Manage services on ubuntu

To add/remove service in ubuntu. Manually you can put init script in /etc/init.d then create symbolic link from /etc/rc?.d/S[NN]name or K[NN]name to /etc/init.d/scriptname.[S for start and K for stop]
In ubuntu has a tool to manage init scripts call update-rc.d. For example if you want to start serviceA in runlevel 2 3 4 5 with sequence number 18 and stop in runlevel 0 1 6 with sequence number 99 use the command.[the scriptA must already create in /etc/init.d]

pnix@pnix-a7n:~$ sudo update-rc.d serviceA start 18 2 3 4 5 . stop 99 0 1 6

In redhat base linux, i use chkconfig do the same thing. For more detail try 'man chkconfig'.

Comments

Fixing sendmail take a long time to start

I notice that my database box[FC6+Oracle10.2] take along time to startup. Sendmail and sm-client very very slow to start[ about 5 minutes ]. There's something wrong in /etc/hosts file. 'newalises' command take long time to update and finish with error below. [root@ora10g ~]# newaliases WARNING: local host name (ora10g) is not qualified; see cf/README: WHO AM I? /etc/aliases: 76 aliases, longest 10 bytes, 765 bytes total [root@ora10g ~]# cat /etc/hosts # Do not remove the following line, or various programs # that require network functionality will fail. 127.0.0.1 localhost.localdomain localhost 192.168.1.55 ora10g [root@ora10g ~]# To fix this, custom hostname[ora10g] need to append to localhost line in /etc/hosts. [root@ora10g ~]# cat /etc/hosts # Do not remove the following line, or various programs # that require network functionality will fail. 127.0.0.1 localhost.localdomain localhost ora10g 192.168.1.55 ora10g [root@ora10g ~]# newaliases /etc/alia

Too many open files

Last week tomcat log file report many error about "Too many open files" when it has high traffic. Some in catalina_log say 2007-04-07 16:13:40 HttpProcessor[80][272] Starting background thread 2007-04-07 16:13:40 HttpConnector[80] accept: java.net.SocketException: Too many open files and here is from localhost_log 2007-04-07 16:13:40 StandardWrapperValve[myservlet]: Servlet.service() for servlet myservlet threw exception java.io.FileNotFoundException: /home/log/mylog_070407.log (Too many open files) This is because too many file descriptors're opened by tomcat. File descriptor can be limited in both system level and shell level. To check maximum number of fd in system type 'cat /proc/sys/fs/file-max'. In my case it is 65536(someone said it should set to 200000). Tomcat error when try to open socket number 272 so I think 65536 is ok for me for now. Anyway if u want to set it add 'fs.file-max = 200000' to /etc/sysctl.conf pnix@pnix-a7:~$ cat /proc/sys/fs/fil

using Class.getResource() load resource file in Eclipse

There are many ways to load resource file in java app. What sun recommended is using Class.getResource(" resource_name ") or Class.getResourceAsStream(" resource_name ") then you will get URL and InputStream respectively. If resource_name is specified without "/", it will be prepend with Class package. So resource file must be in same place[folder structure] as the Class. What I love to do is call getResource() with "/" and put resource file at the root of package. This way i can have separate resource folder. below is in Eclipse, 1. From Package explorer right click src folder->click import 2. In import dialog, Choose General->File System ->next 3. from directory:->Browse to your resource folder. 4. to folder:-> I add "resource" as a folder name under src folder. then click "Finish". In the code, load resource with this.getClass().getResource("/resource/buttons1.png") or this.getClass().getResourceAs

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