RedHat Linux Tips

(The page is still under construction.. )

1. How to configure XDCMP for Linux ?
   (XDCMP is a protocol to enable remote desktop connection to a Linux box)
   You can show the desktop of a remote linux machine (running the X Server 
   ) to the client machine running on Windows (using softwares like cygwin)

   The following files are used for XDCMP configuration

   1) xdm-config in /usr/X11R6/lib/X11/xdm
   2) gdm.conf   in /etc/X11/gdm/gdm.conf


In file xdm-config, modify the line to 

! 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


In file gdm.conf modify the line to 
[xdmcp]
# Distributions: Ship with this off.  It is never a safe thing to leave
# out on the net.  Alternatively you can set up /etc/hosts.allow and
# /etc/hosts.deny to only allow say local access.
Enable=true

- restart the machine (or) network service 
- From windows using cygwin shell type
  xwin :0 -query 


2. How to configure SAMBA ? 
   (SAMBA is technique by which the Linux box emulates a Windows NT file server, hence it allows all the files on a Linux machine to be shared using shared folders on a windows network)

Steps:
- vi /etc/smb/smb.conf

And add the following lines

[WebSphere]
	comment = WebSphere
	path = /opt/WebSphere
	writeable = no
	printable = no
        write list = @waslinux      

where the /opt/WebSphere is the directory to be shared
 waslinux - username of the SAMBA user who has write permission to this share.

- useradd 
- passwd  to change the password for newly added user
- Add a user for SAMBA by
   smbpasswd -a 

- restart the SMB daemon by 
   service smb restart
- Logon to a windows machine and type the following line on explorer
  \\\share_name
 Eg. \\xx.xxx.xxx.xxx\WebSphere
 and give the  and the password 

3. How to turn of a service (eg. sendmail) in a particular run-level ?

   Use the chkconfig command .
   For eg. to Disable sendmail service to be turned off by default in 
   run-levels 3 (Multi-user), 5(Multi-user graphical Mode)
   use 
   # chkconfig --level 35 sendmail off

4. How to start a service ?
   service  start
   Eg. to start FTP server on linux, use
   # service vsftpd start

5. How to kill all process by name ?
   Use killall command. For eg. to kill all the java process on the 
   machine use 
   # killall java

6. How to see all the Open ports on Linux ?
   Use 
   # netstat -an 

7. How to issue multiple commands on Bash ?
   # ls && ls /home

8. How to change owner of a file in Linux ?
   chown  filename 

9. How to change group owner of a file in Linux ?
   chgrp  filename

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