hence the need for nbcat as used by rlog and rlog-leafpad.
Installing new Applications
1/ Installing new apps is a pain, as rpm installs don’t appear to be supported etc. I tried installing various zipped tarballs of VNC/RDP alternatives for remote desktop but they all needed dependant libraries I did not have, so I had to give up. I think you can build from source to add things but did not go that far! The apps I did install successfully – java 1.6.0_29, tomcat 6.0.29 and Glassfish 3.0.1 – was all installed in folders under /opt as this appeared to be the correct place. Note that for Tomcat, I placed the config files under /etc/apache-tomcat-6.0.20/conf/ and sym-linked them from the ‘expected’ place, /opt/apache-tomcat-6.0.20/opt/, as this appeared to be correct protocol – other apps placed their config under /etc/ and linked to it from their install directory under /opt/. However I did not go to the trouble of doing this for Glassfish – it would be possible (I did do it for the log directory) but the directory structure is more complex.
2/ I did have success with Java – I just ran the .bin install kit of the latest Linux version of the sun Java SE (jdk6u29), and it all unzipped properly and ran fine. Thankfully there were no library problems – probably because there had already been an earlier working jdk6 already installed by default. I added a shell script /etc/profile.d/java-jdk1.6.0_29.sh which created the JAVA_HOME and added the bin directory to the path, but note that this did not work for init time shell scripts for either Tomcat or Glassfish, so their startup scripts had to add their own definitions to work.
3/ I successfully installed Glassfish 3.0.1 (from the zip kit download). To get it to work I had to upgrade Java as above as I got errors otherwise, and the old jdk was below the minimum certified version. However, it worked fine after upgrading java. Note that to stop it checking for updates on startup I just renamed /opt/glassfish-3.0.1-web/glassfish/modules/console-updatecenter-plugin.jar by adding “.disabled” on the end. You can achieve the same thing using the updatetool, but this failed to install properly due to a python error/dependency. I also removed the default jsf-api.jar and jsf-impl.jar from the same folder as above, and added the Mojarra 2.0.4 FCS jars to the folder instead, as my apps needed this version. Note that this also speeds up the startup of the Glassfish admin tool. See my notes here about clearing the osgi cache if you do this.
4/ For Tomcat and Glassfish I separated out the log directory creation from the actual startup, using separate scripts. The log creation is always run, and so sits under /etc/rcS.d/, and the auto startup is optional and may sit under /etc/rcS.disabled/ as a placeholder if it is not autostarted. However, as the log directories under /var/ are always setup, you can then manually start them if desired and they will still work. This is done with the scripts in /usr/local/bin/ – start-glassfish/stop-glassfish/start-tomcat/stop-tomcat. As this directory is on the path, the scripts can be directly run from a terminal window OR from a remote SSH window BUT you would need to be logged in as root to do it.
Graphical Remote Desktop
Re remote desktop, it is in theory possible to use a windows based X server and connect in that way. To do this, you need to run an X display manager on the Linux box to handle the xdmcp protocol etc. imedia linux does have /usr/bin/xdm which is an old display manager. I did manage to run it from the initial login prompt before typing startx, just by typing xdm, and it popped a login screen. However it would not connect to xfce. It recognised a valid login and tried to do something, failed, and redisplayed itself. An invalid login gave a login failure. I also managed to run the launcher from XMING under windows, and got as far as connecting to xdm. to do this I edited /etc/X11/xdm/Xaccess to enable the “*” entry to allow all comers. I also experimented with editing /etc/X11/xdm/xdm-config and set DisplayManager*authorize to false, and tried commenting out the last line as follows :-
! SECURITY: do not listen for XDMCP or Chooser requests
! Comment out this line if you want to manage X terminals with xdm
!DisplayManager.requestPort: 0
I managed to get XMING to display the same xdm login screen that I got locally, which was a good start – I knew I had a connection working. However, I realised in the end that xfce does not appear to be using a display manager – it simplifies things and bypasses it, and to set up xdm to link properly to xfce and to work remotely looked like loads of setting up with no instructions on how to do it properly.
I therefore sadly gave up on this and admitted defeat on installing any kind of graphical remote desktop!
Samba
I got the samba server to share folders successfully – I added the shares in /etc/samba/smb.conf. Security was set to user (security = user). I tried setting “valid users=” to a list of users, to allow restriction of users e.g. to glassfish/tomcat log folders, but could not get this to work, so I left it out.
Note that I did need to use “smbpasswd -a username” to add an existing linux user to the samba user list, and give it a password. You need to run as root to do this, or it merely allows you to change your own password. smbusers allows you to map external users (used by windows clients) to linux users – see here. Note that you don’t need to do this – you can just use the linux names. Note also that when adding/setting passwords with smbpasswd, you *always* use the Linux name, not the samba alias. Some other useful links for Samba follow:-
Ftp, Telnet and SSH
1/ ftp is enabled by default via vsftp. The config file is in /etc/vsftpd/vsftpd.conf. The default settings are pretty sensible in opening it up for use in a secur local lan. ftp works via all the local linux accounts including root. The log is in /vat/log/vsftpd.log.
2/ Telnet works but does not allow root access (presumably as too insecure). utelnetd is the daemon but there is no documentation for it on the net I could find. SSH works fine via the sshd and allows root access, but could not find any config files or logging for it, although it is documented on the net – the man pages are here, however the config files mentioned for the daemon do not appear to be present under imedia Linux. No problem, it is set up fine for LAN use and works well from putty in ssh mode.
