The system services can be classified into 2 types: /etc/xinetd.d based & /etc/rc.d/init.d based services.
/etc/xinetd.d --based services are
telnet finger imap ipop2 ipop3
pop3s rlogin rsh sgi_fam
the executable daemons of these services are at /etc/rc.d/init.d, named xinetd
/etc/rc.d/init.d – based services are
apmd autofs dhcpd halt httpd
iptables kudzu named network nfs
portmap sendmail snmpd smb ssh
squid vncserver vsftpd xinetd ypbind
apmd automatic power management daemon
autofs automatic file system
dhcpd dynamic host configuring protocol daemon
httpd hyper text transfer protocol daemon
iptables for fire wall security
kudzu enabling plug and play facility
named for bind (DNS-Domain Name System) server
nfs network file system
portmap services that starts when n/w is enabled
sendmail used for mail server application
snmpd simple n/w management protocol
smb samba server (Linux/windows connectivity)
ssh secure shell daemon
squid proxy server
vncserver remote desktop sharing
vsftpd very secure file transfer protocol daemon
xinetd enable /etc/xinetd.d services
ypbind NIS(n/w info server) client
ypserv NIS server
zebra used for routing.
Ways of enabling these services:-
chkconfig enabling a service this way keeps a service enabled until next restart.
#chkconfig - -list service_name displays the current run level of that service.
#chkconfig service_name on/off used to enable/disable a particular service
#chkconfig - -levels 35 service_name on enables that service on run levels 3,5
Run control script resides in /etc/rc.d contains script files for rc0 to rc6. [the script file starting with ‘S’ represents the scripts to be start-up during next system boot and the script starting with K represents the stopped scripts].
#ntsysv cmnd used to enable or disable a service during next start up too.
#service service-name start/stop/restart/reload/status
Configuring a YUM Repository
Make sure ftp server package is selected while installing the m/c in which we are planning to create a yum repository.
Copy all rpms from the corresponding directory on RHEL DVD to somewhere under /var/ftp/ say /var/ftp/pub/Server
install createrepo rpm which is inside the rhel dvd
that's all yum repository is ready to use.
To make it available for other machines in the network via ftp
#chkconfig vsftpd on
On client machines
let our yum repository is available at 192.168.0.254
#cat > test.repo
name= my first repo
#yum list all
To check whether a package is installed or not
#rpm -qa | grep -i
To install something using YUM
/etc more tremcap
Etc less termcap
Find -perm 700
Find - uid 500
Umask –S | umask in symbolic form
Find –print | grep xorg.conf
Environmental Variables $PATH $DISPLAY $PS1 $TERM $USER $HOME $SHELL
Set command shows all the variables